DEFF Research Database (Denmark)
Madsen, Henrik; Zhou, Jianjun; Hansen, Lars Henrik
1997-01-01
This paper describes a case study of identifying the physical model (or the grey box model) of a hydraulic test robot. The obtained model is intended to provide a basis for model-based control of the robot. The physical model is formulated in continuous time and is derived by application...
DEFF Research Database (Denmark)
Madsen, Henrik; Zhou, Jianjun; Hansen, Lars Henrik
1997-01-01
This paper describes a case study of identifying the physical model (or the grey box model) of a hydraulic test robot. The obtained model is intended to provide a basis for model-based control of the robot. The physical model is formulated in continuous time and is derived by application...... of the laws of physics on the system. The unknown (or uncertain) parameters are estimated with Maximum Likelihood (ML) parameter estimation. The identified model has been evaluated by comparing the measurements with simulation of the model. The identified model was much more capable of describing the dynamics...... of the system than the deterministic model....
Hydraulic Arm Modeling via Matlab SimHydraulics
Věchet, Stanislav; Krejsa, Jiří
2009-01-01
System modeling is a vital tool for cost reduction and design process speed up in most engineering fields. The paper is focused on modeling of hydraulic arm as a part of intelligent prosthesis project, in the form of 2DOF open kinematic chain. The arm model combines mechanical, hydraulic and electric subsystems and uses Matlab as modeling tool. SimMechanics Matlab extension is used for mechanical part modeling, SimHydraulics toolbox is used for modeling of hydraulic circuit used for actuating...
Hydraulic Redistribution: A Modeling Perspective
Daly, E.; Verma, P.; Loheide, S. P., III
2014-12-01
Roots play a key role in the soil water balance. They extract and transport water for transpiration, which usually represents the most important soil water loss in vegetated areas, and can redistribute soil water, thereby increasing transpiration rates and enhancing root nutrient uptake. We present here a two-dimensional model capable of describing two key aspects of root water uptake: root water compensation and hydraulic redistribution. Root water compensation is the ability of root systems to respond to the reduction of water uptake from areas of the soil with low soil water potential by increasing the water uptake from the roots in soil parts with higher water potential. Hydraulic redistribution is a passive transfer of water through the root system from areas of the soil with greater water potential to areas with lower water potential. Both mechanisms are driven by gradients of water potential in the soil and the roots. The inclusion of root water compensation and hydraulic redistribution in models can be achieved by describing root water uptake as a function of the difference in water potential between soil and root xylem. We use a model comprising the Richards equation for the water flow in variably saturated soils and the Darcy's equation for the water flow in the xylem. The two equations are coupled via a sink term, which is assumed to be proportional to the difference between soil and xylem water potentials. The model is applied in two case studies to describe vertical and horizontal hydraulic redistribution and the interaction between vegetation with different root depths. In the case of horizontal redistribution, the model is used to reproduce the fluxes of water across the root system of a tree subjected to uneven irrigation. This example can be extended to situations when only part of the root system has access to water, such as vegetation near creeks, trees at the edge of forests, and street trees in urban areas. The second case is inspired by recent
Helical coil thermal hydraulic model
Caramello, M.; Bertani, C.; De Salve, M.; Panella, B.
2014-11-01
A model has been developed in Matlab environment for the thermal hydraulic analysis of helical coil and shell steam generators. The model considers the internal flow inside one helix and its associated control volume of water on the external side, both characterized by their inlet thermodynamic conditions and the characteristic geometry data. The model evaluates the behaviour of the thermal-hydraulic parameters of the two fluids, such as temperature, pressure, heat transfer coefficients, flow quality, void fraction and heat flux. The evaluation of the heat transfer coefficients as well as the pressure drops has been performed by means of the most validated literature correlations. The model has been applied to one of the steam generators of the IRIS modular reactor and a comparison has been performed with the RELAP5/Mod.3.3 code applied to an inclined straight pipe that has the same length and the same elevation change between inlet and outlet of the real helix. The predictions of the developed model and RELAP5/Mod.3.3 code are in fairly good agreement before the dryout region, while the dryout front inside the helical pipes is predicted at a lower distance from inlet by the model.
Modeling and Simulation of Hydraulic Engine Mounts
Institute of Scientific and Technical Information of China (English)
DUAN Shanzhong; Marshall McNea
2012-01-01
Hydraulic engine mounts are widely used in automotive powertrains for vibration isolation.A lumped mechanical parameter model is a traditional approach to model and simulate such mounts.This paper presents a dynamical model of a passive hydraulic engine mount with a double-chamber,an inertia track,a decoupler,and a plunger.The model is developed based on analogy between electrical systems and mechanical-hydraulic systems.The model is established to capture both low and high frequency dynatmic behaviors of the hydraulic mount.The model will be further used to find the approximate pulse responses of the mounts in terms of the force transmission and top chamber pressure.The close form solution from the simplifiod linear model may provide some insight into the highly nonlinear behavior of the mounts.Based on the model,computer simulation has been carried out to study dynamic performance of the hydraulic mount.
SITMILARITY LAW FOR HYDRAULIC DISTORTED MODEL
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Newton's general similarity criterion was applied to the distorted model. The results for the similarities of gravity force, drag force and pressure force are identical with those derived from relevant differential equations of fluid flow. And the selected limits of the distorted ratio were studied and the simulation of roughness coefficient of distorted model was conducted by means of hydraulic test.
Measurement and modeling of unsaturated hydraulic conductivity
Perkins, Kim S.; Elango, Lakshmanan
2011-01-01
The unsaturated zone plays an extremely important hydrologic role that influences water quality and quantity, ecosystem function and health, the connection between atmospheric and terrestrial processes, nutrient cycling, soil development, and natural hazards such as flooding and landslides. Unsaturated hydraulic conductivity is one of the main properties considered to govern flow; however it is very difficult to measure accurately. Knowledge of the highly nonlinear relationship between unsaturated hydraulic conductivity (K) and volumetric water content is required for widely-used models of water flow and solute transport processes in the unsaturated zone. Measurement of unsaturated hydraulic conductivity of sediments is costly and time consuming, therefore use of models that estimate this property from more easily measured bulk-physical properties is common. In hydrologic studies, calculations based on property-transfer models informed by hydraulic property databases are often used in lieu of measured data from the site of interest. Reliance on database-informed predicted values with the use of neural networks has become increasingly common. Hydraulic properties predicted using databases may be adequate in some applications, but not others. This chapter will discuss, by way of examples, various techniques used to measure and model hydraulic conductivity as a function of water content, K. The parameters that describe the K curve obtained by different methods are used directly in Richards’ equation-based numerical models, which have some degree of sensitivity to those parameters. This chapter will explore the complications of using laboratory measured or estimated properties for field scale investigations to shed light on how adequately the processes are represented. Additionally, some more recent concepts for representing unsaturated-zone flow processes will be discussed.
Partially decoupled modeling of hydraulic fracturing processes
Energy Technology Data Exchange (ETDEWEB)
Settari, A.; Puchyr, P.J.; Bachman, R.C. (Simtech Consulting Services, Calgary (CA))
1990-02-01
A new method of partial decoupling of the problem of modeling a hydraulic fracture in a reservoir is described. According to the authors this approach has significant advantages over previous methods with fully coupled or completely uncoupled models. Better accuracy can be achieved in modeling the fracture propagation, and the new system is very efficient and versatile. Virtually any reservoir model can be used for predicting postfracture productivity. Examples of single- and multiphase applications for modeling fractured wells are discussed.
Decker, Robert L.; Kirby, Klane
This curriculum guide contains a course in hydraulics to train entry-level workers for automotive mechanics and other fields that utilize hydraulics. The module contains 14 instructional units that cover the following topics: (1) introduction to hydraulics; (2) fundamentals of hydraulics; (3) reservoirs; (4) lines, fittings, and couplers; (5)…
Universal asymptotic umbrella for hydraulic fracture modeling
Linkov, Aleksandr M
2014-01-01
The paper presents universal asymptotic solution needed for efficient modeling of hydraulic fractures. We show that when neglecting the lag, there is universal asymptotic equation for the near-front opening. It appears that apart from the mechanical properties of fluid and rock, the asymptotic opening depends merely on the local speed of fracture propagation. This implies that, on one hand, the global problem is ill-posed, when trying to solve it as a boundary value problem under a fixed position of the front. On the other hand, when properly used, the universal asymptotics drastically facilitates solving hydraulic fracture problems (both analytically and numerically). We derive simple universal asymptotics and comment on their employment for efficient numerical simulation of hydraulic fractures, in particular, by well-established Level Set and Fast Marching Methods.
Model for polygonal hydraulic jumps
DEFF Research Database (Denmark)
Martens, Erik Andreas; Watanabe, Shinya; Bohr, Tomas
2012-01-01
) near the free surface in the jump region. The model consists of mass conservation and radial force balance between hydrostatic pressure and viscous stresses on the roller surface. In addition, we consider the azimuthal force balance, primarily between pressure and viscosity, but also including...
Hydraulic Modeling of Lock Approaches
2016-08-01
cation was that the guidewall design changed from a solid wall to one on pilings in which water was allowed to flow through and/or under the wall ...develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the...magnitudes and directions at lock approaches for open river conditions. The meshes were developed using the Surface- water Modeling System. The two
A Computational Model of Hydraulic Volume Displacement Drive
Directory of Open Access Journals (Sweden)
V. N. Pil'gunov
2014-01-01
Full Text Available The paper offers a computational model of industrial-purpose hydraulic drive with two hydraulic volume adjustable working chamber machines (pump and motor. Adjustable pump equipped with the pressure control unit can be run together with several adjustable hydraulic motors on the principle of three-phase hydraulic socket-outlet with high-pressure lines, drain, and drainage system. The paper considers the pressure-controlled hydrostatic transmission with hydraulic motor as an output link. It shows a possibility to create a saving hydraulic drive using a functional tie between the adjusting parameters of the pump and hydraulic motor through the pressure difference, torque, and angular rate of the hydraulic motor shaft rotation. The programmable logic controller can implement such tie. The Coulomb and viscous frictions are taken into consideration when developing a computational model of the hydraulic volume displacement drive. Discharge balance considers external and internal leakages in equivalent clearances of hydraulic machines, as well as compression loss volume caused by hydraulic fluid compressibility and deformation of pipe walls. To correct dynamic properties of hydraulic drive, the paper offers that in discharge balance are included the additional regulated external leakages in the open circuit of hydraulic drive and regulated internal leakages in the closed-loop circuit. Generalized differential equations having functional multipliers and multilinked nature have been obtained to describe the operation of hydraulic positioning and speed drive with two hydraulic volume adjustable working chamber machines. It is shown that a proposed computational model of hydraulic drive can be taken into consideration in development of LS («Load-Sensing» drives, in which the pumping pressure is tuned to the value required for the most loaded slave motor to overcome the load. Results attained can be used both in designing the industrial-purpose heavy
Institute of Scientific and Technical Information of China (English)
张成涛; 谭彧; 吴刚; 王书茂
2013-01-01
In recent years, combine harvester navigation system based on machine vision had important significance in improving the harvesting efficiency of combine harvester, reducing the labor intensity of the driver and so on. In order to realize the automatic steering control of the combine operation path, it is necessary to reconstruct the original hydraulic steering system of combine harvester. To analyze the steering performance of the modified electronically controlled hydraulic steering system for combine harvester in visual navigation system, mathematical models of the electronically controlled hydraulic steering system were established after introducing the structure of combine harvester visual navigation system. The system was mainly composed of combine harvester body, full hydraulic steering, steering transmission mechanism and hybrid stepping motor. In this paper, the mathematical models of the parts were established respectively. The steering model of combine harvester was firstly simplified to linear 2-DOF rear wheel steering vehicle model, and the basic handling dynamics model of combine harvester was established. Then, the dynamic mathematical model of simplified hydraulic steering system was given in the analysis of the fully hydraulic steering work principle for combine harvester. And then, the static model of the steering transmission mechanism was established according to its geometrical structures. Finally, the stepping motor model was simplified as an inertial system according to the step response performance, and its transfer function was given. The electronically controlled hydraulic steering system was simulated through the joint simulation method of each mathematical model by Simulink software. In order to verify the correctness of simulation models, the dynamic response characteristics of steering system was tested with the steering wheel angle step input of 90° on Xinjiang 2A combine harvester. In the real vehicle test, vehicle yaw rate was
Hydraulic fracture model comparison study: Complete results
Energy Technology Data Exchange (ETDEWEB)
Warpinski, N.R. [Sandia National Labs., Albuquerque, NM (United States); Abou-Sayed, I.S. [Mobil Exploration and Production Services (United States); Moschovidis, Z. [Amoco Production Co. (US); Parker, C. [CONOCO (US)
1993-02-01
Large quantities of natural gas exist in low permeability reservoirs throughout the US. Characteristics of these reservoirs, however, make production difficult and often economic and stimulation is required. Because of the diversity of application, hydraulic fracture design models must be able to account for widely varying rock properties, reservoir properties, in situ stresses, fracturing fluids, and proppant loads. As a result, fracture simulation has emerged as a highly complex endeavor that must be able to describe many different physical processes. The objective of this study was to develop a comparative study of hydraulic-fracture simulators in order to provide stimulation engineers with the necessary information to make rational decisions on the type of models most suited for their needs. This report compares the fracture modeling results of twelve different simulators, some of them run in different modes for eight separate design cases. Comparisons of length, width, height, net pressure, maximum width at the wellbore, average width at the wellbore, and average width in the fracture have been made, both for the final geometry and as a function of time. For the models in this study, differences in fracture length, height and width are often greater than a factor of two. In addition, several comparisons of the same model with different options show a large variability in model output depending upon the options chosen. Two comparisons were made of the same model run by different companies; in both cases the agreement was good. 41 refs., 54 figs., 83 tabs.
Thermal-hydraulic modeling and analysis of hydraulic system by pseudo-bond graph
Institute of Scientific and Technical Information of China (English)
胡均平; 李科军
2015-01-01
To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.
Soil hydraulic properties near saturation, an improved conductivity model
DEFF Research Database (Denmark)
Børgesen, Christen Duus; Jacobsen, Ole Hørbye; Hansen, Søren;
2006-01-01
The hydraulic properties near saturation can change dramatically due to the presence of macropores that are usually difficult to handle in traditional pore size models. The purpose of this study is to establish a data set on hydraulic conductivity near saturation, test the predictive capability...... of commonly used hydraulic conductivity models and give suggestions for improved models. Water retention and near saturated and saturated hydraulic conductivity were measured for a variety of 81 top and subsoils. The hydraulic conductivity models by van Genuchten [van Genuchten, 1980. A closed-form equation...... for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. 44, 892–898.] (vGM) and Brooks and Corey, modified by Jarvis [Jarvis, 1991. MACRO—A Model of Water Movement and Solute Transport in Macroporous Soils. Swedish University of Agricultural Sciences. Department of Soil Sciences...
Hydrological and hydraulic modelling of the Nyl River floodplain Part ...
African Journals Online (AJOL)
2007-01-01
Jan 1, 2007 ... Keywords: Nyl River floodplain, Nylsvlei, Nylsvley Nature Reserve, modelling wetland hydraulics, wetland evapotranspiration ..... A review of suitable methods for estimating evapotranspira- ..... ingum routing. J. Hydrol.
Representing plant hydraulics in a global Earth system model.
Kennedy, D.; Gentine, P.
2015-12-01
Earth system models need improvement to reproduce observed seasonal and diurnal cycles of photosynthesis and respiration. Model water stress parameterizations lag behind the plant physiology literature. A plant hydraulics model is developed and deployed in a global Earth system model (NCAR CESM 1.2.2 with CLM 4.5). Assimilation and transpiration are attenuated according to literature cavitation curves. Water stress is evaluated based on plant functional type hydraulic parameters forced by soil moisture and atmospheric conditions. Resolving the plant water status allows for modelling divergent strategies for water stress. The case of isohydric versus anisohydric species is presented, showing that including plant hydraulic traits alter modelled photosynthesis and transpiration.
Hydraulic modelling of drinking water treatment plant operations
L. C. Rietveld; Borger, K.J.; Van Schagen, K.M.; Mesman, G.A.M.; G. I. M. Worm
2008-01-01
For a drinking water treatment plant simulation, water quality models, a hydraulic model, a process-control model, an object model, data management, training and decision-support features and a graphic user interface have been integrated. The integration of a hydraulic model in the simulator is necessary to correctly determine the division of flows over the plant's lanes and, thus, the flow through the individual treatment units, based on valve positions and pump speeds. The flow through a un...
THE THEORETICAL MODEL FOR PREDICTING CIRCULATION VELOCITY OF HYDRAULIC BRAKE
Institute of Scientific and Technical Information of China (English)
刘英林; 侯春生
1997-01-01
By rational hypothesis of fluid flow pattern, applied the law of conservation of energy and integrated the laboratory test results, finished the prediction by the theoretical model of circulation velocity of hydraulic brake which is important parameter. Thus provide the theoritical basis for hydraulic brake of belt conveyor whose research has just been started.
COHESIVE ZONE FINITE ELEMENT-BASED MODELING OF HYDRAULIC FRACTURES
Institute of Scientific and Technical Information of China (English)
Zuorong Chen; A.P. Bunger; Xi Zhang; Robert G. Jeffrey
2009-01-01
Hydraulic fracturing is a powerful technology used to stimulate fluid production from reservoirs. The fully 3-D numerical simulation of the hydraulic fracturing process is of great importance to the efficient application of this technology, but is also a great challenge because of the strong nonlinear coupling between the viscous flow of fluid and fracture propagation. By taking advantage of a cohesive zone method to simulate the fracture process, a finite element model based on the existing pore pressure cohesive finite elements has been established to investigate the propagation of a penny-shaped hydraulic fracture in an infinite elastic medium. The effect of cohesive material parameters and fluid viscosity on the hydraulic fracture behaviour has been investigated. Excellent agreement between the finite element results and analytical solutions for the limiting case where the fracture process is dominated by rock fracture toughness demonstrates the ability of the cohesive zone finite element model in simulating the hydraulic fracture growth for this case.
Modeling and parameter estimation for hydraulic system of excavator's arm
Institute of Scientific and Technical Information of China (English)
HE Qing-hua; HAO Peng; ZHANG Da-qing
2008-01-01
A retrofitted electro-bydraulic proportional system for hydraulic excavator was introduced firstly. According to the principle and characteristic of load independent flow distribution(LUDV)system, taking boom hydraulic system as an example and ignoring the leakage of hydraulic cylinder and the mass of oil in it,a force equilibrium equation and a continuous equation of hydraulic cylinder were set up.Based On the flow equation of electro-hydraulic proportional valve, the pressure passing through the valve and the difference of pressure were tested and analyzed.The results show that the difference of pressure does not change with load, and it approximates to 2.0 MPa. And then, assume the flow across the valve is directly proportional to spool displacement andis not influenced by load, a simplified model of electro-hydraulic system was put forward. At the same time, by analyzing the structure and load-bearing of boom instrument, and combining moment equivalent equation of manipulator with rotating law, the estimation methods and equations for such parameters as equivalent mass and bearing force of hydraulic cylinder were set up. Finally, the step response of flow of boom cylinder was tested when the electro-hydraulic proportional valve was controlled by the stepcurrent. Based on the experiment curve, the flow gain coefficient of valve is identified as 2.825×10-4m3/(s·A)and the model is verified.
Hydraulic modelling of drinking water treatment plant operations
Directory of Open Access Journals (Sweden)
K. J. Borger
2008-10-01
Full Text Available For a drinking water treatment plant simulation, water quality models, a hydraulic model, a process-control model, an object model, data management, training and decision-support features and a graphic user interface have been integrated. The integration of a hydraulic model in the simulator is necessary to correctly determine the division of flows over the plant's lanes and, thus, the flow through the individual treatment units, based on valve positions and pump speeds. The flow through a unit is one of the most important parameters in terms of a unit's effectiveness. In the present paper, a new EPAnet library is presented with the typical hydraulic elements for drinking water treatment processes. Using this library, a hydraulic model was set up and validated for the drinking water treatment plant Harderbroek.
Directory of Open Access Journals (Sweden)
Paola Patiño
2012-04-01
Full Text Available Hydrodynamic phenomena take place within water treatment plants associated with physical, operational and environmental factors which can affect the water quality. This study evaluated a hydraulic clarifier’s hydrodynamic pattern using sludge recirculation through continuous tracer test leading to determining hydraulic behaviour indicators and simplified flow models. The clarifier had dual flow with a predominantly complete mixture during the hours in which higher temperatures were reported for affluent water compared to those reported inside the reactor, causing the formation of density currents promoting mixing in the reactor and increased turbidity in the effluent. The hydraulic indicators and the Wolf-Resnick model had higher sensitivity to the influence of temperature on reactor hydrodynamics.
A Simple Hydraulic Analog Model of Oxidative Phosphorylation.
Willis, Wayne T; Jackman, Matthew R; Messer, Jeffrey I; Kuzmiak-Glancy, Sarah; Glancy, Brian
2016-06-01
Mitochondrial oxidative phosphorylation is the primary source of cellular energy transduction in mammals. This energy conversion involves dozens of enzymatic reactions, energetic intermediates, and the dynamic interactions among them. With the goal of providing greater insight into the complex thermodynamics and kinetics ("thermokinetics") of mitochondrial energy transduction, a simple hydraulic analog model of oxidative phosphorylation is presented. In the hydraulic model, water tanks represent the forward and back "pressures" exerted by thermodynamic driving forces: the matrix redox potential (ΔGredox), the electrochemical potential for protons across the mitochondrial inner membrane (ΔGH), and the free energy of adenosine 5'-triphosphate (ATP) (ΔGATP). Net water flow proceeds from tanks with higher water pressure to tanks with lower pressure through "enzyme pipes" whose diameters represent the conductances (effective activities) of the proteins that catalyze the energy transfer. These enzyme pipes include the reactions of dehydrogenase enzymes, the electron transport chain (ETC), and the combined action of ATP synthase plus the ATP-adenosine 5'-diphosphate exchanger that spans the inner membrane. In addition, reactive oxygen species production is included in the model as a leak that is driven out of the ETC pipe by high pressure (high ΔGredox) and a proton leak dependent on the ΔGH for both its driving force and the conductance of the leak pathway. Model water pressures and flows are shown to simulate thermodynamic forces and metabolic fluxes that have been experimentally observed in mammalian skeletal muscle in response to acute exercise, chronic endurance training, and reduced substrate availability, as well as account for the thermokinetic behavior of mitochondria from fast- and slow-twitch skeletal muscle and the metabolic capacitance of the creatine kinase reaction.
Modelling the Hydraulic Processes on Constructed Stormwater Wetland
Directory of Open Access Journals (Sweden)
Isri Ronald Mangangka
2017-03-01
Full Text Available Constructed stormwater wetlands are manmade, shallow, and extensively vegetated water bodies which promote runoff volume and peak flow reduction, and also treat stormwater runoff quality. Researchers have noted that treatment processes of runoff in a constructed wetland are influenced by a range of hydraulic factors, which can vary during a rainfall event, and their influence on treatment can also vary as the event progresses. Variation in hydraulic factors during an event can only be generated using a detailed modelling approach, which was adopted in this research by developing a hydraulic conceptual model. The developed model was calibrated using trial and error procedures by comparing the model outflow with the measured field outflow data. The accuracy of the developed model was analyzed using a well-known statistical analysis method developed based on the regression analysis technique. The analysis results show that the developed model is satisfactory.
Reliability modeling of hydraulic system of drum shearer machine
Institute of Scientific and Technical Information of China (English)
SEYED HADI Hoseinie; MOHAMMAD Ataie; REZA Khalookakaei; UDAY Kumar
2011-01-01
The hydraulic system plays an important role in supplying power and its transition to other working parts of a coal shearer machine.In this paper,the reliability of the hydraulic system of a drum shearer was analyzed.A case study was done in the Tabas Coal Mine in Iran for failure data collection.The results of the statistical analysis show that the time between failures (TBF)data of this system followed the 3-parameters Weibull distribution.There is about a 54％ chance that the hydraulic system of the drum shearer will not fail for the first 50 h of operation.The developed model shows that the reliability of the hydraulic system reduces to a zero value after approximately 1 650 hours of operation.The failure rate of this system decreases when time increases.Therefore,corrective maintenance(run-to-failure)was selected as the best maintenance strategy for it.
An XFEM Model for Hydraulic Fracturing in Partially Saturated Rocks
Directory of Open Access Journals (Sweden)
Salimzadeh Saeed
2016-01-01
Full Text Available Hydraulic fracturing is a complex multi-physics phenomenon. Numerous analytical and numerical models of hydraulic fracturing processes have been proposed. Analytical solutions commonly are able to model the growth of a single hydraulic fracture into an initially intact, homogeneous rock mass. Numerical models are able to analyse complex problems such as multiple hydraulic fractures and fracturing in heterogeneous media. However, majority of available models are restricted to single-phase flow through fracture and permeable porous rock. This is not compatible with actual field conditions where the injected fluid does not have similar properties as the host fluid. In this study we present a fully coupled hydro-poroelastic model which incorporates two fluids i.e. fracturing fluid and host fluid. Flow through fracture is defined based on lubrication assumption, while flow through matrix is defined as Darcy flow. The fracture discontinuity in the mechanical model is captured using eXtended Finite Element Method (XFEM while the fracture propagation criterion is defined through cohesive fracture model. The discontinuous matrix fluid velocity across fracture is modelled using leak-off loading which couples fracture flow and matrix flow. The proposed model has been discretised using standard Galerkin method, implemented in Matlab and verified against several published solutions. Multiple hydraulic fracturing simulations are performed to show the model robustness and to illustrate how problem parameters such as injection rate and rock permeability affect the hydraulic fracturing variables i.e. injection pressure, fracture aperture and fracture length. The results show the impact of partial saturation on leak-off and the fact that single-phase models may underestimate the leak-off.
Modeling and controlling of a flexible hydraulic manipulator
Institute of Scientific and Technical Information of China (English)
LI Guang; WU Min
2005-01-01
A mathematical model was developed combining the dynamics of an Euler-Bernoulli beam, described by the assumed-mode method and hydraulic circuit dynamics. Only one matrix, termed drive Jacobian, was needed in the modeling of interaction between hydraulic circuit and flexible manipulator mechanism. Furthermore, a new robust controller based on mentioned above dynamic model was also considered to regulate both flexural vibrations and rigid body motion. The proposed controller combined sliding mode and backstepping techniques to deal with the nonlinear system with uncertainties. The sliding mode control was used to achieve an asymptotic joint angle and vibration regulation by providing a virtual force while the backstepping technique was used to regulate the spool position of a hydraulic valve to provide the required control force. Simulation results are presented to show the stabilizing effect and robustness of this control strategy.
Measurement and modeling of unsaturated hydraulic conductivity: Chapter 21
Perkins, Kim S.; Elango, Lakshmanan
2011-01-01
The unsaturated zone plays an extremely important hydrologic role that influences water quality and quantity, ecosystem function and health, the connection between atmospheric and terrestrial processes, nutrient cycling, soil development, and natural hazards such as flooding and landslides. Unsaturated hydraulic conductivity is one of the main properties considered to govern flow; however it is very difficult to measure accurately. Knowledge of the highly nonlinear relationship between unsaturated hydraulic conductivity (K) and volumetric water content () is required for widely-used models of water flow and solute transport processes in the unsaturated zone. Measurement of unsaturated hydraulic conductivity of sediments is costly and time consuming, therefore use of models that estimate this property from more easily measured bulk-physical properties is common. In hydrologic studies, calculations based on property-transfer models informed by hydraulic property databases are often used in lieu of measured data from the site of interest. Reliance on database-informed predicted values with the use of neural networks has become increasingly common. Hydraulic properties predicted using databases may be adequate in some applications, but not others.
Effects of model layer simplification using composite hydraulic properties
Kuniansky, Eve L.; Sepulveda, Nicasio; Elango, Lakshmanan
2011-01-01
Groundwater provides much of the fresh drinking water to more than 1.5 billion people in the world (Clarke et al., 1996) and in the United States more that 50 percent of citizens rely on groundwater for drinking water (Solley et al., 1998). As aquifer systems are developed for water supply, the hydrologic system is changed. Water pumped from the aquifer system initially can come from some combination of inducing more recharge, water permanently removed from storage, and decreased groundwater discharge. Once a new equilibrium is achieved, all of the pumpage must come from induced recharge and decreased discharge (Alley et al., 1999). Further development of groundwater resources may result in reductions of surface water runoff and base flows. Competing demands for groundwater resources require good management. Adequate data to characterize the aquifers and confining units of the system, like hydrologic boundaries, groundwater levels, streamflow, and groundwater pumping and climatic data for recharge estimation are to be collected in order to quantify the effects of groundwater withdrawals on wetlands, streams, and lakes. Once collected, three-dimensional (3D) groundwater flow models can be developed and calibrated and used as a tool for groundwater management. The main hydraulic parameters that comprise a regional or subregional model of an aquifer system are the hydraulic conductivity and storage properties of the aquifers and confining units (hydrogeologic units) that confine the system. Many 3D groundwater flow models used to help assess groundwater/surface-water interactions require calculating ?effective? or composite hydraulic properties of multilayered lithologic units within a hydrogeologic unit. The calculation of composite hydraulic properties stems from the need to characterize groundwater flow using coarse model layering in order to reduce simulation times while still representing the flow through the system accurately. The accuracy of flow models with
Modeling multidomain hydraulic properties of shrink-swell soils
Stewart, Ryan D.; Abou Najm, Majdi R.; Rupp, David E.; Selker, John S.
2016-10-01
Shrink-swell soils crack and become compacted as they dry, changing properties such as bulk density and hydraulic conductivity. Multidomain models divide soil into independent realms that allow soil cracks to be incorporated into classical flow and transport models. Incongruously, most applications of multidomain models assume that the porosity distributions, bulk density, and effective saturated hydraulic conductivity of the soil are constant. This study builds on a recently derived soil shrinkage model to develop a new multidomain, dual-permeability model that can accurately predict variations in soil hydraulic properties due to dynamic changes in crack size and connectivity. The model only requires estimates of soil gravimetric water content and a minimal set of parameters, all of which can be determined using laboratory and/or field measurements. We apply the model to eight clayey soils, and demonstrate its ability to quantify variations in volumetric water content (as can be determined during measurement of a soil water characteristic curve) and transient saturated hydraulic conductivity, Ks (as can be measured using infiltration tests). The proposed model is able to capture observed variations in Ks of one to more than two orders of magnitude. In contrast, other dual-permeability models assume that Ks is constant, resulting in the potential for large error when predicting water movement through shrink-swell soils. Overall, the multidomain model presented here successfully quantifies fluctuations in the hydraulic properties of shrink-swell soil matrices, and are suitable for use in physical flow and transport models based on Darcy's Law, the Richards Equation, and the advection-dispersion equation.
Effects of model layer simplification using composite hydraulic properties
Sepulveda, Nicasio; Kuniansky, Eve L.
2010-01-01
The effects of simplifying hydraulic property layering within an unconfined aquifer and the underlying confining unit were assessed. The hydraulic properties of lithologic units within the unconfined aquifer and confining unit were computed by analyzing the aquifer-test data using radial, axisymmetric two-dimensional (2D) flow. Time-varying recharge to the unconfined aquifer and pumping from the confined Upper Floridan aquifer (USA) were simulated using 3D flow. Conceptual flow models were developed by gradually reducing the number of lithologic units in the unconfined aquifer and confining unit by calculating composite hydraulic properties for the simplified lithologic units. Composite hydraulic properties were calculated using either thickness-weighted averages or inverse modeling using regression-based parameter estimation. No significant residuals were simulated when all lithologic units comprising the unconfined aquifer were simulated as one layer. The largest residuals occurred when the unconfined aquifer and confining unit were aggregated into a single layer (quasi-3D), with residuals over 100% for the leakage rates to the confined aquifer and the heads in the confining unit. Residuals increased with contrasts in vertical hydraulic conductivity between the unconfined aquifer and confining unit. Residuals increased when the constant-head boundary at the bottom of the Upper Floridan aquifer was replaced with a no-flow boundary.
Interactions between roughness and topography in hydraulic models
Casas Planes, María Ángeles
2007-01-01
Analysis of river flow using hydraulic modelling and its implications in derived environ-mental applications are inextricably connected with the way in which the river boundary shape is represented. This relationship is scale-dependent upon the modelling resolution which in turn determines the importance of a subscale performance of the model and the way subscale (surface and flow) processes are parameterised. Commonly, the subscale behaviour of the model relies upon a roughness parameterisat...
Process description of SWQN : A simplified hydraulic model
Smit, A.A.M.F.R.; Siderius, C.; Gerven, van L.P.A.
2009-01-01
SWQN is a simplified hydraulic model for surface water systems which computes water levels and flows in a network of nodes labelled as ‘volumes’ and segments labelled as ‘connectors’. The user can specify a variety of connectors like open water courses or structures such as weirs, gates, culverts or
Nonlinear Model-Based Fault Detection for a Hydraulic Actuator
Van Eykeren, L.; Chu, Q.P.
2011-01-01
This paper presents a model-based fault detection algorithm for a specific fault scenario of the ADDSAFE project. The fault considered is the disconnection of a control surface from its hydraulic actuator. Detecting this type of fault as fast as possible helps to operate an aircraft more cost effect
Process description of SWQN : A simplified hydraulic model
Smit, A.A.M.F.R.; Siderius, C.; Gerven, van L.P.A.
2009-01-01
SWQN is a simplified hydraulic model for surface water systems which computes water levels and flows in a network of nodes labelled as ‘volumes’ and segments labelled as ‘connectors’. The user can specify a variety of connectors like open water courses or structures such as weirs, gates, culverts or
Thermal-hydraulic modeling of reactivity accidents in MTR reactors
Directory of Open Access Journals (Sweden)
Khater Hany
2006-01-01
Full Text Available This paper describes the development of a dynamic model for the thermal-hydraulic analysis of MTR research reactors during a reactivity insertion accident. The model is formulated for coupling reactor kinetics with feedback reactivity and reactor core thermal-hydraulics. To represent the reactor core, two types of channels are considered, average and hot channels. The developed computer program is compiled and executed on a personal computer, using the FORTRAN language. The model is validated by safety-related benchmark calculations for MTR-TYPE reactors of IAEA 10 MW generic reactor for both slow and fast reactivity insertion transients. A good agreement is shown between the present model and the benchmark calculations. Then, the model is used for simulating the uncontrolled withdrawal of a control rod of an ETRR-2 reactor in transient with over power scram trip. The model results for ETRR-2 are analyzed and discussed.
Thermal hydraulic model descrition of TASS/SMR
Energy Technology Data Exchange (ETDEWEB)
Yoon, Han Young; Kim, H. C.; Chung, Y. J.; Lim, H. S.; Yang, S. H
2001-04-01
The TASS/SMR code has been developed for the safety analysis of SMART. The governing equations were applied only to the primary coolant system in TASS which had been developed at KAERI. In TASS/SMR, the solution method is improved so that the primary and secondary coolant systems are solved simultaneously. Besides the solution method, thermal-hydraulic models are incorporated, in TASS/SMR, such as non-condensible gas model, helical steam generator heat transfer model, and passive residual heat removal system (PRHRS) heat transfer model for the application to SMART. The governing equtions of TASS/SMR are based on the drift-flux model so that the accidents and transients accompaning with two-phase flow can be analized. This report describes the governing equations and solution methods used in TASS/SMR and also includes the description for the thermal hydraulic models for SMART design.
Development of a hydraulic model of the human systemic circulation
Sharp, M. K.; Dharmalingham, R. K.
1999-01-01
Physical and numeric models of the human circulation are constructed for a number of objectives, including studies and training in physiologic control, interpretation of clinical observations, and testing of prosthetic cardiovascular devices. For many of these purposes it is important to quantitatively validate the dynamic response of the models in terms of the input impedance (Z = oscillatory pressure/oscillatory flow). To address this need, the authors developed an improved physical model. Using a computer study, the authors first identified the configuration of lumped parameter elements in a model of the systemic circulation; the result was a good match with human aortic input impedance with a minimum number of elements. Design, construction, and testing of a hydraulic model analogous to the computer model followed. Numeric results showed that a three element model with two resistors and one compliance produced reasonable matching without undue complication. The subsequent analogous hydraulic model included adjustable resistors incorporating a sliding plate to vary the flow area through a porous material and an adjustable compliance consisting of a variable-volume air chamber. The response of the hydraulic model compared favorably with other circulation models.
State of the art hydraulic turbine model test
Fabre, Violaine; Duparchy, Alexandre; Andre, Francois; Larroze, Pierre-Yves
2016-11-01
Model tests are essential in hydraulic turbine development and related fields. The methods and technologies used to perform these tests show constant progress and provide access to further information. In addition, due to its contractual nature, the test demand evolves continuously in terms of quantity and accuracy. Keeping in mind that the principal aim of model testing is the transposition of the model measurements to the real machine, the measurements should be performed accurately, and a critical analysis of the model test results is required to distinguish the transposable hydraulic phenomena from the test rig interactions. Although the resonances’ effects are known and described in the IEC standard, their identification is difficult. Leaning on a strong experience of model testing, we will illustrate with a few examples of how to identify the potential problems induced by the test rig. This paper contains some of our best practices to obtain the most accurate, relevant, and independent test-rig measurements.
Numerical modeling of consolidation processes in hydraulically deposited soils
Brink, Nicholas Robert
Hydraulically deposited soils are encountered in many common engineering applications including mine tailing and geotextile tube fills, though the consolidation process for such soils is highly nonlinear and requires the use of advanced numerical techniques to provide accurate predictions. Several commercially available finite element codes poses the ability to model soil consolidation, and it was the goal of this research to assess the ability of two of these codes, ABAQUS and PLAXIS, to model the large-strain, two-dimensional consolidation processes which occur in hydraulically deposited soils. A series of one- and two-dimensionally drained rectangular models were first created to assess the limitations of ABAQUS and PLAXIS when modeling consolidation of highly compressible soils. Then, geotextile tube and TSF models were created to represent actual scenarios which might be encountered in engineering practice. Several limitations were discovered, including the existence of a minimum preconsolidation stress below which numerical solutions become unstable.
Hydraulic Model Tests on Modified Wave Dragon
DEFF Research Database (Denmark)
Hald, Tue; Lynggaard, Jakob
A floating model of the Wave Dragon (WD) was built in autumn 1998 by the Danish Maritime Institute in scale 1:50, see Sørensen and Friis-Madsen (1999) for reference. This model was subjected to a series of model tests and subsequent modifications at Aalborg University and in the following...... are found in Hald and Lynggaard (2001). Model tests and reconstruction are carried out during the phase 3 project: ”Wave Dragon. Reconstruction of an existing model in scale 1:50 and sequentiel tests of changes to the model geometry and mass distribution parameters” sponsored by the Danish Energy Agency...
Modelling and Simulation of Mobile Hydraulic Crane with Telescopic Arm
DEFF Research Database (Denmark)
Nielsen, Brian; Pedersen, Henrik Clemmensen; Andersen, Torben Ole
2005-01-01
paper a model of a loader crane with a flexible telescopic arm is presented, which may be used for evaluating control strategies. The telescopic arm is operated by four actuators connected hydraulically by a parallel circuit. The operating sequences of the individual actuators is therefore...... not controllable, but depends on the flow from the common control valve, flow resistances between the actuators and friction. The presented model incorporates structural flexibility of the telescopic arm and is capable of describing the dynamic behaviour of both the hydraulic and the mechanical system, including...... the relative movement of the individual mechanical bodies in the telescopic arm. The model is verified through comparisons between simulated and measured results for various operating conditions....
Nonlinear mathematical modeling and sensitivity analysis of hydraulic drive unit
Kong, Xiangdong; Yu, Bin; Quan, Lingxiao; Ba, Kaixian; Wu, Liujie
2015-09-01
The previous sensitivity analysis researches are not accurate enough and also have the limited reference value, because those mathematical models are relatively simple and the change of the load and the initial displacement changes of the piston are ignored, even experiment verification is not conducted. Therefore, in view of deficiencies above, a nonlinear mathematical model is established in this paper, including dynamic characteristics of servo valve, nonlinear characteristics of pressure-flow, initial displacement of servo cylinder piston and friction nonlinearity. The transfer function block diagram is built for the hydraulic drive unit closed loop position control, as well as the state equations. Through deriving the time-varying coefficient items matrix and time-varying free items matrix of sensitivity equations respectively, the expression of sensitivity equations based on the nonlinear mathematical model are obtained. According to structure parameters of hydraulic drive unit, working parameters, fluid transmission characteristics and measured friction-velocity curves, the simulation analysis of hydraulic drive unit is completed on the MATLAB/Simulink simulation platform with the displacement step 2 mm, 5 mm and 10 mm, respectively. The simulation results indicate that the developed nonlinear mathematical model is sufficient by comparing the characteristic curves of experimental step response and simulation step response under different constant load. Then, the sensitivity function time-history curves of seventeen parameters are obtained, basing on each state vector time-history curve of step response characteristic. The maximum value of displacement variation percentage and the sum of displacement variation absolute values in the sampling time are both taken as sensitivity indexes. The sensitivity indexes values above are calculated and shown visually in histograms under different working conditions, and change rules are analyzed. Then the sensitivity
Modeling of Propagation of Interacting Cracks Under Hydraulic Pressure Gradient
Energy Technology Data Exchange (ETDEWEB)
Huang, Hai [Idaho National Laboratory; Mattson, Earl Douglas [Idaho National Laboratory; Podgorney, Robert Karl [Idaho National Laboratory
2015-04-01
A robust and reliable numerical model for fracture initiation and propagation, which includes the interactions among propagating fractures and the coupling between deformation, fracturing and fluid flow in fracture apertures and in the permeable rock matrix, would be an important tool for developing a better understanding of fracturing behaviors of crystalline brittle rocks driven by thermal and (or) hydraulic pressure gradients. In this paper, we present a physics-based hydraulic fracturing simulator based on coupling a quasi-static discrete element model (DEM) for deformation and fracturing with conjugate lattice network flow model for fluid flow in both fractures and porous matrix. Fracturing is represented explicitly by removing broken bonds from the network to represent microcracks. Initiation of new microfractures and growth and coalescence of the microcracks leads to the formation of macroscopic fractures when external and/or internal loads are applied. The coupled DEM-network flow model reproduces realistic growth pattern of hydraulic fractures. In particular, simulation results of perforated horizontal wellbore clearly demonstrate that elastic interactions among multiple propagating fractures, fluid viscosity, strong coupling between fluid pressure fluctuations within fractures and fracturing, and lower length scale heterogeneities, collectively lead to complicated fracturing patterns.
Hydraulic modelling of drinking water treatment plant operations
Directory of Open Access Journals (Sweden)
L. C. Rietveld
2009-06-01
Full Text Available The flow through a unit of a drinking water treatment plant is one of the most important parameters in terms of a unit's effectiveness. In the present paper, a new EPAnet library is presented with the typical hydraulic elements for drinking water treatment processes well abstraction, rapid sand filtration and cascade and tower aeration. Using this treatment step library, a hydraulic model was set up, calibrated and validated for the drinking water treatment plant Harderbroek. With the actual valve position and pump speeds, the flows were calculated through the several treatment steps. A case shows the use of the model to calculate the new setpoints for the current frequency converters of the effluent pumps during a filter backwash.
Modeling, Optimization & Control of Hydraulic Networks
DEFF Research Database (Denmark)
Tahavori, Maryamsadat
2014-01-01
to check if the network is controllable. Afterward the pressure control problem in water supply systems is formulated as an optimal control problem. The goal is to minimize the power consumption in pumps and also to regulate the pressure drop at the end-users to a desired value. The formulated optimal...... in water network is pressure management. By reducing the pressure in the water network, the leakage can be reduced significantly. Also it reduces the amount of energy consumption in water networks. The primary purpose of this work is to develop control algorithms for pressure control in water supply...... systems. To have better understanding of water leakage, to control pressure and leakage effectively and for optimal design of water supply system, suitable modeling is an important prerequisite. Therefore a model with the main objective of pressure control and consequently leakage reduction is presented...
Phase-field modeling of hydraulic fracture
Wilson, Zachary A.; Landis, Chad M.
2016-11-01
In this work a theoretical framework implementing the phase-field approach to fracture is used to couple the physics of flow through porous media and cracks with the mechanics of fracture. The main modeling challenge addressed in this work, which is a challenge for all diffuse crack representations, is on how to allow for the flow of fluid and the action of fluid pressure on the aggregate within the diffuse damage zone of the cracks. The theory is constructed by presenting the general physical balance laws and conducting a consistent thermodynamic analysis to constrain the constitutive relationships. Constitutive equations that reproduce the desired responses at the various limits of the phase-field parameter are proposed in order to capture Darcy-type flow in the intact porous medium and Stokes-type flow within open cracks. A finite element formulation for the solution of the governing model equations is presented and discussed. Finally, the theoretical and numerical model is shown to compare favorably to several important analytical solutions. More complex and interesting calculations are also presented to illustrate some of the advantageous features of the approach.
Advanced geothermal hydraulics model -- Phase 1 final report, Part 2
Energy Technology Data Exchange (ETDEWEB)
W. Zheng; J. Fu; W. C. Maurer
1999-07-01
An advanced geothermal well hydraulics model (GEODRIL) is being developed to accurately calculate bottom-hole conditions in these hot wells. In Phase 1, real-time monitoring and other improvements were added to GEODRIL. In Phase 2, GEODRIL will be integrated into Marconi's Intelligent Drilling Monitor (IDM) that will use artificial intelligence to detect lost circulation, fluid influxes and other circulation problems in geothermal wells. This software platform has potential for significantly reducing geothermal drilling costs.
The analysis of thermal-hydraulic models in MELCOR code
Energy Technology Data Exchange (ETDEWEB)
Kim, M. H.; Hur, C.; Kim, D. K.; Cho, H. J. [POhang Univ., of Science and TECHnology, Pohang (Korea, Republic of)
1996-07-15
The objective of the present work is to verify the prediction and analysis capability of MELCOR code about the progression of severe accidents in light water reactor and also to evaluate appropriateness of thermal-hydraulic models used in MELCOR code. Comparing the results of experiment and calculation with MELCOR code is carried out to achieve the above objective. Specially, the comparison between the CORA-13 experiment and the MELCOR code calculation was performed.
Project W-320 thermal hydraulic model benchmarking and baselining
Energy Technology Data Exchange (ETDEWEB)
Sathyanarayana, K.
1998-09-28
Project W-320 will be retrieving waste from Tank 241-C-106 and transferring the waste to Tank 241-AY-102. Waste in both tanks must be maintained below applicable thermal limits during and following the waste transfer. Thermal hydraulic process control models will be used for process control of the thermal limits. This report documents the process control models and presents a benchmarking of the models with data from Tanks 241-C-106 and 241-AY-102. Revision 1 of this report will provide a baselining of the models in preparation for the initiation of sluicing.
Simple Predictive Models for Saturated Hydraulic Conductivity of Technosands
DEFF Research Database (Denmark)
Arthur, Emmanuel; Razzaghi, Fatemeh; Møldrup, Per
2012-01-01
Accurate estimation of saturated hydraulic conductivity (Ks) of technosands (gravel-free, coarse sands with negligible organic matter content) is important for irrigation and drainage management of athletic fields and golf courses. In this study, we developed two simple models for predicting Ks......-connectivity parameter (m) obtained for pure coarse sand after fitting to measured Ks data was 1.68 for both models and in good agreement with m values obtained from recent solute and gas diffusion studies. Both the modified K-C and R-C models are easy to use and require limited parameter input, and both models gave...
Institute of Scientific and Technical Information of China (English)
Yang Haiwei; Zhan Yongqi; Qiao Junwei; Shi Guanglin
2003-01-01
The dynamic working process of 52SFZ-140-207B type of hydraulic bumper is analyzed. The modeling method using architecture-based neural networks is introduced. Using this modeling method, the dynamic model of the hydraulic bumper is established; Based on this model the structural parameters of the hydraulic bumper are optimized with Genetic algorithm. The result shows that the performance of the dynamic model is close to that of the hydraulic bumper, and the dynamic performance of the hydraulic bumper is improved through parameter optimization.
Monitoring and modeling the soil hydraulic behavior in stony soils
Dragonetti, Giovanna; Lamaddalena, Nicola; Comegna, Alessandro; Coppola, Antonio
2014-05-01
Describing the soil hydrological behavior at applicative scales remains a complex task, mainly because of the spatial heterogeneity of the vadose zone. Addressing the impact of the unsaturated zone heterogeneity involves measuring and/or modeling water content evolution with fine spatial and temporal resolution. The presence of stones introduces difficulties for both the measurement of the water content and the soil hydraulic properties. In this context, the main objective of this study was to assess the role of stones on TDR-based water content measurements, as well as on the pattern of variability of simulated water contents at field-scale during water infiltration, drainage and evaporation processes. Also, the role of stones was evaluated as one possible explanation of the differences frequently observed between the measured hydraulic behavior and that estimated by using pedotransfer functions.
Views on the future of thermal hydraulic modeling
Energy Technology Data Exchange (ETDEWEB)
Ishii, M. [Purdue Univ., West Lafayette, IN (United States)
1997-07-01
It is essential for the U.S. NRC to sustain the highest level of the thermal-hydraulics and reactor safety research expertise and continuously improve their accident analysis capability. Such expertise should span over four different areas which are strongly related to each other. These are: (1) Reactor Safety Code Development, (2) Two-phase Flow Modeling, (3) Instrumentation and Fundamental Experimental Research, and (4) Separate Effect and Integral Test. The NRC is already considering a new effort in the area of advanced thermal-hydraulics effort. Its success largely depends on the availability of a significantly improved two-phase flow formulation and constitutive relations supported by detailed experimental data. Therefore, it is recommended that the NRC start significant research efforts in the areas of two-phase flow modeling, instrumentation, basic and separate effect experiments which should be pursued systematically and with clearly defined objectives. It is desirable that some international program is developed in this area. This paper is concentrated on those items in the thermal-hydraulic area which eventually determine the quality of future accident analysis codes.
Hydraulic fracture propagation modeling and data-based fracture identification
Zhou, Jing
Successful shale gas and tight oil production is enabled by the engineering innovation of horizontal drilling and hydraulic fracturing. Hydraulically induced fractures will most likely deviate from the bi-wing planar pattern and generate complex fracture networks due to mechanical interactions and reservoir heterogeneity, both of which render the conventional fracture simulators insufficient to characterize the fractured reservoir. Moreover, in reservoirs with ultra-low permeability, the natural fractures are widely distributed, which will result in hydraulic fractures branching and merging at the interface and consequently lead to the creation of more complex fracture networks. Thus, developing a reliable hydraulic fracturing simulator, including both mechanical interaction and fluid flow, is critical in maximizing hydrocarbon recovery and optimizing fracture/well design and completion strategy in multistage horizontal wells. A novel fully coupled reservoir flow and geomechanics model based on the dual-lattice system is developed to simulate multiple nonplanar fractures' propagation in both homogeneous and heterogeneous reservoirs with or without pre-existing natural fractures. Initiation, growth, and coalescence of the microcracks will lead to the generation of macroscopic fractures, which is explicitly mimicked by failure and removal of bonds between particles from the discrete element network. This physics-based modeling approach leads to realistic fracture patterns without using the empirical rock failure and fracture propagation criteria required in conventional continuum methods. Based on this model, a sensitivity study is performed to investigate the effects of perforation spacing, in-situ stress anisotropy, rock properties (Young's modulus, Poisson's ratio, and compressive strength), fluid properties, and natural fracture properties on hydraulic fracture propagation. In addition, since reservoirs are buried thousands of feet below the surface, the
Modeling soil detachment capacity by rill flow using hydraulic parameters
Wang, Dongdong; Wang, Zhanli; Shen, Nan; Chen, Hao
2016-04-01
The relationship between soil detachment capacity (Dc) by rill flow and hydraulic parameters (e.g., flow velocity, shear stress, unit stream power, stream power, and unit energy) at low flow rates is investigated to establish an accurate experimental model. Experiments are conducted using a 4 × 0.1 m rill hydraulic flume with a constant artificial roughness on the flume bed. The flow rates range from 0.22 × 10-3 m2 s-1 to 0.67 × 10-3 m2 s-1, and the slope gradients vary from 15.8% to 38.4%. Regression analysis indicates that the Dc by rill flow can be predicted using the linear equations of flow velocity, stream power, unit stream power, and unit energy. Dc by rill flow that is fitted to shear stress can be predicted with a power function equation. Predictions based on flow velocity, unit energy, and stream power are powerful, but those based on shear stress, especially on unit stream power, are relatively poor. The prediction based on flow velocity provides the best estimates of Dc by rill flow because of the simplicity and availability of its measurements. Owing to error in measuring flow velocity at low flow rates, the predictive abilities of Dc by rill flow using all hydraulic parameters are relatively lower in this study compared with the results of previous research. The measuring accuracy of experiments for flow velocity should be improved in future research.
Using Hydraulic Network Models to Teach Electric Circuit Principles
Jones, Irvin; EERC (Engineering Education Research Center) Collaboration
2013-11-01
Unlike other engineering disciplines, teaching electric circuit principles is difficult for some students because there isn't a visual context to rely on. So concepts such as electric potential, current, resistance, capacitance, and inductance have little meaning outside of their definition and the derived mathematical relationships. As a work in progress, we are developing a tool to support teaching, learning, and research of electric circuits. The tool will allow the user to design, build, and operate electric circuits in the form of hydraulic networks. We believe that this system will promote greater learning of electric circuit principles by visually realizing the conceptual and abstract concepts of electric circuits. Furthermore, as a teaching and learning tool, the hydraulic network system can be used to teach and improve comprehension of electrical principles in K through 12 classrooms and in cross-disciplinary environments such as Bioengineering, Mechanical Engineering, Industrial Engineering, and Aeronautical Engineering. As a research tool, the hydraulic network can model and simulate micro/nano bio-electro-chemical systems. Organization within the Swanson School of Engineering at the University of Pittsburgh.
OPTIMUM DESIGN AND NON-LINEAR MODEL OF POWERPLANT HYDRAULIC MOUNT SYSTEM
Institute of Scientific and Technical Information of China (English)
Shi Wenku; Min Haitao; Dang Zhaolong
2003-01-01
6-DOF non-linear mechanics model of powerplant hydraulic mount system is established. Optimum design of the powerplant hydraulic mount system is made with the hydraulic mount parameters as variables and with uncoupling of energy, rational disposition of nature frequency and minimum of reactive force at mount's location as objective functions. And based on the optimum design, software named ODPHMS (optimum design of powerplant hydraulic mount system) used in powerplant mount system optimum design is developed.
Energy Technology Data Exchange (ETDEWEB)
Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States); Gromov, Roman [Argonne National Lab. (ANL), Argonne, IL (United States); Makarashvili, Vakho [Argonne National Lab. (ANL), Argonne, IL (United States); Heltemes, Thad [Argonne National Lab. (ANL), Argonne, IL (United States); Sun, Zaijing [Argonne National Lab. (ANL), Argonne, IL (United States); Wardle, Kent E. [Argonne National Lab. (ANL), Argonne, IL (United States); Bailey, James [Argonne National Lab. (ANL), Argonne, IL (United States); Quigley, Kevin [Argonne National Lab. (ANL), Argonne, IL (United States); Stepinski, Dominique [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George [Argonne National Lab. (ANL), Argonne, IL (United States)
2014-10-01
Argonne is assisting SHINE Medical Technologies in developing SHINE, a system for producing fission-product ^{99}Mo using a D/T-accelerator to produce fission in a non-critical target solution of aqueous uranyl sulfate. We have developed an experimental setup for studying thermal-hydraulics and bubble formation in the uranyl sulfate solution to simulate conditions expected in the SHINE target solution during irradiation. A direct electron beam from the linac accelerator will be used to irradiate a 20 L solution (sector of the solution vessel). Because the solution will undergo radiolytic decomposition, we will be able to study bubble formation and dynamics and effects of convection and temperature on bubble behavior. These experiments will serve as a verification/ validation tool for the thermal-hydraulic model. Utilization of the direct electron beam for irradiation allows homogeneous heating of a large solution volume and simplifies observation of the bubble dynamics simultaneously with thermal-hydraulic data collection, which will complement data collected during operation of the miniSHINE experiment. Irradiation will be conducted using a 30-40 MeV electron beam from the high-power linac accelerator. The total electron-beam power will be 20 kW, which will yield a power density on the order of 1 kW/L. The solution volume will be cooled on the front and back surfaces and central tube to mimic the geometry of the proposed SHINE solution vessel. Also, multiple thermocouples will be inserted into the solution vessel to map thermal profiles. The experimental design is now complete, and installation and testing are in progress.
Evaluating models for predicting hydraulic characteristics of layered soils
Mavimbela, S. S. W.; van Rensburg, L. D.
2012-01-01
Soil water characteristic curve (SWCC) and unsaturated hydraulic conductivity (K-coefficient) are critical hydraulic properties governing soil water activity on layered soils. Sustainable soil water conservation would not be possible without accurate knowledge of these hydraulic properties. Infield rainwater harvesting (IRWH) is one conservation technique adopted to improve the soil water regime of a number of clay soils found in the semi arid areas of Free State province of South Africa. Given that SWCC is much easier to measure, most soil water studies rely on SWCC information to predict in-situ K-coefficients. This work validated this practice on the Tukulu, Sepane and Swartland layered soil profiles. The measured SWCC was first described using Brooks and Corey (1964), van Genuchten (1980) and Kasugi (1996) parametric models. The conductivity functions of these models were then required to fit in-situ based K-coefficients derived from instantaneous profile method (IPM). The same K-coefficient was also fitted by HYDRUS 1-D using optimised SWCC parameters. Although all parametric models fitted the measured SWCC fairly well their corresponding conductivity functions could not do the same when fitting the in-situ based K-coefficients. Overestimates of more than 2 orders of magnitude especially at low soil water content (SWC) were observed. This phenomenon was pronounced among the upper horizons that overlaid a clayey horizon. However, optimized α and n parameters using HYDRUS 1-D showed remarkable agreement between fitted and in-situ K-coefficient with root sum of squares error (RMSE) recording values not exceeding unity. During this exercise the Brooks and Corey was replaced by modified van Genuchten model (Vogel and Cislerova, 1988) since it failed to produce unique inverse solutions. The models performance appeared to be soil specific with van Genuchten-Mualem (1980) performing fairly well on the Orthic and neucutanic horizons while its modified form fitted very
Evaluating models for predicting hydraulic characteristics of layered soils
Directory of Open Access Journals (Sweden)
S. S. W. Mavimbela
2012-01-01
Full Text Available Soil water characteristic curve (SWCC and unsaturated hydraulic conductivity (K-coefficient are critical hydraulic properties governing soil water activity on layered soils. Sustainable soil water conservation would not be possible without accurate knowledge of these hydraulic properties. Infield rainwater harvesting (IRWH is one conservation technique adopted to improve the soil water regime of a number of clay soils found in the semi arid areas of Free State province of South Africa. Given that SWCC is much easier to measure, most soil water studies rely on SWCC information to predict in-situ K-coefficients. This work validated this practice on the Tukulu, Sepane and Swartland layered soil profiles. The measured SWCC was first described using Brooks and Corey (1964, van Genuchten (1980 and Kasugi (1996 parametric models. The conductivity functions of these models were then required to fit in-situ based K-coefficients derived from instantaneous profile method (IPM. The same K-coefficient was also fitted by HYDRUS 1-D using optimised SWCC parameters. Although all parametric models fitted the measured SWCC fairly well their corresponding conductivity functions could not do the same when fitting the in-situ based K-coefficients. Overestimates of more than 2 orders of magnitude especially at low soil water content (SWC were observed. This phenomenon was pronounced among the upper horizons that overlaid a clayey horizon. However, optimized α and n parameters using HYDRUS 1-D showed remarkable agreement between fitted and in-situ K-coefficient with root sum of squares error (RMSE recording values not exceeding unity. During this exercise the Brooks and Corey was replaced by modified van Genuchten model (Vogel and Cislerova, 1988 since it failed to produce unique inverse solutions. The models performance appeared to be soil specific with van Genuchten-Mualem (1980 performing fairly well on the Orthic
A solenoid-based active hydraulic engine mount: modelling, analysis, and verification
Hosseini, Ali
2010-01-01
The focus of this thesis is on the design, modelling, identification, simulation, and experimental verification of a low-cost solenoid-based active hydraulic engine mount. To build an active engine mount, a commercial On-Off solenoid is modified to be used as an actuator and it is embedded inside a hydraulic engine mount. The hydraulic engine mount is modelled and tested, solenoid actuator is modelled and identified, and finally the models were integrated to obtain the analytical model of the...
Developed hydraulic simulation model for water pipeline networks
Directory of Open Access Journals (Sweden)
A. Ayad
2013-03-01
Full Text Available A numerical method that uses linear graph theory is presented for both steady state, and extended period simulation in a pipe network including its hydraulic components (pumps, valves, junctions, etc.. The developed model is based on the Extended Linear Graph Theory (ELGT technique. This technique is modified to include new network components such as flow control valves and tanks. The technique also expanded for extended period simulation (EPS. A newly modified method for the calculation of updated flows improving the convergence rate is being introduced. Both benchmarks, ad Actual networks are analyzed to check the reliability of the proposed method. The results reveal the finer performance of the proposed method.
First wall thermal hydraulic models for fusion blankets
Energy Technology Data Exchange (ETDEWEB)
Fillo, J A
1980-01-01
Subject to normal and off-normal reactor conditions, thermal hydraulic models of first walls, e.g., a thermal mass barrier, a tubular shield, and a radiating liner are reviewed. Under normal operation the plasma behaves as expected in a predicted way for transient and steady-state conditions. The most severe thermal loading on the first wall occurs when the plasma becomes unstable and dumps its energy on the wall in a very short period of time (milliseconds). Depending on the plasma dump time and area over which the energy is deposited may result in melting of the first wall surface, and if the temperature is high enough, vaporization.
"GRAY-BOX" MODELING METHOD AND PARAMETERS IDENTIFICATION FOR LARGE-SCALE HYDRAULIC SYSTEM
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Modeling and digital simulation is an effective method to analyze the dynamic characteristics of hydraulic system. It is difficult to determine some performance parameters in the hydraulic system by means of currently used modeling methods. The "gray-box" modeling method for large-scale hydraulic system is introduced. The principle of the method, the submodels of some components and the parameters identification of components or subsystem are researched.
Intelligent Hydraulic Actuator and Exp-based Modelling of Losses in Pumps and .
DEFF Research Database (Denmark)
Zhang, Muzhi
A intelligent fuzzy logic self-organising PD+I controller for a gearrotor hydraulic motor was developed and evaluated. Furthermore, a experimental-based modelling methods with a new software tool 'Dynamodata' for modelling of losses in hydraulic motors and pumps was developed.......A intelligent fuzzy logic self-organising PD+I controller for a gearrotor hydraulic motor was developed and evaluated. Furthermore, a experimental-based modelling methods with a new software tool 'Dynamodata' for modelling of losses in hydraulic motors and pumps was developed....
Model based monitoring of wellbore hydraulics for abnormal event detection
Energy Technology Data Exchange (ETDEWEB)
Todorov, Dimitar; Fruhwirth, Rudolf K. [Thonhauser Data Engineering GmbH, Leoben (Austria); Thonhauser, Gerhard [Montanuniversitaet Leoben (Austria)
2013-03-15
With the increasing demand for energy in the last decades, the petroleum industry was forced to push the limits to levels that have never been reached before. Exploring very deep waters, drilling under varying conditions of extreme pressure and temperature and dealing with issues, which involve a new level of understanding, are challenges, which need to be overcome in order to safely and successfully accomplish the planned goals. Operating under such circumstances obligates the driller to be extremely precise in his actions. Even with the driller's extensive experience and training, the possible reaction time is in some cases extremely short. This article discusses the reasons for automatic trouble event recognition systems in the drilling process and how these affect the drilling operations and optimization processes. In this respect a concept of a real time hydraulic monitor will be developed helping the driller to visualize calculations in a plot, showing the pump limitations, the limitations due to the formation fracture gradient and the hole cleaning requirements. Additionally, taking into account the complete wellbore hydraulics and introducing various well behavior models and different algorithms, the system is capable of operating as a real-time indicator for undesired downhole events. (orig.)
Evaluation of some infiltration models and hydraulic parameters
Energy Technology Data Exchange (ETDEWEB)
Haghighi, F.; Gorji, M.; Shorafa, M.; Sarmadian, F.; Mohammadi, M. H.
2010-07-01
The evaluation of infiltration characteristics and some parameters of infiltration models such as sorptivity and final steady infiltration rate in soils are important in agriculture. The aim of this study was to evaluate some of the most common models used to estimate final soil infiltration rate. The equality of final infiltration rate with saturated hydraulic conductivity (Ks) was also tested. Moreover, values of the estimated sorptivity from the Philips model were compared to estimates by selected pedotransfer functions (PTFs). The infiltration experiments used the doublering method on soils with two different land uses in the Taleghan watershed of Tehran province, Iran, from September to October, 2007. The infiltration models of Kostiakov-Lewis, Philip two-term and Horton were fitted to observed infiltration data. Some parameters of the models and the coefficient of determination goodness of fit were estimated using MATLAB software. The results showed that, based on comparing measured and model-estimated infiltration rate using root mean squared error (RMSE), Hortons model gave the best prediction of final infiltration rate in the experimental area. Laboratory measured Ks values gave significant differences and higher values than estimated final infiltration rates from the selected models. The estimated final infiltration rate was not equal to laboratory measured Ks values in the study area. Moreover, the estimated sorptivity factor by Philips model was significantly different to those estimated by selected PTFs. It is suggested that the applicability of PTFs is limited to specific, similar conditions. (Author) 37 refs.
A conceptual model of check dam hydraulics for gully control
Directory of Open Access Journals (Sweden)
C. Castillo
2013-09-01
Full Text Available There is little information in scientific literature regarding the modifications induced by check dam systems in flow regimes in restored gully reaches, despite it being a crucial issue for the design of conservation measures. Here, we develop a conceptual model to classify flow regimes in straight rectangular channels for initial and dam-filling conditions as well as a method of estimating efficiency in order to provide guidelines for optimal design. The model integrates several previous mathematical approaches for assessing the main processes involved (hydraulic jump HJ, impact flow, gradually varied flows. Its performance was compared with the simulations obtained from IBER, a bi-dimensional hydrodynamic model. The impact of check dam spacing (defined by the geometric factor of influence c on efficiency was explored. Eleven main classifications of flow regimes were identified depending on the element and level of influence. The model produced similar results when compared with IBER, but led to higher estimations of HJ and impact lengths. Total influence guaranteed maximum efficiency and HJ control defining the location of the optimal c. Geometric total influence (c = 1 was a valid criterion for the different stages of the structures in a wide range of situations provided that hydraulic roughness conditions remained high within the gully, e.g. through revegetation. Our total influence criterion involved shorter spacing than that habitually recommended in technical manuals for restoration, but was in line with those values found in spontaneous and stable step-pools systems, which might serve as a reference for man-made interventions.
Numerical modeling of concrete hydraulic fracturing with extended finite element method
Institute of Scientific and Technical Information of China (English)
REN QingWen; DONG YuWen; YU TianTang
2009-01-01
The extended finite element method (XFEM) is a new numerical method for modeling discontinuity.Research about numerical modeling for concrete hydraulic fracturing by XFEM is explored. By building the virtual work principle of the fracture problem considering water pressure on the crack surface, the governing equations of XFEM for hydraulic fracture modeling are derived. Implementation of the XFEM for hydraulic fracturing is presented. Finally, the method is verified by two examples and the advan-tages of the XFEM for hydraulic fracturing analysis are displayed.
Numerical modeling of concrete hydraulic fracturing with extended finite element method
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The extended finite element method (XFEM) is a new numerical method for modeling discontinuity. Research about numerical modeling for concrete hydraulic fracturing by XFEM is explored. By building the virtual work principle of the fracture problem considering water pressure on the crack surface, the governing equations of XFEM for hydraulic fracture modeling are derived. Implementation of the XFEM for hydraulic fracturing is presented. Finally, the method is verified by two examples and the advan- tages of the XFEM for hydraulic fracturing analysis are displayed.
submitter Thermal, Hydraulic, and Electromagnetic Modeling of Superconducting Magnet Systems
Bottura, L
2016-01-01
Modeling techniques and tailored computational tools are becoming increasingly relevant to the design and analysis of large-scale superconducting magnet systems. Efficient and reliable tools are useful to provide an optimal forecast of the envelope of operating conditions and margins, which are difficult to test even when a prototype is available. This knowledge can be used to considerably reduce the design margins of the system, and thus the overall cost, or increase reliability during operation. An integrated analysis of a superconducting magnet system is, however, a complex matter, governed by very diverse physics. This paper reviews the wide spectrum of phenomena and provides an estimate of the time scales of thermal, hydraulic, and electromagnetic mechanisms affecting the performance of superconducting magnet systems. The analysis is useful to provide guidelines on how to divide the complex problem into building blocks that can be integrated in a design and analysis framework for a consistent multiphysic...
Modeling and control for hydraulic transmission of unmanned ground vehicle
Institute of Scientific and Technical Information of China (English)
王岩; 张泽; 秦绪情
2014-01-01
Variable pump driving variable motor (VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle (UGV). VPDVM is a dual-input single-output nonlinear system with coupling, which is difficult to control. High pressure automatic variables bang-bang (HABB) was proposed to achieve the desired motor speed. First, the VPDVM nonlinear mathematic model was introduced, then linearized by feedback linearization theory, and the zero-dynamic stability was proved. The HABB control algorithm was proposed for VPDVM, in which the variable motor was controlled by high pressure automatic variables (HA) and the variable pump was controlled by bang-bang. Finally, simulation of VPDVM controlled by HABB was developed. Simulation results demonstrate the HABB can implement the desired motor speed rapidly and has strong robustness against the variations of desired motor speed, load and pump speed.
PHYSICAL MODELING OF HYDRAULIC DESILTATION IN TAPU RESERVOIR
Institute of Scientific and Technical Information of China (English)
Jihn-Sung LAI; Fi-John CHANG
2001-01-01
A movable bed physical model was constructed to investigate hydraulic desiltation by flushing and lateral erosion in the Tapu reservoir, Taiwan. The model scaling is based on the requirement for dynamic similarity of cohesive sediment deposit initiation in flushing processes. For model scaling,flume experiments investigating the initiation of cohesive sediment deposits were carried out to establish the relationship between critical shear stress of the flow and dry density of the deposit.Experiments in the physical model were then performed to measure the variations of the reservoir water level, the outlet discharge and the outflow sediment discharge. The processes of emptying and flushing were observed and analyzed in the main flushing channel. One of the experiments was conducted to simulate the on-site flushing operations on June 11, 1997. The results showed that the total cumulative flushed sediment volume by physical modeling was close to that by numerical simulation. To deal with the floodplain deposits, experiments of lateral erosion as an auxiliary method were also conducted in the physical model to investigate the effectiveness and applicability for the Tapu reservoir.
Intelligent Hydraulic Actuator and Exp-based Modelling of Losses in Pumps and .
DEFF Research Database (Denmark)
Zhang, Muzhi
A intelligent fuzzy logic self-organising PD+I controller for a gearrotor hydraulic motor was developed and evaluated. Furthermore, a experimental-based modelling methods with a new software tool 'Dynamodata' for modelling of losses in hydraulic motors and pumps was developed....
Energy Technology Data Exchange (ETDEWEB)
Suh, Kune Yull; Yoon, Sang Hyuk; Noh, Sang Woo; Lee, Il Suk [Seoul National University, Seoul (Korea)
2002-03-01
This study is concerned with developing a multidimensional flow model required for the system analysis code MARS to more mechanistically simulate a variety of thermal hydraulic phenomena in the nuclear stem supply system. The capability of the MARS code as a thermal hydraulic analysis tool for optimized system design can be expanded by improving the current calculational methods and adding new models. In this study the relevant literature was surveyed on the multidimensional flow models that may potentially be applied to the multidimensional analysis code. Research items were critically reviewed and suggested to better predict the multidimensional thermal hydraulic behavior and to identify test requirements. A small-scale preliminary test was performed in the downcomer formed by two vertical plates to analyze multidimensional flow pattern in a simple geometry. The experimental result may be applied to the code for analysis of the fluid impingement to the reactor downcomer wall. Also, data were collected to find out the controlling parameters for the one-dimensional and multidimensional flow behavior. 22 refs., 40 figs., 7 tabs. (Author)
Bayesian Model Averaging of Artificial Intelligence Models for Hydraulic Conductivity Estimation
Nadiri, A.; Chitsazan, N.; Tsai, F. T.; Asghari Moghaddam, A.
2012-12-01
This research presents a Bayesian artificial intelligence model averaging (BAIMA) method that incorporates multiple artificial intelligence (AI) models to estimate hydraulic conductivity and evaluate estimation uncertainties. Uncertainty in the AI model outputs stems from error in model input as well as non-uniqueness in selecting different AI methods. Using one single AI model tends to bias the estimation and underestimate uncertainty. BAIMA employs Bayesian model averaging (BMA) technique to address the issue of using one single AI model for estimation. BAIMA estimates hydraulic conductivity by averaging the outputs of AI models according to their model weights. In this study, the model weights were determined using the Bayesian information criterion (BIC) that follows the parsimony principle. BAIMA calculates the within-model variances to account for uncertainty propagation from input data to AI model output. Between-model variances are evaluated to account for uncertainty due to model non-uniqueness. We employed Takagi-Sugeno fuzzy logic (TS-FL), artificial neural network (ANN) and neurofuzzy (NF) to estimate hydraulic conductivity for the Tasuj plain aquifer, Iran. BAIMA combined three AI models and produced better fitting than individual models. While NF was expected to be the best AI model owing to its utilization of both TS-FL and ANN models, the NF model is nearly discarded by the parsimony principle. The TS-FL model and the ANN model showed equal importance although their hydraulic conductivity estimates were quite different. This resulted in significant between-model variances that are normally ignored by using one AI model.
Specific features pertinent to modeling of hydraulic systems containing control members
Tverskoy, Yu. S.; Marshalov, E. D.
2014-09-01
The theoretical principles applied for modeling of hydraulic systems fitted with control members that allow a hydraulic line's specific features (topology) to be taken into account are considered. Such modeling opens the possibility to predict the actual flow (throttling) characteristics at early design stages and timely introduce the appropriate corrections in pipeline topology. The modeling problem is solved with the use of generalized thermodynamic analysis methods. The mathematical models of hydraulic systems containing control members are brought to the level of real-time simulation models, which can be used for setting up computation experiments for achieving better performance of automatic closed-loop control systems.
Implicit level set algorithms for modelling hydraulic fracture propagation.
Peirce, A
2016-10-13
Hydraulic fractures are tensile cracks that propagate in pre-stressed solid media due to the injection of a viscous fluid. Developing numerical schemes to model the propagation of these fractures is particularly challenging due to the degenerate, hypersingular nature of the coupled integro-partial differential equations. These equations typically involve a singular free boundary whose velocity can only be determined by evaluating a distinguished limit. This review paper describes a class of numerical schemes that have been developed to use the multiscale asymptotic behaviour typically encountered near the fracture boundary as multiple physical processes compete to determine the evolution of the fracture. The fundamental concepts of locating the free boundary using the tip asymptotics and imposing the tip asymptotic behaviour in a weak form are illustrated in two quite different formulations of the governing equations. These formulations are the displacement discontinuity boundary integral method and the extended finite-element method. Practical issues are also discussed, including new models for proppant transport able to capture 'tip screen-out'; efficient numerical schemes to solve the coupled nonlinear equations; and fast methods to solve resulting linear systems. Numerical examples are provided to illustrate the performance of the numerical schemes. We conclude the paper with open questions for further research. This article is part of the themed issue 'Energy and the subsurface'.
Thermal-Hydraulic Experiments and Modelling for Advanced Nuclear Reactor Systems
Energy Technology Data Exchange (ETDEWEB)
Song, C. H.; Chung, M. K.; Park, C. K. and others
2005-04-15
The objectives of the project are to study thermal hydraulic characteristics of reactor primary system for the verification of the reactor safety and to evaluate new safety concepts of new safety design features. To meet the research goal, several thermal hydraulic experiments were performed and related thermal hydraulic models were developed with the experimental data which were produced through the thermal hydraulic experiments. Followings are main research topics; - Multi-dimensional Phenomena in a Reactor Vessel Downcomer - Condensation Load and Thermal Mixing in the IRWST - Development of Thermal-Hydraulic Models for Two-Phase Flow - Development of Measurement Techniques for Two-Phase Flow - Supercritical Reactor T/H Characteristics Analysis From the above experimental and analytical studies, new safety design features of the advanced power reactors were verified and lots of the safety issues were also resolved.
Development of thermal hydraulic models for the reliable regulatory auditing code
Energy Technology Data Exchange (ETDEWEB)
Chung, B. D.; Song, C. H.; Lee, Y. J.; Kwon, T. S. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
2003-04-15
The objective of this project is to develop thermal hydraulic models for use in improving the reliability of the regulatory auditing codes. The current year fall under the first step of the 3 year project, and the main researches were focused on identifying the candidate thermal hydraulic models for improvement and to develop prototypical model development. During the current year, the verification calculations submitted for the APR 1400 design certification have been reviewed, the experimental data from the MIDAS DVI experiment facility in KAERI have been analyzed and evaluated, candidate thermal hydraulic models for improvement have been identified, prototypical models for the improved thermal hydraulic models have been developed, items for experiment in connection with the model development have been identified, and preliminary design of the experiment has been carried out.
Pen Branch Delta and Savannah River Swamp Hydraulic Model
Energy Technology Data Exchange (ETDEWEB)
Chen, K.F.
1999-05-13
The proposed Savannah River Site (SRS) Wetlands Restoration Project area is located in Barnwell County, South Carolina on the southwestern boundary of the SRS Reservation. The swamp covers about 40.5 km2 and is bounded to the west and south by the Savannah River and to the north and east by low bluffs at the edge of the Savannah River floodplain. Water levels within the swamp are determined by stage along the Savannah River, local drainage, groundwater seepage, and inflows from four tributaries, Beaver Dam Creek, Fourmile Branch, Pen Branch, and Steel Creek. Historic discharges of heated process water into these tributaries scoured the streambed, created deltas in the adjacent wetland, and killed native vegetation in the vicinity of the delta deposits. Future releases from these tributaries will be substantially smaller and closer to ambient temperatures. One component of the proposed restoration project will be to reestablish indigenous wetland vegetation on the Pen Branch delta that covers about 1.0 km2. Long-term predictions of water levels within the swamp are required to determine the characteristics of suitable plants. The objective of the study was to predict water levels at various locations within the proposed SRS Wetlands Restoration Project area for a range of Savannah River flows and regulated releases from Pen Branch. TABS-MD, a United States Army Corps of Engineer developed two-dimensional finite element open channel hydraulic computer code, was used to model the SRS swamp area for various flow conditions.
On-Line Core Thermal-Hydraulic Model Improvement
Energy Technology Data Exchange (ETDEWEB)
In, Wang Kee; Chun, Tae Hyun; Oh, Dong Seok; Shin, Chang Hwan; Hwang, Dae Hyun; Seo, Kyung Won
2007-02-15
The objective of this project is to implement a fast-running 4-channel based code CETOP-D in an advanced reactor core protection calculator system(RCOPS). The part required for the on-line calculation of DNBR were extracted from the source of the CETOP-D code based on analysis of the CETOP-D code. The CETOP-D code was revised to maintain the input and output variables which are the same as in CPC DNBR module. Since the DNBR module performs a complex calculation, it is divided into sub-modules per major calculation step. The functional design requirements for the DNBR module is documented and the values of the database(DB) constants were decided. This project also developed a Fortran module(BEST) of the RCOPS Fortran Simulator and a computer code RCOPS-SDNBR to independently calculate DNBR. A test was also conducted to verify the functional design and DB of thermal-hydraulic model which is necessary to calculate the DNBR on-line in RCOPS. The DNBR margin is expected to increase by 2%-3% once the CETOP-D code is used to calculate the RCOPS DNBR. It should be noted that the final DNBR margin improvement could be determined in the future based on overall uncertainty analysis of the RCOPS.
Evaluation of Fish Passage at Whitewater Parks Using 2D and 3D Hydraulic Modeling
Hardee, T.; Nelson, P. A.; Kondratieff, M.; Bledsoe, B. P.
2016-12-01
In-stream whitewater parks (WWPs) are increasingly popular recreational amenities that typically create waves by constricting flow through a chute to increase velocities and form a hydraulic jump. However, the hydraulic conditions these structures create can limit longitudinal habitat connectivity and potentially inhibit upstream fish migration, especially of native fishes. An improved understanding of the fundamental hydraulic processes and potential environmental effects of whitewater parks is needed to inform management decisions about Recreational In-Channel Diversions (RICDs). Here, we use hydraulic models to compute a continuous and spatially explicit description of velocity and depth along potential fish swimming paths in the flow field, and the ensemble of potential paths are compared to fish swimming performance data to predict fish passage via logistic regression analysis. While 3d models have been shown to accurately predict trout movement through WWP structures, 2d methods can provide a more cost-effective and manager-friendly approach to assessing the effects of similar hydraulic structures on fish passage when 3d analysis in not feasible. Here, we use 2d models to examine the hydraulics in several WWP structures on the North Fork of the St. Vrain River at Lyons, Colorado, and we compare these model results to fish passage predictions from a 3d model. Our analysis establishes a foundation for a practical, transferable and physically-rigorous 2d modeling approach for mechanistically evaluating the effects of hydraulic structures on fish passage.
Comparison between InfoWorks hydraulic results and a physical model of an urban drainage system.
Rubinato, Matteo; Shucksmith, James; Saul, Adrian J; Shepherd, Will
2013-01-01
Urban drainage systems are frequently analysed using hydraulic modelling software packages such as InfoWorks CS or MIKE-Urban. The use of such modelling tools allows the evaluation of sewer capacity and the likelihood and impact of pluvial flood events. Models can also be used to plan major investments such as increasing storage capacity or the implementation of sustainable urban drainage systems. In spite of their widespread use, when applied to flooding the results of hydraulic models are rarely compared with field or laboratory (i.e. physical modelling) data. This is largely due to the time and expense required to collect reliable empirical data sets. This paper describes a laboratory facility which will enable an urban flood model to be verified and generic approaches to be built. Results are presented from the first phase of testing, which compares the sub-surface hydraulic performance of a physical scale model of a sewer network in Yorkshire, UK, with downscaled results from a calibrated 1D InfoWorks hydraulic model of the site. A variety of real rainfall events measured in the catchment over a period of 15 months (April 2008-June 2009) have been both hydraulically modelled and reproduced in the physical model. In most cases a comparison of flow hydrographs generated in both hydraulic and physical models shows good agreement in terms of velocities which pass through the system.
Hydraulic fracturing model based on the discrete fracture model and the generalized J integral
Liu, Z. Q.; Liu, Z. F.; Wang, X. H.; Zeng, B.
2016-08-01
The hydraulic fracturing technique is an effective stimulation for low permeability reservoirs. In fracturing models, one key point is to accurately calculate the flux across the fracture surface and the stress intensity factor. To achieve high precision, the discrete fracture model is recommended to calculate the flux. Using the generalized J integral, the present work obtains an accurate simulation of the stress intensity factor. Based on the above factors, an alternative hydraulic fracturing model is presented. Examples are included to demonstrate the reliability of the proposed model and its ability to model the fracture propagation. Subsequently, the model is used to describe the relationship between the geometry of the fracture and the fracturing equipment parameters. The numerical results indicate that the working pressure and the pump power will significantly influence the fracturing process.
Fluid-solid interaction model for hydraulic reciprocating O-ring seals
Liao, Chuanjun; Huang, Weifeng; Wang, Yuming; Suo, Shuangfu; Liu, Ying
2013-01-01
Elastohydrodynamic lubrication characteristics of hydraulic reciprocating seals have significant effects on sealing and tribology performances of hydraulic actuators, especially in high parameter hydraulic systems. Only elastic deformations of hydraulic reciprocating seals were discussed, and hydrodynamic effects were neglected in many studies. The physical process of the fluid-solid interaction effect did not be clearly presented in the existing fluid-solid interaction models for hydraulic reciprocating O-ring seals, and few of these models had been simultaneously validated through experiments. By exploring the physical process of the fluid-solid interaction effect of the hydraulic reciprocating O-ring seal, a numerical fluid-solid interaction model consisting of fluid lubrication, contact mechanics, asperity contact and elastic deformation analyses is constructed with an iterative procedure. With the SRV friction and wear tester, the experiments are performed to investigate the elastohydrodynamic lubrication characteristics of the O-ring seal. The regularity of the friction coefficient varying with the speed of reciprocating motion is obtained in the mixed lubrication condition. The experimental result is used to validate the fluid-solid interaction model. Based on the model, The elastohydrodynamic lubrication characteristics of the hydraulic reciprocating O-ring seal are presented respectively in the dry friction, mixed lubrication and full film lubrication conditions, including of the contact pressure, film thickness, friction coefficient, liquid film pressure and viscous shear stress in the sealing zone. The proposed numerical fluid-solid interaction model can be effectively used to analyze the operation characteristics of the hydraulic reciprocating O-ring seal, and can also be widely used to study other hydraulic reciprocating seals.
Implementation and implications of macrophyte reconfiguration in hydraulic river modeling
Verschoren, Veerle; Schoelynck, Jonas; Buis, Kerst; Meire, Dieter; Bal, Kris; Meire, Patrick; Temmerman, Stijn
2014-05-01
In lowland rivers, abundant macrophyte growth can often be observed. The aquatic vegetation has an impact on the flow by creating friction which results in increased water levels and decreased flow velocities. At the same time submerged macrophytes are susceptible to hydrodynamic forces of the water. Their morphology is therefore often flexible and streamlined so that it enables reconfiguration (i.e. bending of macrophytes with water flow) and decreases potential damage at high flow velocities. Knowledge of these mutual interactions is crucial in order to model water flow in vegetated rivers. A correct estimation of flow velocity and water height is indispensable for the calculation of hydraulic, ecological and geomorphological parameters. The total resistance to water flow in a river can be described by a Manning coefficient. This value is influenced by river characteristics as well as by the presence of macrophytes. In this study a simple method is developed to quantify the resistance created by macrophytes after reconfiguration of their canopy. In order to achieve this we derive model formulations and plant parameters for three different macrophyte species and compare model simulation with measured flow velocity data for two case studies. Furthermore, the effect of macrophyte reconfiguration is investigated by modeling the same case studies with and without the implementation of macrophyte reconfiguration. It was found that the local resistance created by the vegetation was overestimated when reconfiguration was not considered. This resulted in an overestimation of stream velocity adjacent to the vegetation and an underestimation of the stream velocity within and behind the vegetation. Another effect was a higher water level gradient and consequently a higher Manning coefficient in the scenario without reconfiguration compared to the scenario with reconfiguration. Reconfiguration had also an influence on ecological and geomorphological parameters. It was found
Recent Developments in Multiscale and Multiphase Modelling of the Hydraulic Fracturing Process
Directory of Open Access Journals (Sweden)
Yong Sheng
2015-01-01
Full Text Available Recently hydraulic fracturing of rocks has received much attention not only for its economic importance but also for its potential environmental impact. The hydraulically fracturing technique has been widely used in the oil (EOR and gas (EGR industries, especially in the USA, to extract more oil/gas through the deep rock formations. Also there have been increasing interests in utilising the hydraulic fracturing technique in geological storage of CO2 in recent years. In all cases, the design and implementation of the hydraulic fracturing process play a central role, highlighting the significance of research and development of this technique. However, the uncertainty behind the fracking mechanism has triggered public debates regarding the possible effect of this technique on human health and the environment. This has presented new challenges in the study of the hydraulic fracturing process. This paper describes the hydraulic fracturing mechanism and provides an overview of past and recent developments of the research performed towards better understandings of the hydraulic fracturing and its potential impacts, with particular emphasis on the development of modelling techniques and their implementation on the hydraulic fracturing.
Theoretical Modeling of Internal Hydraulic Jump in Density Currents
Firoozabadi, Bahar; Aryanfar, Asghar; Afshin, Hossein
2013-01-01
In this paper, we propose an analytical framework for internal hydraulic jumps. Density jumps or internal hydraulic jumps occur when a supper critical flow of water discharges into a stagnant layer of water with slightly different density. The approach used here is control volume method which is also used to analyze ordinary hydraulic jumps. The important difference here is that entrainment is taken into account. Using conservation equations with the aid of some simplifying assumptions we come to an equation that gives jump downstream height as function of jump upstream characteristics and the entrainment. To determine the magnitude of downstream height we use an experimental equation for calculating the entrainment. Finally we verify our framework by comparing the height that we gain from the derived equation with some experimental data.
Owen, Gareth; Wilkinson, Mark; Nicholson, Alex; Quinn, Paul; O'Donnell, Greg
2015-04-01
There is an increase in the use of Natural Flood Management (NFM) schemes to tackle excessive runoff in rural catchments, but direct evidence of their functioning during extreme events is often lacking. With the availability of low cost sensors, a dense nested monitoring network can be established to provide near continuous optical and physical observations of hydrological processes. This paper will discuss findings for a number of catchments in the North of England where land use management and NFM have been implemented for flood risk reduction; and show how these observations have been used to inform both a hydraulic and a rainfall-runoff model. The value of observations in understanding how measures function is of fundamental importance and is becoming increasingly viable and affordable. Open source electronic platforms such as Arduino and Raspberry Pi are being used with cheap sensors to perform these tasks. For example, a level gauge has been developed for approximately €110 and cameras capable of capturing still or moving pictures are available for approximately €120; these are being used to better understand the behaviour of NFM features such as ponds and woody debris. There is potential for networks of these instruments to be configured and data collected through Wi-Fi or other wireless networks. The potential to expand informative networks of data that can constrain models is now possible. The functioning of small scale runoff attenuation features, such as offline ponds, has been demonstrated at the local scale. Specifically, through the measurement of both instream and in-pond water levels, it has been possible to calculate the impact of storing/attenuating flood flows on the adjacent river flow. This information has been encapsulated in a hydraulic model that allows the extrapolation of impacts to the larger catchment scale, contributing to understanding of the scalability of such features. Using a dense network of level gauges located along the main
Using the Casson model in a rheological and hydraulic evaluation of wash fluids
Energy Technology Data Exchange (ETDEWEB)
Dorman, J.
1984-01-01
The Ostwald de Waale or Robertson Stiff rheological models or their variants with corrections for temperature are convenient for determining the hydraulic drilling parameters. A series of examples is cited.
Locations of hydraulic-head observations (HOBS) for the Central Valley Hydrologic Model (CVHM)
U.S. Geological Survey, Department of the Interior — This digital dataset defines the well locations for hydraulic-head observations used in the calibration of the transient hydrologic model of the Central Valley flow...
Hydraulic modelling of drinking water treatment plant operations
Worm, G.I.M.; Mesman, G.A.M.; Van Schagen, K.M.; Borger, K.J.; Rietveld, L.C.
2009-01-01
The flow through a unit of a drinking water treatment plant is one of the most important parameters in terms of a unit's effectiveness. In the present paper, a new EPAnet library is presented with the typical hydraulic elements for drinking water treatment processes well abstraction, rapid sand filt
Establishment of digital model for dynamic simulation analysis on hydraulic impact perforator
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
Hydraulic impact perforator is powerful tools for trenchless project. It has advantages in cabinet structure, low cost, long life and easy protected. Compared with pneumatic DTH, the hydraulic impact spear worked under high pressure and using uncompressible fluid thusgreater impact energy and higher efficiency can be supported. The authors founded the dynamic simulation model of HDI-146 hydraulic impact spear. The project for solving the differential equation was suggested also. By means of virtual machine technology, the dynamic mechanism of HDI-146 can be explored and tutoring us to optimize the structural parameters can be made.
EFFECTIVE APPLICATIO N OF LIDAR DATA IN T WO - DIMENSIONAL HYDRAULIC MODELLING
Directory of Open Access Journals (Sweden)
Bakuła Krzysztof
2014-12-01
Full Text Available This paper presents aspects of ALS data usage in two - dimensional hydraulic modelling including generation of high - precision digital terrain models, t heir effective processing which is a compromise between the resolution and the accuracy of the processed data, as well as information about the roughness of the land cover providing information that could compete with information from topographic databases and orthophotomaps. Still evolving ALS technology makes it possible to collect the data with constantly increasing spatial resolution that guarantees correct representation of the terrain shape and height. It also provides a reliable description of the la nd cover. However, the size of generated files may cause roblems in their effective usage in the 2D hydraulic modeling where Saint - Venant’s equations are implemented. High - resolution elevation models make it impossible or prolong the duration of the calcu lations for large areas in complex algorithms defining a model of the water movement, which is directly related to the cost of the hydraulic analysis. As far as an effective usage of voluminous datasets is concerned, the data reduction is recommended. Suc h a process should reduce the size of the data files, maintain their accuracy and keep the appropriate structure to allow their further application in the hydraulic modelling. An application of only a few percent of unprocessed datasets, selected with the use of specified filtering algorithms and spatial analysis tools, can give the same result of the hydraulic modeling obtained in a significantly shorter time than the result of the comparable operation on unprocessed datasets. Such an approach, however, is not commonly used, which means the most reliable hydraulic models are applied only in small areas in the largest cities. Another application of ALS data is its potential usage in digital roughness model creation for 2D hydraulic models. There are many po ssibilities of roughness
Control method and system for hydraulic machines employing a dynamic joint motion model
Danko, George
2011-11-22
A control method and system for controlling a hydraulically actuated mechanical arm to perform a task, the mechanical arm optionally being a hydraulically actuated excavator arm. The method can include determining a dynamic model of the motion of the hydraulic arm for each hydraulic arm link by relating the input signal vector for each respective link to the output signal vector for the same link. Also the method can include determining an error signal for each link as the weighted sum of the differences between a measured position and a reference position and between the time derivatives of the measured position and the time derivatives of the reference position for each respective link. The weights used in the determination of the error signal can be determined from the constant coefficients of the dynamic model. The error signal can be applied in a closed negative feedback control loop to diminish or eliminate the error signal for each respective link.
Numerical simulation of the two-phase flows in a hydraulic coupling by solving VOF model
Luo, Y.; Zuo, Z. G.; Liu, S. H.; Fan, H. G.; Zhuge, W. L.
2013-12-01
The flow in a partially filled hydraulic coupling is essentially a gas-liquid two-phase flow, in which the distribution of two phases has significant influence on its characteristics. The interfaces between the air and the liquid, and the circulating flows inside the hydraulic coupling can be simulated by solving the VOF two-phase model. In this paper, PISO algorithm and RNG k-ɛ turbulence model were employed to simulate the phase distribution and the flow field in a hydraulic coupling with 80% liquid fill. The results indicate that the flow forms a circulating movement on the torus section with decreasing speed ratio. In the pump impeller, the air phase mostly accumulates on the suction side of the blades, while liquid on the pressure side; in turbine runner, air locates in the middle of the flow passage. Flow separations appear near the blades and the enclosing boundaries of the hydraulic coupling.
Discussion on Pipe Model through Hydraulic Architecture of Pinus tabulaeformis Seedling
Institute of Scientific and Technical Information of China (English)
ZHAIHongbo; LIJiyue; NIELishui
2004-01-01
In the paper, the hydraulic architecture parameters of Pinus tabulaeformis seedlings (4 years old) were measured by improved flushing method under normal water condition in the green house and the basic theory of hydraulic architecture is used to discuss the rationality of the pipe model. The results of the experiment and simulation show that the differences of hydraulic conductivity, specific conductivity and leaf specific conductivity is great in different stems and branches of Pinus tabulaeformis seedlings. The hydraulic conductivity of non-constriction area is higher than that of constriction area. The devotion of functional xylem of stem to unit leaf growth is not a constant, namely, the Huber value is diverse. Even though the pipe model has been accepted in some areas, its precondition is not perfect, and it is helpless in correctly understanding the essence of water transport in seedlings from the prospective of water physiology.
Institute of Scientific and Technical Information of China (English)
FAN Liwei; Hai Reti; WANG Wenxing; LU Zexiang; YANG Zhiming
2008-01-01
A subsurface flow wetland (SSFW) was simulated using a commercial computational fluid dynamic (CFD) code. The constructed media was simulated using porous media and the liquid resident time distribution (RTD) in the SSFW was obtained using the particle trajectory model. The effect of wetland configuration and operating conditions on the hydraulic performance of the SSFW were investigated. The results indicated that the hydraulic performance of the SSFW was predominantly affected by the wetland configuration. The hydraulic efficiency of the SSFW with an inlet at the middle edge of the upper media was 0.584 and the best among the SSFWs with an inlet at the top, the middle, and the bottom edge of the upper media. The constructed media affected the hydraulic performance by the ratio (K) of the upper and lower media resistance. The selection of appropriate media resistance in the protection layer can improve the hydraulic efficiency. When the viscous resistance coefficient of the media in the protection layer changed from 2.315×105 to 1.200×108, the hydraulic efficiency of the SSFW increased from 0.301 to 0.751. However, the effect of operating conditions on the hydraulic efficiency of the SSFW was slight.
U.S. Geological Survey, Department of the Interior — This digital dataset defines the model-grid and hydraulic-property data arrays of the Multiplier (MULT) Package used in the transient hydrologic model of the Central...
Dependence of Segregation Potential on the Thermal and Hydraulic Conditions Predicted by Model M1
1994-04-01
of Segregation Potential on the Thermal and Hydraulic Conditions Predicted by Model M, Yoshisuke Nakano April 1994 Rom edfor OFFICE OF THE CHIEF OF...function where i = 1, 2, 3 final ice lens k thermal conductivity of a frozen fringe 7* temperature at n, at the phase equilib- k ...hermalcoductivityoftheunfrozenpart rium of water of the soil T; average temperature gradient in R1 k , thermal conductivity of an ice layer U defined by eq 29a K0 hydraulic
How Plant Hydraulics can Improve the Modeling of Plant and Ecosystem Responses to Environment
Sperry, J.; Anderegg, W.; Mackay, D. S.; Venturas, M.
2016-12-01
Stomatal regulation is an important, yet problematic component in modeling plant-environment interactions. The problem is that stomata respond to so many environmental cues via complex and uncertain mechanisms. But the assumed end result of regulation is conceptually simple: an optimization of CO2 for H2O exchange in response to changing conditions. Stomata open when photosynthetic opportunity is high and water is cheap. They close if photosynthetic opportunity is low or water is very expensive. Photosynthetic opportunity is relatively easy to model. The cost of water loss is also easy to model if it is assumed to rise with greater proximity to hydraulic failure and desiccation. Unsaturated hydraulic conductivity curves of soil- and plant are used to estimate proximity to failure. At any given instant, a model can calculate opportunity and cost curves associated with greater stomatal opening. If stomata regulate to maximize the instantaneous difference between photosynthetic gain and hydraulic cost, then a model can predict the trajectory of stomatal responses to changes in environment across time. Results of this optimization routine extend the utility of hydraulic predecessor models, and are consistent with widely used empirical models across a wide range of vapor pressure deficit and ambient CO2 concentrations for wet soil. The advantage of the optimization approach is the absence of empirical coefficients, applicability to dry as well as wet soil, and prediction of plant hydraulic status along with gas exchange. The optimization algorithm is a trait- and process-based approach that could improve next generation land surface models.
Modeling, Optimization, and Detailed Design of a Hydraulic Flywheel-Accumulator
Strohmaier, Kyle Glenn
Improving mobile energy storage technology is an important means of addressing concerns over fossil fuel scarcity and energy independence. Traditional hydraulic accumulator energy storage, though favorable in power density, durability, cost, and environmental impact, suffers from relatively low energy density and a pressure-dependent state of charge. The hydraulic flywheel-accumulator concept utilizes both the hydro-pneumatic and rotating kinetic energy domains by employing a rotating pressure vessel. This thesis provides an in-depth analysis of the hydraulic flywheel-accumulator concept and an assessment of the advantages it offers over traditional static accumulator energy storage. After specifying a practical architecture for the hydraulic flywheel-accumulator, this thesis addresses the complex fluid phenomena and control implications associated with multi-domain energy storage. To facilitate rapid selection of the hydraulic flywheel-accumulator dimensions, computationally inexpensive material stress models are developed for each component. A drive cycle simulation strategy is also developed to assess the dynamic performance of the device. The stress models and performance simulation are combined to form a toolset that facilitates computationally-efficient model-based design. The aforementioned toolset has been embedded into a multi-objective optimization algorithm that aims to minimize the mass of the hydraulic flywheel-accumulator system and to minimize the losses it incurs over the course of a drive cycle. Two optimizations have been performed - one with constraints that reflect a vehicle-scale application, and one with constraints that reflect a laboratory application. At both scales, the optimization results suggest that the hydraulic flywheel-accumulator offers at least an order of magnitude improvement over traditional static accumulator energy storage, while operating at efficiencies between 75% and 93%. A particular hydraulic flywheel-accumulator design
Hsiao, Kai-Wen; Hsu, Yu-Chao; Jan, Chyan-Deng; Su, Yu-Wen
2016-04-01
The inclined rectangular chute construction is a common structure used in hydraulic engineering for typical reasons such as the increase of bottom slope, the transition from side channel intakes to tunnel spillways, the drainage construction, and the reduction of chute width due to bridges, flood diversion structures or irrigation systems. The converging vertical sidewalls of a chute contraction deflect the supercritical flow to form hydraulic shock waves. Hydraulic shock waves have narrow and locally extreme wavy surfaces, which commonly results in the requirement of higher height of sidewalls. Therefore, predicting the possible height and position of maximum hydraulic shock wave are necessary to design the required height of sidewalls to prevent flow overtopping. In this study, we used a three-dimensional computation fluid dynamics model (i.e., FLOW-3D) to simulate the characteristics of hydraulic shock waves in an inclined chute contraction. For this purpose, the parameters of simulated hydraulic shock wave, such as the shock angle, maximum shock wave height and maximum shock wave position in various conditions are compared with those calculated by the empirical relations obtained from literatures. We showed that the simulated results are extremely close to the experimental results. The numerical results validated the applicability of these empirical relations and extend their applicability to higher approach Froude numbers from 3.51 to 7.27. Furthermore, we also applied the Yuan-Shan-Tsu flood diversion channel under 200-year peak flow condition to FLOW-3D model to simulate the hydraulic shock waves and validate the effect of the installation of a diversion pier in the channel on promoting the stability of flow fluid. The results revealed that a diversion pier installed in the Yuan-Shan-Tsu flood diversion channel is helpful for improving the stability of flow field. In summary, this study demonstrates that FLOW-3D model can be used to simulate the
HYDROLOGIC AND HYDRAULIC MODELLING INTEGRATED WITH GIS: A STUDY OF THE ACARAÚ RIVER BASIN – CE
Directory of Open Access Journals (Sweden)
Samuellson Lopes Cabral
2014-01-01
Full Text Available The paper presents a case study integrating hydrologic models, hydraulic models and a geographic information system (GIS to delineate flooded areas in the medium-sized Acaraú River Basin in Ceará State, Brazil. The computational tools used were HEC-HMS for hydrologic modelling, HEC-RAS for hydraulic modelling and HEC-GeoRAS for the GIS. The results showed that a substantial portion of the riverine populations of the cities of Sobral, Santana do Acaraú and Groairas were affected by floods. Overall, the flood model satisfactorily represents the affected areas and shows the locations with the greatest flooding.
Modelling of an hydraulic excavator using simplified refined instrumental variable(SRIV)algorithm
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Instead of establishing mathematical hydraulic system models from physical laws usually done with the problems of complex modelling processes,low reliability and practicality caused by large uncertainties,a novel modelling method for a highly nonlinear system of a hydraulic excavator is presented.Based on the data collected in the excavator's arms driving experiments,a data-based excavator dynamic model using Simplified Refined Instrumental Variable(SRIV)identification and estimation algorithms is established.The validity of the proposed data-based model is indirectly demonstrated by the performance of computer simulation and the real machine motion control experiments.
Iden, Sascha; Peters, Andre; Durner, Wolfgang
2017-04-01
Soil hydraulic properties are required to solve the Richards equation, the most widely applied model for variably-saturated flow. While the experimental determination of the water retention curve does not pose significant challenges, the measurement of unsaturated hydraulic conductivity is time consuming and costly. The prediction of the unsaturated hydraulic conductivity curve from the soil water retention curve by pore-bundle models is a cost-effective and widely applied technique. A well-known problem of conductivity prediction for retention functions with wide pore-size distributions is the sharp drop in conductivity close to water saturation. This problematic behavior is well known for the van Genuchten model if the shape parameter n assumes values smaller than about 1.3. So far, the workaround for this artefact has been to introduce an explicit air-entry value into the capillary saturation function. However, this correction leads to a retention function which is not continuously differentiable and thus a discontinuous water capacity function. We present an improved parametrization of the hydraulic properties which uses the original capillary saturation function and introduces a maximum pore radius only in the pore-bundle model. Closed-form equations for the hydraulic conductivity function were derived for the unimodal and multimodal retention functions of van Genuchten and have been tested by sensitivity analysis and applied in curve fitting and inverse modeling of multistep outflow experiments. The resulting hydraulic conductivity function is smooth, increases monotonically close to saturation, and eliminates the sharp drop in conductivity close to saturation. Furthermore, the new model retains the smoothness and continuous differentiability of the water retention curve. We conclude that the resulting soil hydraulic functions are physically more reasonable than the ones predicted by previous approaches, and are thus ideally suited for numerical simulations
Evaluation of Regression and Neuro_Fuzzy Models in Estimating Saturated Hydraulic Conductivity
Directory of Open Access Journals (Sweden)
J. Behmanesh
2015-06-01
Full Text Available Study of soil hydraulic properties such as saturated and unsaturated hydraulic conductivity is required in the environmental investigations. Despite numerous research, measuring saturated hydraulic conductivity using by direct methods are still costly, time consuming and professional. Therefore estimating saturated hydraulic conductivity using rapid and low cost methods such as pedo-transfer functions with acceptable accuracy was developed. The purpose of this research was to compare and evaluate 11 pedo-transfer functions and Adaptive Neuro-Fuzzy Inference System (ANFIS to estimate saturated hydraulic conductivity of soil. In this direct, saturated hydraulic conductivity and physical properties in 40 points of Urmia were calculated. The soil excavated was used in the lab to determine its easily accessible parameters. The results showed that among existing models, Aimrun et al model had the best estimation for soil saturated hydraulic conductivity. For mentioned model, the Root Mean Square Error and Mean Absolute Error parameters were 0.174 and 0.028 m/day respectively. The results of the present research, emphasises the importance of effective porosity application as an important accessible parameter in accuracy of pedo-transfer functions. sand and silt percent, bulk density and soil particle density were selected to apply in 561 ANFIS models. In training phase of best ANFIS model, the R2 and RMSE were calculated 1 and 1.2×10-7 respectively. These amounts in the test phase were 0.98 and 0.0006 respectively. Comparison of regression and ANFIS models showed that the ANFIS model had better results than regression functions. Also Nuro-Fuzzy Inference System had capability to estimatae with high accuracy in various soil textures.
LVP modeling and dynamic characteristics prediction of a hydraulic power unit in deep-sea
Cao, Xue-peng; Ye, Min; Deng, Bin; Zhang, Cui-hong; Yu, Zu-ying
2013-03-01
A hydraulic power unit (HPU) is the driving "heart" of deep-sea working equipment. It is critical to predict its dynamic performances in deep-water before being immerged in the seawater, while the experimental tests by simulating deep-sea environment have many disadvantages, such as expensive cost, long test cycles, and difficult to achieve low-temperature simulation, which is only used as a supplementary means for confirmatory experiment. This paper proposes a novel theoretical approach based on the linear varying parameters (LVP) modeling to foresee the dynamic performances of the driving unit. Firstly, based on the varying environment features, dynamic expressions of the compressibility and viscosity of hydraulic oil are derived to reveal the fluid performances changing. Secondly, models of hydraulic system and electrical system are accomplished respectively through studying the control process and energy transfer, and then LVP models of the pressure and flow rate control is obtained through the electro-hydraulic models integration. Thirdly, dynamic characteristics of HPU are obtained by the model simulating within bounded closed sets of varying parameters. Finally, the developed HPU is tested in a deep-sea imitating hull, and the experimental results are well consistent with the theoretical analysis outcomes, which clearly declare that the LVP modeling is a rational way to foresee dynamic performances of HPU. The research approach and model analysis results can be applied to the predictions of working properties and product designs for other deep-sea hydraulic pump.
Rosenzweig, Ravid; Furman, Alex; Dosoretz, Carlos; Shavit, Uri
2014-07-01
Biofilm effects on water flow in unsaturated environments have largely been ignored in the past. However, intensive engineered systems that involve elevated organic loads such as wastewater irrigation, effluent recharge, and bioremediation processes make understanding how biofilms affect flow highly important. In the current work, we present a channel-network model that incorporates water flow, substrate transport, and biofilm dynamics to simulate the alteration of soil hydraulic properties, namely water retention and conductivity. The change in hydraulic properties due to biofilm growth is not trivial and depends highly on the spatial distribution of the biofilm development. Our results indicate that the substrate mass transfer coefficient across the water-biofilm interface dominates the spatiotemporal distribution of biofilm. High mass transfer coefficients lead to uncontrolled biofilm growth close to the substrate source, resulting in preferential clogging of the soil. Low mass transfer coefficients, on the other hand, lead to a more uniform biofilm distribution. The first scenario leads to a dramatic reduction of the hydraulic conductivity with almost no change in water retention, whereas the second scenario has a smaller effect on conductivity but a larger influence on retention. The current modeling approach identifies key factors that still need to be studied and opens the way for simulation and optimization of processes involving significant biological activity in unsaturated soils.
Modelling of Moving Coil Actuators in Fast Switching Valves Suitable for Digital Hydraulic Machines
DEFF Research Database (Denmark)
Nørgård, Christian; Roemer, Daniel Beck; Bech, Michael Møller
2015-01-01
The efficiency of digital hydraulic machines is strongly dependent on the valve switching time. Recently, fast switching have been achieved by using a direct electromagnetic moving coil actuator as the force producing element in fast switching hydraulic valves suitable for digital hydraulic...... machines. Mathematical models of the valve switching, targeted for design optimisation of the moving coil actuator, are developed. A detailed analytical model is derived and presented and its accuracy is evaluated against transient electromagnetic finite element simulations. The model includes...... an estimation of the eddy currents generated in the actuator yoke upon current rise, as they may have significant influence on the coil current response. The analytical model facilitates fast simulation of the transient actuator response opposed to the transient electro-magnetic finite element model which...
Modelling of liquid flow after a hydraulic jump on a rotating disk prior to centrifugal atomization
Zhao, Y. Y.; Dowson, A. L.; Jacobs, M. H.
2000-01-01
This paper describes a simplified numerical model which is used to calculate the height distribution, and the radial and tangential velocities of a liquid on a rotating disk after a hydraulic jump and prior to centrifugal atomization. The results obtained from this numerical model are compared with predictions made using previously derived `hydraulic jump' and `analytical' models. Calculations, in conjunction with experimental measurements relating to the trajectory of liquid flow on the atomizing disk, have shown that the numerical model can not only give a reasonable prediction of the hydraulic jump location, but also yields more accurate information regarding the variations in liquid height, and radial and tangential velocities. The model is ideally suited for engineering applications.
Simulation of Hydraulic and Natural Fracture Interaction Using a Coupled DFN-DEM Model
Energy Technology Data Exchange (ETDEWEB)
J. Zhou; H. Huang; M. Deo
2016-03-01
The presence of natural fractures will usually result in a complex fracture network due to the interactions between hydraulic and natural fracture. The reactivation of natural fractures can generally provide additional flow paths from formation to wellbore which play a crucial role in improving the hydrocarbon recovery in these ultra-low permeability reservoir. Thus, accurate description of the geometry of discrete fractures and bedding is highly desired for accurate flow and production predictions. Compared to conventional continuum models that implicitly represent the discrete feature, Discrete Fracture Network (DFN) models could realistically model the connectivity of discontinuities at both reservoir scale and well scale. In this work, a new hybrid numerical model that couples Discrete Fracture Network (DFN) and Dual-Lattice Discrete Element Method (DL-DEM) is proposed to investigate the interaction between hydraulic fracture and natural fractures. Based on the proposed model, the effects of natural fracture orientation, density and injection properties on hydraulic-natural fractures interaction are investigated.
Numerical modeling of the near-field hydraulics of water wells.
Houben, Georg J; Hauschild, Sarah
2011-01-01
Numerical flow models can be a useful tool for dimensioning water wells and to investigate the hydraulics in their near-field. Fully laminar flow can be assumed for all models calculated up to the screen. Therefore models can be used to predict--at least qualitatively, neglecting turbulent losses inside the well--the spatial distribution of inflow into the well and the overall hydraulic performance of different combinations of aquifer parameters and technical installations. Models for both horizontal (plan view) and vertical flow (cross section) to wells were calculated for a variety of setups. For the latter, this included variations of hydraulic conductivity of the screen, pump position, and aquifer heterogeneity. Models of suction flow control devices showed that they indeed can homogenize inflow, albeit at the cost of elevated entrance losses.
Hydraulic modeling for lahar hazards at cascades volcanoes
Costa, J.E.
1997-01-01
The National Weather Service flood routing model DAMBRK is able to closely replicate field-documented stages of historic and prehistoric lahars from Mt. Rainier, Washington, and Mt. Hood, Oregon. Modeled time-of-travel of flow waves are generally consistent with documented lahar travel-times from other volcanoes around the world. The model adequately replicates a range of lahars and debris flows, including the 230 million km3 Electron lahar from Mt. Rainier, as well as a 10 m3 debris flow generated in a large outdoor experimental flume. The model is used to simulate a hypothetical lahar with a volume of 50 million m3 down the East Fork Hood River from Mt. Hood, Oregon. Although a flow such as this is thought to be possible in the Hood River valley, no field evidence exists on which to base a hazards assessment. DAMBRK seems likely to be usable in many volcanic settings to estimate discharge, velocity, and inundation areas of lahars when input hydrographs and energy-loss coefficients can be reasonably estimated.
Thermo-hydraulic modeling of flow in flare systems
Meindinyo, Remi-Erempagamo T.
2012-01-01
Flare systems play a major role in the safety of Oil and Gas installations by serving as outlets for emergency pressure relief in case of process upsets. Accurate and reliable estimation of system thermo-hydraulic parameters, especially system back-pressure is critical to the integrity of a flare design. FlareNet (Aspen Flare System Analyzer Version 7) is a steady state simulation tool tailored for flare system design and has found common use today. But design based on steady state modelin...
Application of Fuzzy Clustering in Modeling of a Water Hydraulics System
DEFF Research Database (Denmark)
Zhou, Jianjun; Kroszynski, Uri
2000-01-01
This article presents a case study of applying fuzzy modeling techniques for a water hydraulics system. The obtained model is intended to provide a basis for model-based control of the system. Fuzzy clustering is used for classifying measured input-output data points into partitions. The fuzzy mo...
Thermal-hydraulic modeling needs for passive reactors
Energy Technology Data Exchange (ETDEWEB)
Kelly, J.M. [Nuclear Regulatory Commission, Washington, DC (United States)
1997-07-01
The U.S. Nuclear Regulatory Commission has received an application for design certification from the Westinghouse Electric Corporation for an Advanced Light Water Reactor design known as the AP600. As part of the design certification process, the USNRC uses its thermal-hydraulic system analysis codes to independently audit the vendor calculations. The focus of this effort has been the small break LOCA transients that rely upon the passive safety features of the design to depressurize the primary system sufficiently so that gravity driven injection can provide a stable source for long term cooling. Of course, large break LOCAs have also been considered, but as the involved phenomena do not appear to be appreciably different from those of current plants, they were not discussed in this paper. Although the SBLOCA scenario does not appear to threaten core coolability - indeed, heatup is not even expected to occur - there have been concerns as to the performance of the passive safety systems. For example, the passive systems drive flows with small heads, consequently requiring more precision in the analysis compared to active systems methods for passive plants as compared to current plants with active systems. For the analysis of SBLOCAs and operating transients, the USNRC uses the RELAP5 thermal-hydraulic system analysis code. To assure the applicability of RELAP5 to the analysis of these transients for the AP600 design, a four year long program of code development and assessment has been undertaken.
Iden, Sascha C.; Peters, Andre; Durner, Wolfgang
2015-11-01
The prediction of unsaturated hydraulic conductivity from the soil water retention curve by pore-bundle models is a cost-effective and widely applied technique. One problem for conductivity predictions from retention functions with continuous derivatives, i.e. continuous water capacity functions, is that the hydraulic conductivity curve exhibits a sharp drop close to water saturation if the pore-size distribution is wide. So far this artifact has been ignored or removed by introducing an explicit air-entry value into the capillary saturation function. However, this correction leads to a retention function which is not continuously differentiable. We present a new parameterization of the hydraulic properties which uses the original saturation function (e.g. of van Genuchten) and introduces a maximum pore radius only in the pore-bundle model. In contrast to models using an explicit air entry, the resulting conductivity function is smooth and increases monotonically close to saturation. The model concept can easily be applied to any combination of retention curve and pore-bundle model. We derive closed-form expressions for the unimodal and multimodal van Genuchten-Mualem models and apply the model concept to curve fitting and inverse modeling of a transient outflow experiment. Since the new model retains the smoothness and continuous differentiability of the retention model and eliminates the sharp drop in conductivity close to saturation, the resulting hydraulic functions are physically more reasonable and ideal for numerical simulations with the Richards equation or multiphase flow models.
Experimental System Identification and Black Box Modeling of Hydraulic Directional Control Valve
Directory of Open Access Journals (Sweden)
Sondre Sanden Tørdal
2015-10-01
Full Text Available Directional control valves play a large role in most hydraulic systems. When modeling the hydraulic systems, it is important that both the steady state and dynamic characteristics of the valves are modeled correctly to reproduce the dynamic characteristics of the entire system. In this paper, a proportional valve (Brevini HPV 41 is investigated to identify its dynamic and steady state characteristics. The steady state characteristics are identified by experimental flow curves. The dynamics are determined through frequency response analysis and identified using several transfer functions. The paper also presents a simulation model of the valve describing both steady state and dynamic characteristics. The simulation results are verified through several experiments.
Discrete fracture network modeling of hydraulic stimulation coupling flow and geomechanics
McClure, Mark
2013-01-01
Discrete Fracture Network Modeling of Hydraulic Stimulation describes the development and testing of a model that couples fluid-flow, deformation, friction weakening, and permeability evolution in large, complex two-dimensional discrete fracture networks. The model can be used to explore the behavior of hydraulic stimulation in settings where matrix permeability is low and preexisting fractures play an important role, such as Enhanced Geothermal Systems and gas shale. Used also to describe pure shear stimulation, mixed-mechanism stimulation, or pure opening-mode stimulation. A variety of nov
Energy Technology Data Exchange (ETDEWEB)
Charoenwongsa, S.; Kazemi, H.; Miskimins, J.; Fakcharoenphol [Colorado School of Mines, Golden, CO (United States)
2010-07-01
A fully coupled geomechanics flow model was used to assess how the changes in pore pressure and temperature influence rock stresses in tight gas reservoirs. The finite difference method was used to develop simulations for phases, components, and thermal stresses. A wave component was used to model the propagation of the strain displacement front as well as changes in stress with time. Fluid and heat flow volumes were modelled separately from rock formation properties. The influence of hydraulic fracturing on stress distributions surrounding the fracture was investigated as well as the effect of filter cake and filtrate. Results of the study showed that significant changes in shear stresses near hydraulic fractures occur as a result of hydraulic fracture face displacement perpendicular to the fracture face. While temperature effects also caused changes in stress distributions, changes in pore pressure did not significantly impact shear stresses as the filtrate did not travel very far into the reservoir. 17 refs., 17 figs.
Multiobjective Optimization Design of Double-Row Blades Hydraulic Retarder with Surrogate Model
Directory of Open Access Journals (Sweden)
Liu Chunbao
2015-02-01
Full Text Available For the design of double-row blades hydraulic retarder involves too many parameters, the solution process of the optimal parameter combination is characterized by the large calculation load, the long calculation time, and the high cost. In this paper, we proposed a multiobjective optimization method to obtain the optimal balanced solution between the braking torque and volume of double-row blades hydraulic retarder. Moreover, we established the surrogate model for objective function with radial basis function (RBF, thus avoiding the time-consuming three-dimensional modeling and fluid simulation. Then, nondominated sorting genetic algorithm-II (NSGA-II was adopted to obtain the optimal combination solution of design variables. Moreover, the comparison results of computational fluid dynamics (CFD values of the optimal combination parameters and original design parameters indicated that the multiobjective optimization method based on surrogate model was applicable for the design of double-row blades hydraulic retarder.
Development of a 3D Stream Network and Topography for Improved Large-Scale Hydraulic Modeling
Saksena, S.; Dey, S.; Merwade, V.
2016-12-01
Most digital elevation models (DEMs) used for hydraulic modeling do not include channel bed elevations. As a result, the DEMs are complimented with additional bathymetric data for accurate hydraulic simulations. Existing methods to acquire bathymetric information through field surveys or through conceptual models are limited to reach-scale applications. With an increasing focus on large scale hydraulic modeling of rivers, a framework to estimate and incorporate bathymetry for an entire stream network is needed. This study proposes an interpolation-based algorithm to estimate bathymetry for a stream network by modifying the reach-based empirical River Channel Morphology Model (RCMM). The effect of a 3D stream network that includes river bathymetry is then investigated by creating a 1D hydraulic model (HEC-RAS) and 2D hydrodynamic model (Integrated Channel and Pond Routing) for the Upper Wabash River Basin in Indiana, USA. Results show improved simulation of flood depths and storage in the floodplain. Similarly, the impact of river bathymetry incorporation is more significant in the 2D model as compared to the 1D model.
A Stochastic model for two-station hydraulics exhibiting transient impact
DEFF Research Database (Denmark)
Jacobsen, Judith L.; Madsen, Henrik; Harremoës, Poul
1997-01-01
The objective of the paper is to interpret data on water level variation in a river affected by overflow from a sewer system during rain. The simplest possible, hydraulic description is combined with stochastic methods for data analysis and model parameter estimation. This combination of determin......The objective of the paper is to interpret data on water level variation in a river affected by overflow from a sewer system during rain. The simplest possible, hydraulic description is combined with stochastic methods for data analysis and model parameter estimation. This combination...
Sakai, Masaru; Van Genuchten, Martinus Th; Alazba, A. A.; Setiawan, Budi Indra; Minasny, Budiman
2015-01-01
A soil hydraulic model that considers capillary hysteretic and adsorptive water retention as well as capillary and film conductivity covering the complete soil moisture range is presented. The model was obtained by incorporating the capillary hysteresis model of Parker and Lenhard into the hydraulic
Assimilating SAR-derived water level data into a hydraulic model: a case study
Directory of Open Access Journals (Sweden)
L. Giustarini
2011-02-01
Full Text Available Satellite-based active microwave sensors not only provide synoptic overviews of flooded areas, but also offer an effective way to estimate spatially distributed river water levels. If rapidly produced and processed, these data can be used for updating hydraulic models in near real-time. The usefulness of such approaches with real event data sets provided by currently existing sensors has yet to be demonstrated. In this case study, a Particle Filter-based assimilation scheme is used to integrate ERS-2 SAR and ENVISAT ASAR-derived water level data into a one-dimensional (1-D hydraulic model of the Alzette River. Two variants of the Particle Filter assimilation scheme are proposed with a global and local particle weighting procedure. The first option finds the best water stage line across all cross sections, while the second option finds the best solution at individual cross sections. The variant that is to be preferred depends on the level of confidence that is attributed to the observations or to the model. The results show that the Particle Filter-based assimilation of remote sensing-derived water elevation data provides a significant reduction to the model forecast uncertainty. Moreover, it is shown that the periodical updating of hydraulic models through the proposed assimilation scheme leads to an improvement of model predictions over several time steps. However, the performance of the assimilation depends on the skill of the hydraulic model and the quality of the observation data.
Gerke, Kirill; Khirevich, Siarhei; Sizonenko, Timofey; Karsanina, Marina; Umarova, Aminat; Korost, Dmitry; Matthai, Stephan; Mallants, Dirk
2016-04-01
To verify pore-scale modelling approach for determination of soil saturated hydraulic conductivity properties we scanned three cylindrical soil samples taken from A, Ah and B horizons using X-ray microtomography method. Resulting 3D soil images with resolutions of 15.25-20.96 μm were segmented into pores and solids and their maximum inscribed cube subvolumes were used as input data for three major pore-scale modelling methods to simulate saturated flow - lattice-Boltzmann method, finite-difference solution of the Stokes problem, and pore-network model. Provided that imaging resolution is high enough to capture the backbone of effective porosity and the main conducting pores all three methods resulted in simulated soil permeabilities close to experimental values for Ah and B samples. The resolution of A sample was not enough for an accurate modelling and we concluded that this soil requires multi-scale imaging to cover all relevant heterogeneities. We demonstrate that popular SWV method to choose segmentation threshold resulted in oversegmentation and order of magnitude higher permeability values. Careful manual thresholding combined with local segmentation algorithm provided much more accurate results. Detailed analysis of water retention curves showed that air-filled porosity at relevant pressure stages cannot be used for verification of the segmentation results. Representativity analysis by simulating flow in increasing soil volume up to 2.8 cm3 revealed no representative elementary volume (REV) within Ah sample and non-uniqueness of REV for B sample. The latter was explained by soil structure non-stationarity. We further speculate that structures soil horizons can exhibit no REV at all. We discuss numerous advantages of coupled imaging and pore-scale modelling approach and show how it can become a successor of the conventional soil coring method to parametrize large scale continuum models.
Real-time dynamic hydraulic model for water distribution networks: steady state modelling
CSIR Research Space (South Africa)
Osman, Mohammad S
2016-09-01
Full Text Available stream_source_info Osman2_2016.pdf.txt stream_content_type text/plain stream_size 17244 Content-Encoding UTF-8 stream_name Osman2_2016.pdf.txt Content-Type text/plain; charset=UTF-8 REAL-TIME DYNAMIC HYDRAULIC MODEL... of specially developed methods which have been published and hence are not further discussed. ∆PfP is the pressure loss due to pipe friction and determined from Darcy-Weisbach equation (5): 2000 ' 2 D LufPfP (5) 'f is the friction factor L...
Models for Unsaturated Hydraulic Conductivity Based on Truncated Lognormal Pore-size Distributions
Malama, Bwalya
2013-01-01
We develop a closed-form three-parameter model for unsaturated hydraulic conductivity associated with a three-parameter lognormal model of moisture retention, which is based on lognormal grainsize distribution. The derivation of the model is made possible by a slight modification to the theory of Mualem. We extend the three-parameter lognormal distribution to a four-parameter model that also truncates the pore size distribution at a minimum pore radius. We then develop the corresponding four-parameter model for moisture retention and the associated closed-form expression for unsaturated hydraulic conductivity. The four-parameter model is fitted to experimental data, similar to the models of Kosugi and van Genuchten. The proposed four-parameter model retains the physical basis of Kosugi's model, while improving fit to observed data especially when simultaneously fitting pressure-saturation and pressure-conductivity data.
Development of two-phase pipeline hydraulic analysis model based on Beggs-Brill correlation
Waluyo, Joko; Hermawan, Achilleus; Indarto
2016-06-01
The hydraulic analysis is an important stage in a reliable pipeline design. In the implementation, fluid distribution from a source to the sinks often occurs on parallel pipeline networks. The solution to the problem is complicated because of the iterative technique requirement. Regarding its solution effectiveness, there is a need for analysis related to the model and the solution method. This study aims to investigate pipeline hydraulic analysis on distributing of two-phase fluids flow. The model uses Beggs-Brill correlation to converse mass flow rates into pressure drops. In the solution technique, the Newton-Raphson iterative method is utilized. The iterative technique is solved using a computer program. The study is carried out using a certain pipeline network. The model is validated by comparing between Beggs-Brill towards Mukherjee-Brill correlation. The result reveals that the computer program enables solving of iterative calculation on the parallel pipeline hydraulic analysis. Convergence iteration is achieved by 50 iterations. The main results of the model are mass flow rate and pressure drop. The mass flow rate is obtained in the deviation up to 2.06%, between Beggs-Brill and Mukherjee-Brill correlation. On the other hand, the pressure gradient deviation is achieved on a higher deviation due to the different approach of the two correlations. The model can be further developed in the hydraulic pipeline analysis for two-phase flow.
Zemenkova, M. Yu; Shipovalov, A. N.; Zemenkov, Yu D.
2016-04-01
The main technological equipment of pipeline transport of hydrocarbons are hydraulic machines. During transportation of oil mainly used of centrifugal pumps, designed to work in the “pumping station-pipeline” system. Composition of a standard pumping station consists of several pumps, complex hydraulic piping. The authors have developed a set of models and algorithms for calculating system reliability of pumps. It is based on the theory of reliability. As an example, considered one of the estimation methods with the application of graph theory.
Modeling and control of a hydraulically actuated flexible-prismatic link robot
Energy Technology Data Exchange (ETDEWEB)
Love, L.; Kress, R.; Jansen, J.
1996-12-01
Most of the research related to flexible link manipulators to date has focused on single link, fixed length, single plane of vibration test beds. In addition, actuation has been predominantly based upon electromagnetic motors. Ironically, these elements are rarely found in the existing industrial long reach systems. This manuscript describes a new hydraulically actuated, long reach manipulator with a flexible prismatic link at Oak Ridge National Laboratory (ORNL). Focus is directed towards both modeling and control of hydraulic actuators as well as flexible links that have variable natural frequencies.
Directory of Open Access Journals (Sweden)
T. McCormack
2017-04-01
New hydrological insights for the region: Results suggest two primary pathways of northwards groundwater flow in the catchment, a fault which discharges offshore, and a ∼2 m diameter karst conduit running underneath the catchment lowlands against the prevailing geological dip. This conduit, whose existence was suspected but never confirmed, links a large ephemeral lake to the coast where it discharges intertidally. Hydraulic modelling indicates that the conduit network is a complex mixture of constrictions with multiple inlets and outlets. Two ephemeral lakes are shown to be hydraulically discontinuous, either drained separately or linked by a low pressure channel.
Thermal-hydraulic analysis of LTS cables for the DEMO TF coil using simplified models
Directory of Open Access Journals (Sweden)
Lewandowska Monika
2017-03-01
Full Text Available The conceptual design activities for the DEMOnstration reactor (DEMO – the prototype fusion power plant – are conducted in Europe by the EUROfusion Consortium. In 2015, three design concepts of the DEMO toroidal field (TF coil were proposed by Swiss Plasma Center (EPFL-SPC, PSI Villigen, Italian National Agency for New Technologies (ENEA Frascati, and Atomic Energy and Alternative Energies Commission (CEA Cadarache. The proposed conductor designs were subjected to complete mechanical, electromagnetic, and thermal-hydraulic analyses. The present study is focused on the thermal-hydraulic analysis of the candidate conductor designs using simplified models. It includes (a hydraulic analysis, (b heat removal analysis, and (c assessment of the maximum temperature and the maximum pressure in each conductor during quench. The performed analysis, aimed at verification whether the proposed design concepts fulfil the established acceptance criteria, provides the information for further improvements of the coil and conductors design.
Institute of Scientific and Technical Information of China (English)
Yue JIN; Yang LU; Jiahui GONG; Zhixiong LU; Wenming LI; Jungan WU
2015-01-01
An Electro-hydraulic loading system is designed based on a test-bed of tractor’s hydraulic steering by-wire. To simulate the steering resistance driving tractor in many kinds of soils and roads,the loading force is controlled to make proportional and continuous variable by an electro-hydraulic proportional relief valve. A steering resistance loading test-bed is built to test three kinds of steering resistance including constant,step and sine style. Tire lateral resistance is also tested under different steering conditions. The result shows that the electro-hydraulic loading system has high stability and following performance. Besides,the system’s steady state error is lower than 3. 1%,and it meets the test requirement of tractor’s hydraulic steering by-wire.
LVP Modeling and Dynamic Characteristics Prediction of A Hydraulic Power Unit in Deep-Sea
Institute of Scientific and Technical Information of China (English)
CAO Xue-peng; YE Min; DENG Bin; ZHANG Cui-hong; YU Zu-ying
2013-01-01
A hydraulic power unit (HPU) is the driving "heart" of deep-sea working equipment.It is critical to predict its dynamic performances in deep-water before being immerged in the seawater,while the experimental tests by simulating deep-sea environment have many disadvantages,such as expensive cost,long test cycles,and difficult to achieve low-temperature simulation,which is only used as a supplementary means for confirmatory experiment.This paper proposes a novel theoretical approach based on the linear varying parameters (LVP) modeling to foresee the dynamic performances of the driving unit.Firstly,based on the varying environment features,dynamic expressions of the compressibility and viscosity of hydraulic oil are derived to reveal the fluid performances changing.Secondly,models of hydraulic system and electrical system are accomplished respectively through studying the control process and energy transfer,and then LVP models of the pressure and flow rate control is obtained through the electro-hydraulic models integration.Thirdly,dynamic characteristics of HPU are obtained by the model simulating within bounded closed sets of varying parameters.Finally,the developed HPU is tested in a deep-sea imitating hull,and the experimental results are well consistent with the theoretical analysis outcomes,which clearly declare that the LVP modeling is a rational way to foresee dynamic performances of HPU.The research approach and model analysis results can be applied to the predictions of working properties and product designs for other deep-sea hydraulic pump.
Discrete modeling of hydraulic fracturing processes in a complex pre-existing fracture network
Kim, K.; Rutqvist, J.; Nakagawa, S.; Houseworth, J. E.; Birkholzer, J. T.
2015-12-01
Hydraulic fracturing and stimulation of fracture networks are widely used by the energy industry (e.g., shale gas extraction, enhanced geothermal systems) to increase permeability of geological formations. Numerous analytical and numerical models have been developed to help understand and predict the behavior of hydraulically induced fractures. However, many existing models assume simple fracturing scenarios with highly idealized fracture geometries (e.g., propagation of a single fracture with assumed shapes in a homogeneous medium). Modeling hydraulic fracture propagation in the presence of natural fractures and homogeneities can be very challenging because of the complex interactions between fluid, rock matrix, and rock interfaces, as well as the interactions between propagating fractures and pre-existing natural fractures. In this study, the TOUGH-RBSN code for coupled hydro-mechanical modeling is utilized to simulate hydraulic fracture propagation and its interaction with pre-existing fracture networks. The simulation tool combines TOUGH2, a simulator of subsurface multiphase flow and mass transport based on the finite volume approach, with the implementation of a lattice modeling approach for geomechanical and fracture-damage behavior, named Rigid-Body-Spring Network (RBSN). The discrete fracture network (DFN) approach is facilitated in the Voronoi discretization via a fully automated modeling procedure. The numerical program is verified through a simple simulation for single fracture propagation, in which the resulting fracture geometry is compared to an analytical solution for given fracture length and aperture. Subsequently, predictive simulations are conducted for planned laboratory experiments using rock-analogue (soda-lime glass) samples containing a designed, pre-existing fracture network. The results of a preliminary simulation demonstrate selective fracturing and fluid infiltration along the pre-existing fractures, with additional fracturing in part
A Review on Mechanical and Hydraulic System Modeling of Excavator Manipulator System
Directory of Open Access Journals (Sweden)
Jiaqi Xu
2016-01-01
Full Text Available A recent trend in the development of off-highway construction equipment, such as excavators, is to use a system model for model-based system design in a virtual environment. Also, control system design for advanced excavation systems, such as automatic excavators and hybrid excavators, requires system models in order to design and simulate the control systems. Therefore, modeling of an excavator is an important first step toward the development of advanced excavators. This paper reviews results of recent studies on the modeling of mechanical and hydraulic subsystems for the simulation, design, and control development of excavator systems. Kinematic and dynamic modeling efforts are reviewed first. Then, various approaches in the hydraulic system modeling are presented.
Voortman, B.R.; Bartholomeus, R.P.; Bodegom, van P.M.; Gooren, H.P.A.; Zee, van der S.E.A.T.M.; Witte, J.P.M.
2014-01-01
Evaporation from mosses and lichens can form a major component of the water balance, especially in ecosystems where mosses and lichens often grow abundantly, such as tundra, deserts and bogs. To facilitate moss representation in hydrological models, we parameterized the unsaturated hydraulic propert
Use of hydraulic models to identify and resolve design isssues in FGD systems
Energy Technology Data Exchange (ETDEWEB)
Strock, T.W. [Babcock & Wilcox, Alliance, OH (United States); Gohara, W.F. [Babcock & Wilcox, Barberton, OH (United States)
1995-06-01
The hydraulics within a wet flue gas desulfurization (FGD) scrubber involve several complex two-phase gas/liquid interactions that directly affect the scrubber pressure drop, mist elimination efficiency, and the mass transfer process of SO{sub 2} removal. Current industrial efforts to develop cost effective, high-efficiency wet FGD scrubbers are focusing, in part, on the hydraulics. The development of an experimental approach and test facility for understanding and optimizing wet scrubber flow characteristics has been completed. Hydraulic models simulate full-scale units and allow the designer to view the gas/liquid flow interactions. Modeling procedures for downsizing the wet scrubber for the laboratory have been developed and validated with field data comparisons. A one-eighth scale hydraulic model has been used to study several FGD scrubber design issues. Design changes to reduce capital and operating cost have been developed and tested. Recently, the model was used to design a commercial, uniform flow, high gas velocity absorber for the next generation of FGD systems.
Concentrated flow is often the dominant source of water erosion following disturbance on rangeland. Because of the lack of studies that explain the hydraulics of concentrated flow on rangelands, cropland-based equations have typically been used for rangeland hydrology and erosion modeling, leading t...
Chen, Chi-Yin; Chuang, Jen-Chen; Tu, Jia-Ying
2016-09-01
This paper proposes modified coefficients for the dynamic model of hydraulic journal bearing system that integrates the hydrodynamic and hydrostatic properties. In recent years, design of hydraulic bearing for machine tool attracts worldwide attention, because hydraulic bearings are able to provide higher capacity and accuracy with lower friction, compared to conventional bearing systems. In order to achieve active control of the flow pressure and enhance the operation accuracy, the dynamic model of hydraulic bearings need to be developed. Modified coefficients of hydrostatic stiffness, hydrodynamic stiffness, and squeeze damping of the dynamic model are presented in this work, which are derived referring to small displacement analysis from literature. The proposed modified coefficients and model, which consider the pressure variations, relevant geometry size, and fluid properties of the journal bearings, are able to characterise the hydrodynamic and hydrostatic properties with better precision, thus offering the following pragmatic contribution: (1) on-line prediction of the eccentricity and the position of the shaft in the face of external force that results in vibration; (2) development of active control system to regulate the supply flow pressure and to minimize the eccentricity of the shaft. Theoretical derivation and simulation results with different vibration cases are discussed to verify the proposed techniques.
Hydrologic and hydraulic modelling of the Nyl River floodplain Part 3 ...
African Journals Online (AJOL)
2007-01-01
Jan 1, 2007 ... by catchments which are experiencing continuing water resource ... Careful dam operation could ameliorate impacts in very dry years, however. .... decreases rapidly, reflecting the seasonal variability of the flood- ..... tions and some hydraulic modelling were carried out by the first ... Research Foundation.
Directory of Open Access Journals (Sweden)
Tairone Paiva Leão
2011-02-01
Full Text Available An accurate estimation of hydraulic fluxes in the vadose zone is essential for the prediction of water, nutrient and contaminant transport in natural systems. The objective of this study was to simulate the effect of variation of boundary conditions on the estimation of hydraulic properties (i.e. water content, effective unsaturated hydraulic conductivity and hydraulic flux in a one-dimensional unsaturated flow model domain. Unsaturated one-dimensional vertical water flow was simulated in a pure phase clay loam profile and in clay loam interlayered with silt loam distributed according to the third iteration of the Cantor Bar fractal object Simulations were performed using the numerical model Hydrus 1D. The upper and lower pressure heads were varied around average values of -55 cm for the near-saturation range. This resulted in combinations for the upper and lower constant head boundary conditions, respectively, of -50 and -60 cm, -40 and -70 cm, -30 and -80 cm, -20 and -90 cm, and -10 and -100 cm. For the drier range the average head between the upper and lower boundary conditions was set to -550 cm, resulting in the combinations -500 and -600 cm, -400 and -700 cm, -300 and -800 cm, -200 and -900 cm, and -100 and -1,000 cm, for upper and lower boundary conditions, respectively. There was an increase in water contents, fluxes and hydraulic conductivities with the increase in head difference between boundary conditions. Variation in boundary conditions in the pure phase and interlayered one-dimensional profiles caused significant deviations in fluxes, water contents and hydraulic conductivities compared to the simplest case (a head difference between the upper and lower constant head boundaries of 10 cm in the wetter range and 100 cm in the drier range.
Doroszkiewicz, J. M.; Romanowicz, R. J.
2016-12-01
The standard procedure of climate change impact assessment on future hydrological extremes consists of a chain of consecutive actions, starting from the choice of GCM driven by an assumed CO2 scenario, through downscaling of climatic forcing to a catchment scale, estimation of hydrological extreme indices using hydrological modelling tools and subsequent derivation of flood risk maps with the help of a hydraulic model. Among many possible sources of uncertainty, the main are the uncertainties related to future climate scenarios, climate models, downscaling techniques and hydrological and hydraulic models. Unfortunately, we cannot directly assess the impact of these different sources of uncertainties on flood risk in future due to lack of observations of future climate realizations. The aim of this study is an assessment of a relative impact of different sources of uncertainty on the uncertainty of flood risk maps. Due to the complexity of the processes involved, an assessment of total uncertainty of maps of inundation probability might be very computer time consuming. As a way forward we present an application of a hydraulic model simulator based on a nonlinear transfer function model for the chosen locations along the river reach. The transfer function model parameters are estimated based on the simulations of the hydraulic model at each of the model cross-sections. The study shows that the application of a simulator substantially reduces the computer requirements related to the derivation of flood risk maps under future climatic conditions. Biala Tarnowska catchment, situated in southern Poland is used as a case study. Future discharges at the input to a hydraulic model are obtained using the HBV model and climate projections obtained from the EUROCORDEX project. The study describes a cascade of uncertainty related to different stages of the process of derivation of flood risk maps under changing climate conditions. In this context it takes into account the
Initial insights from 2.5D hydraulic modeling of floods in Athabasca Valles, Mars
Keszthelyi, L.P.; Denlinger, R.P.; O'Connell, D. R. H.; Burr, D.M.
2007-01-01
We present the first application of a 2.5D hydraulic model to catastrophic floods on Mars. This model simulates flow over complex topography and incorporates flood dynamics that could not be modeled in the earlier 1D models. We apply this model to Athabasca Valles, the youngest outflow channel on Mars, investigating previous bank-full discharge estimates and utilizing the interpolated Mars Orbiter Laser Altimeter elevation map as input. We confirm that the bank-full assumption does not fit the observed landforms. Instead, the channel appears more deeply incised near the source. Flow modeling also identifies several areas of special interest, including a dry cataract that coincides with a region of predicted high erosion. However, artifacts in the elevation data strongly impacted estimated stages and velocities in other areas. More extensive connection between the flood hydraulics and observed landforms awaits improved topographic data.
A HORIZONTAL 2-D HYDRAULIC NUMERICAL MODEL AND IT'S APPLICATIONS TO FLOOD FORECAST
Institute of Scientific and Technical Information of China (English)
Minghui YU; Guolu YANG; Jinjun XU
2002-01-01
In this paper,a horizontal 2-D numerical model has been developed to simulate flow processes in dike burst. The finite difference method is used in computation. The model employs 2-D flow equations and can simulate complex flows when supercritical flow and sub-critical flow exist simultaneously such as hydraulic jumps. Several simulated results are worked out to demonstrate the applicability of the numerical model,such as flood propagation on a dry bed of a complex terrain.
A Strategy Tackling Local Minimum of Direct Search Method in Modeling a Hydraulic Actuator
Institute of Scientific and Technical Information of China (English)
刘云山; 陈晓辉
2013-01-01
A strategy for attacking the local minimum problem of direct search method is developed for modeling a hydraulic actuator. The Nelder-Mead direct search method is combined with Ordinary Least Squares which can used to optimize the parameters which the model function is in linear with. The model fitting results show that this strategy can reach a solution more close to the global minimum than the Nelder-Mead direct search method used alone.
Global river flood hazard maps: hydraulic modelling methods and appropriate uses
Townend, Samuel; Smith, Helen; Molloy, James
2014-05-01
Flood hazard is not well understood or documented in many parts of the world. Consequently, the (re-)insurance sector now needs to better understand where the potential for considerable river flooding aligns with significant exposure. For example, international manufacturing companies are often attracted to countries with emerging economies, meaning that events such as the 2011 Thailand floods have resulted in many multinational businesses with assets in these regions incurring large, unexpected losses. This contribution addresses and critically evaluates the hydraulic methods employed to develop a consistent global scale set of river flood hazard maps, used to fill the knowledge gap outlined above. The basis of the modelling approach is an innovative, bespoke 1D/2D hydraulic model (RFlow) which has been used to model a global river network of over 5.3 million kilometres. Estimated flood peaks at each of these model nodes are determined using an empirically based rainfall-runoff approach linking design rainfall to design river flood magnitudes. The hydraulic model is used to determine extents and depths of floodplain inundation following river bank overflow. From this, deterministic flood hazard maps are calculated for several design return periods between 20-years and 1,500-years. Firstly, we will discuss the rationale behind the appropriate hydraulic modelling methods and inputs chosen to produce a consistent global scaled river flood hazard map. This will highlight how a model designed to work with global datasets can be more favourable for hydraulic modelling at the global scale and why using innovative techniques customised for broad scale use are preferable to modifying existing hydraulic models. Similarly, the advantages and disadvantages of both 1D and 2D modelling will be explored and balanced against the time, computer and human resources available, particularly when using a Digital Surface Model at 30m resolution. Finally, we will suggest some
Development of thermal hydraulic models for the reliable regulatory auditing code
Energy Technology Data Exchange (ETDEWEB)
Chung, B. D.; Song, C. H.; Lee, Y. J.; Kwon, T. S.; Lee, S. W. [Korea Automic Energy Research Institute, Taejon (Korea, Republic of)
2004-02-15
The objective of this project is to develop thermal hydraulic models for use in improving the reliability of the regulatory auditing codes. The current year fall under the second step of the 3 year project, and the main researches were focused on the development of downcorner boiling model. During the current year, the bubble stream model of downcorner has been developed and installed in he auditing code. The model sensitivity analysis has been performed for APR1400 LBLOCA scenario using the modified code. The preliminary calculation has been performed for the experimental test facility using FLUENT and MARS code. The facility for air bubble experiment has been installed. The thermal hydraulic phenomena for VHTR and super critical reactor have been identified for the future application and model development.
Hydrological and hydraulic models for determination of flood-prone and flood inundation areas
Aksoy, Hafzullah; Sadan Ozgur Kirca, Veysel; Burgan, Halil Ibrahim; Kellecioglu, Dorukhan
2016-05-01
Geographic Information Systems (GIS) are widely used in most studies on water resources. Especially, when the topography and geomorphology of study area are considered, GIS can ease the work load. Detailed data should be used in this kind of studies. Because of, either the complication of the models or the requirement of highly detailed data, model outputs can be obtained fast only with a good optimization. The aim in this study, firstly, is to determine flood-prone areas in a watershed by using a hydrological model considering two wetness indexes; the topographical wetness index, and the SAGA (System for Automated Geoscientific Analyses) wetness index. The wetness indexes were obtained in the Quantum GIS (QGIS) software by using the Digital Elevation Model of the study area. Flood-prone areas are determined by considering the wetness index maps of the watershed. As the second stage of this study, a hydraulic model, HEC-RAS, was executed to determine flood inundation areas under different return period-flood events. River network cross-sections required for this study were derived from highly detailed digital elevation models by QGIS. Also river hydraulic parameters were used in the hydraulic model. Modelling technology used in this study is made of freely available open source softwares. Based on case studies performed on watersheds in Turkey, it is concluded that results of such studies can be used for taking precaution measures against life and monetary losses due to floods in urban areas particularly.
Modeling and Optimal Design of 3 Degrees of Freedom Helmholtz Resonator in Hydraulic System
Institute of Scientific and Technical Information of China (English)
GUAN Changbin; JIAO Zongxia
2012-01-01
Three degrees of freedom (3-DOF) Helmholtz resonator which consists of three cylindrical necks and cavities connected in series (neck-cavity-ncck-cavity-neck-cavity) is suitable to reduce flow pulsation in hydraulic system.A novel lumped parameter model (LPM) of 3-DOF Helmholtz resonator in hydraulic system is developed which considers the viscous friction loss of hydraulic fluid in the necks.Applying the Newton's second law of motion to the equivalent mechanical model of the resonator,closed-form expression of transmission loss and resonance frequency is presented.Based on the LPM,an optimal design method which employs rotate vector optimization method (RVOM) is proposed.The purpose of the optimal design is to search the resonator's unknown parameters so that its resonance frequencies can coincide with the pump-induced flow pulsation harmonics respectively.The optimal design method is realized to design 3-DOF Helmholtz resonator for a certain type of aviation piston pump hydraulic system.The optimization result shows the feasibility of this method,and the simulation under optimum parameters reveals that the LPM can get the same precision as transfer matrix method (TMM).
A Grey Box Model for the Hydraulics in a Creek
DEFF Research Database (Denmark)
Jonsdottir, Harpa; Jacobsen, Judith L.; Madsen, Henrik
1998-01-01
The Saint-Venant equation of mass balance is used to derive a stochastics lumped model, describing the dynamics of a cross-sectional area in a river. The unknown parameters of the model are estimated by combining the physical equation with a set of data, a method known as grey box modelling. The ...
A Grey Box Model for the Hydraulics in a Creek
DEFF Research Database (Denmark)
Jonsdottir, Harpa; Jacobsen, Judith L.; Madsen, Henrik
1998-01-01
The Saint-Venant equation of mass balance is used to derive a stochastics lumped model, describing the dynamics of a cross-sectional area in a river. The unknown parameters of the model are estimated by combining the physical equation with a set of data, a method known as grey box modelling...
DEFF Research Database (Denmark)
Pauwels, Valentijn; Balenzano, Anna; Satalino, Giuseppe
2009-01-01
It is widely recognized that Synthetic Aperture Radar (SAR) data are a very valuable source of information for the modeling of the interactions between the land surface and the atmosphere. During the last couple of decades, most of the research on the use of SAR data in hydrologic applications has...... been focused on the retrieval of land and biogeophysical parameters (e.g., soil moisture contents). One relatively unexplored issue consists of the optimization of soil hydraulic model parameters, such its, for example, hydraulic conductivity, values, through remote sensing. This is due to the fact...... that no direct relationships between the remote-sensing observations, more specifically radar backscatter values, and the parameter values can be derived. However, land surface models can provide these relationships. The objective of this paper is to retrieve a number of soil physical model parameters through...
Hydraulic model tests on modified Wave Dragon. Phase 3
Energy Technology Data Exchange (ETDEWEB)
Hald, T.; Lynggaard, J.
2002-11-01
The purpose of this report is to describe the model tests conducted with a new designed 2. generation WD model as well as obtained model test results. Tests are conducted as sequential reconstruction followed by physical model tests. All details concerning the reconstruction are found in Hald and Lynggaard (2001). Model tests and reconstruction are carried out during the phase 3 project: 'Wave Dragon. Reconstruction of an existing model in scale 1:50 and sequential tests of changes to the model geometry and mass distribution parameters' sponsored by the Danish Energy Agency (DEA) wave energy programme. The tests will establish a well documented basis for the development of a 1:4.5 scale prototype planned for testing Nissum Bredning, a sea inlet on the Danish West Coast. (au)
Energy Technology Data Exchange (ETDEWEB)
McGraw, D.; Oberlander, P.
2007-12-18
The purpose of this study is to report on the results of a preliminary modeling framework to investigate the causes of the large hydraulic gradient north of Yucca Mountain. This study builds on the Saturated Zone Site-Scale Flow and Transport Model (referenced herein as the Site-scale model (Zyvoloski, 2004a), which is a three-dimensional saturated zone model of the Yucca Mountain area. Groundwater flow was simulated under natural conditions. The model framework and grid design describe the geologic layering and the calibration parameters describe the hydrogeology. The Site-scale model is calibrated to hydraulic heads, fluid temperature, and groundwater flowpaths. One area of interest in the Site-scale model represents the large hydraulic gradient north of Yucca Mountain. Nearby water levels suggest over 200 meters of hydraulic head difference in less than 1,000 meters horizontal distance. Given the geologic conceptual models defined by various hydrogeologic reports (Faunt, 2000, 2001; Zyvoloski, 2004b), no definitive explanation has been found for the cause of the large hydraulic gradient. Luckey et al. (1996) presents several possible explanations for the large hydraulic gradient as provided below: The gradient is simply the result of flow through the upper volcanic confining unit, which is nearly 300 meters thick near the large gradient. The gradient represents a semi-perched system in which flow in the upper and lower aquifers is predominantly horizontal, whereas flow in the upper confining unit would be predominantly vertical. The gradient represents a drain down a buried fault from the volcanic aquifers to the lower Carbonate Aquifer. The gradient represents a spillway in which a fault marks the effective northern limit of the lower volcanic aquifer. The large gradient results from the presence at depth of the Eleana Formation, a part of the Paleozoic upper confining unit, which overlies the lower Carbonate Aquifer in much of the Death Valley region. The
Directory of Open Access Journals (Sweden)
Hong-jun BAO
2011-03-01
Full Text Available A real-time channel flood forecast model was developed to simulate channel flow in plain rivers based on the dynamic wave theory. Taking into consideration channel shape differences along the channel, a roughness updating technique was developed using the Kalman filter method to update Manning’s roughness coefficient at each time step of the calculation processes. Channel shapes were simplified as rectangles, triangles, and parabolas, and the relationships between hydraulic radius and water depth were developed for plain rivers. Based on the relationship between the Froude number and the inertia terms of the momentum equation in the Saint-Venant equations, the relationship between Manning’s roughness coefficient and water depth was obtained. Using the channel of the Huaihe River from Wangjiaba to Lutaizi stations as a case, to test the performance and rationality of the present flood routing model, the original hydraulic model was compared with the developed model. Results show that the stage hydrographs calculated by the developed flood routing model with the updated Manning’s roughness coefficient have a good agreement with the observed stage hydrographs. This model performs better than the original hydraulic model.
3D integrated modeling approach to geo-engineering objects of hydraulic and hydroelectric projects
Institute of Scientific and Technical Information of China (English)
ZHONG DengHua; LI MingChao; LIU Jie
2007-01-01
Aiming at 3D modeling and analyzing problems of hydraulic and hydroelectric engineering geology, a complete scheme of solution is presented. The first basis was NURBS-TIN-BRep hybrid data structure. Then, according to the classified thought of the object-oriented technique, the different 3D models of geological and engineering objects were realized based on the data structure, including terrain class,strata class, fault class, and limit class; and the modeling mechanism was alternative. Finally, the 3D integrated model was established by Boolean operations between 3D geological objects and engineering objects. On the basis of the 3D model,a series of applied analysis techniques of hydraulic and hydroelectric engineering geology were illustrated. They include the visual modeling of rock-mass quality classification, the arbitrary slicing analysis of the 3D model, the geological analysis of the dam, and underground engineering. They provide powerful theoretical principles and technical measures for analyzing the geological problems encountered in hydraulic and hydroelectric engineering under complex geological conditions.
3D integrated modeling approach to geo-engineering objects of hydraulic and hydroelectric projects
Institute of Scientific and Technical Information of China (English)
2007-01-01
Aiming at 3D modeling and analyzing problems of hydraulic and hydroelectric en-gineering geology,a complete scheme of solution is presented. The first basis was NURBS-TIN-BRep hybrid data structure. Then,according to the classified thought of the object-oriented technique,the different 3D models of geological and engi-neering objects were realized based on the data structure,including terrain class,strata class,fault class,and limit class;and the modeling mechanism was alterna-tive. Finally,the 3D integrated model was established by Boolean operations be-tween 3D geological objects and engineering objects. On the basis of the 3D model,a series of applied analysis techniques of hydraulic and hydroelectric engineering geology were illustrated. They include the visual modeling of rock-mass quality classification,the arbitrary slicing analysis of the 3D model,the geological analysis of the dam,and underground engineering. They provide powerful theoretical prin-ciples and technical measures for analyzing the geological problems encountered in hydraulic and hydroelectric engineering under complex geological conditions.
DEFF Research Database (Denmark)
Dam Jensen, Mette; Ingildsen, Pernille; Rasmussen, Michael R.;
2005-01-01
shown to be more effective than others. To improve the design of less effective plants Computational Fluid Dynamics (CFD) modelling of hydraulics and sedimentation has been applied. The paper discusses the results at one particular plant experiencing problems with partly short-circuiting of the inlet...... been suggested and tested by means of computational fluid dynamics modelling. The most promissing design change have been found and reported....
Prototype Data Models and Data Dictionaries for Hanford Sediment Physical and Hydraulic Properties
Energy Technology Data Exchange (ETDEWEB)
Rockhold, Mark L.; Last, George V.; Middleton, Lisa A.
2010-09-30
The Remediation Decision Support (RDS) project, managed by the Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) and the CH2M HILL Plateau Remediation Company (CHPRC), has been compiling physical and hydraulic property data and parameters to support risk analyses and waste management decisions at Hanford. In FY09 the RDS project developed a strategic plan for a physical and hydraulic property database. This report documents prototype data models and dictionaries for these properties and associated parameters. Physical properties and hydraulic parameters and their distributions are required for any type of quantitative assessment of risk and uncertainty associated with predictions of contaminant transport and fate in the subsurface. The central plateau of the Hanford Site in southeastern Washington State contains most of the contamination at the Site and has up to {approx}100 m of unsaturated and unconsolidated or semi-consolidated sediments overlying the unconfined aquifer. These sediments contain a wide variety of contaminants ranging from organic compounds, such as carbon tetrachloride, to numerous radionuclides including technetium, plutonium, and uranium. Knowledge of the physical and hydraulic properties of the sediments and their distributions is critical for quantitative assessment of the transport of these contaminants in the subsurface, for evaluation of long-term risks and uncertainty associated with model predictions of contaminant transport and fate, and for evaluating, designing, and operating remediation alternatives. One of the goals of PNNL's RDS project is to work with the Hanford Environmental Data Manager (currently with CHPRC) to develop a protocol and schedule for incorporation of physical property and hydraulic parameter datasets currently maintained by PNNL into HEIS. This requires that the data first be reviewed to ensure quality and consistency. New data models must then be developed for HEIS that are
A model for hydraulic redistribution incorporating coupled soil-root moisture transport
Directory of Open Access Journals (Sweden)
G. G. Amenu
2007-10-01
Full Text Available One of the adaptive strategies of vegetation, particularly in water limited ecosystems, is the development of deep roots and the use of hydraulic redistribution which enables them to make optimal use of resources available throughout the soil column. Hydraulic redistribution refers to roots acting as a preferential pathway for the movement of water from wet to dry soil layers driven by the moisture gradient – be it from the shallow to deep layers or vice versa. This occurs during the nighttime while during the daytime moisture movement is driven to fulfill the transpiration demand at the canopy. In this study, we develop a model to investigate the effect of hydraulic redistribution by deep roots on the terrestrial climatology. Sierra Nevada eco-region is chosen as the study site which has wet winters and dry summers. Hydraulic redistribution enables the movement of moisture from the upper soil layers to deeper zones during the wet months and this moisture is then available to meet the transpiration demand during the late dry season. It results in significant alteration of the profiles of soil moisture and water uptake as well as increase in the canopy transpiration, carbon assimilation, and the associated water-use-efficiency during the dry summer season. This also makes the presence of roots in deeper soil layers much more important than their proportional abundance would otherwise dictate. Comparison with observations of latent heat from a flux tower demonstrates improved predictability and provides validation of the model results. Hydraulic redistribution serves as a mechanism for the interaction between the variability of deep layer soil-moisture and the land-surface climatology and could have significant implications for seasonal and sub-seasonal climate prediction.
A model for hydraulic redistribution incorporating coupled soil-root moisture transport
Directory of Open Access Journals (Sweden)
G. G. Amenu
2008-01-01
Full Text Available One of the adaptive strategies of vegetation, particularly in water limited ecosystems, is the development of deep roots and the use of hydraulic redistribution which enables them to make optimal use of resources available throughout the soil column. Hydraulic redistribution refers to roots acting as a preferential pathway for the movement of water from wet to dry soil layers driven by the moisture gradient – be it from the shallow to deep layers or vice versa. This occurs during the nighttime while during the daytime moisture movement is driven to fulfill the transpiration demand at the canopy. In this study, we develop a model to investigate the effect of hydraulic redistribution by deep roots on the terrestrial climatology. Sierra Nevada eco-region is chosen as the study site which has wet winters and dry summers. Hydraulic redistribution enables the movement of moisture from the upper soil layers to deeper zones during the wet months and this moisture is then available to meet the transpiration demand during the late dry season. It results in significant alteration of the profiles of soil moisture and water uptake as well as increase in the canopy transpiration, carbon assimilation, and the associated water-use-efficiency during the dry summer season. This also makes the presence of roots in deeper soil layers much more important than their proportional abundance would otherwise dictate. Comparison with observations of latent heat from a flux tower demonstrates improved predictability and provides validation of the model results. Hydraulic redistribution serves as a mechanism for the interaction between the variability of deep layer soil-moisture and the land-surface climatology and could have significant implications for seasonal and sub-seasonal climate prediction.
Digging Soil Experiments for Micro Hydraulic Excavators based on Model Predictive Tracking Control
Tomatsu, Takumi; Nonaka, Kenichiro; Sekiguchi, Kazuma; Suzuki, Katsumasa
2016-09-01
Recently, the increase of burden to operators and lack of skilled operators are the issue in the work of the hydraulic excavator. These problems are expected to be improved by autonomous control. In this paper, we present experimental results of hydraulic excavators using model predictive control (MPC) which incorporates servo mechanism. MPC optimizes digging operations by the optimal control input which is calculated by predicting the future states and satisfying the constraints. However, it is difficult for MPC to cope with the reaction force from soil when a hydraulic excavator performs excavation. Servo mechanism suppresses the influence of the constant disturbance using the error integration. However, the bucket tip deviates from a specified shape by the sudden change of the disturbance. We can expect that the tracking performance is improved by combining MPC and servo mechanism. Path-tracking controls of the bucket tip are performed using the optimal control input. We apply the proposed method to the Komatsu- made micro hydraulic excavator PC01 by experiments. We show the effectiveness of the proposed method through the experiment of digging soil by comparing servo mechanism and pure MPC with the proposed method.
Sañudo-Fontaneda, Luis A; Jato-Espino, Daniel; Lashford, Craig; Coupe, Stephen J
2017-05-23
Road drainage is one of the most relevant assets in transport infrastructure due to its inherent influence on traffic management and road safety. Highway filter drains (HFDs), also known as "French Drains", are the main drainage system currently in use in the UK, throughout 7000 km of its strategic road network. Despite being a widespread technique across the whole country, little research has been completed on their design considerations and their subsequent impact on their hydraulic performance, representing a gap in the field. Laboratory experiments have been proven to be a reliable indicator for the simulation of the hydraulic performance of stormwater best management practices (BMPs). In addition to this, stormwater management tools (SMT) have been preferentially chosen as a design tool for BMPs by practitioners from all over the world. In this context, this research aims to investigate the hydraulic performance of HFDs by comparing the results from laboratory simulation and two widely used SMT such as the US EPA's stormwater management model (SWMM) and MicroDrainage®. Statistical analyses were applied to a series of rainfall scenarios simulated, showing a high level of accuracy between the results obtained in laboratory and using SMT as indicated by the high and low values of the Nash-Sutcliffe and R (2) coefficients and root-mean-square error (RMSE) reached, which validated the usefulness of SMT to determine the hydraulic performance of HFDs.
Energy Technology Data Exchange (ETDEWEB)
Vrugt, Jasper A [Los Alamos National Laboratory; Wohling, Thomas [NON LANL
2008-01-01
Most studies in vadose zone hydrology use a single conceptual model for predictive inference and analysis. Focusing on the outcome of a single model is prone to statistical bias and underestimation of uncertainty. In this study, we combine multi-objective optimization and Bayesian Model Averaging (BMA) to generate forecast ensembles of soil hydraulic models. To illustrate our method, we use observed tensiometric pressure head data at three different depths in a layered vadose zone of volcanic origin in New Zealand. A set of seven different soil hydraulic models is calibrated using a multi-objective formulation with three different objective functions that each measure the mismatch between observed and predicted soil water pressure head at one specific depth. The Pareto solution space corresponding to these three objectives is estimated with AMALGAM, and used to generate four different model ensembles. These ensembles are post-processed with BMA and used for predictive analysis and uncertainty estimation. Our most important conclusions for the vadose zone under consideration are: (1) the mean BMA forecast exhibits similar predictive capabilities as the best individual performing soil hydraulic model, (2) the size of the BMA uncertainty ranges increase with increasing depth and dryness in the soil profile, (3) the best performing ensemble corresponds to the compromise (or balanced) solution of the three-objective Pareto surface, and (4) the combined multi-objective optimization and BMA framework proposed in this paper is very useful to generate forecast ensembles of soil hydraulic models.
A nonlocal model for fluid-structure interaction with applications in hydraulic fracturing
Turner, Daniel Z
2012-01-01
Modeling important engineering problems related to flow-induced damage (in the context of hydraulic fracturing among others) depends critically on characterizing the interaction of porous media and interstitial fluid flow. This work presents a new formulation for incorporating the effects of pore pressure in a nonlocal representation of solid mechanics. The result is a framework for modeling fluid-structure interaction problems with the discontinuity capturing advantages of an integral based formulation. A number of numerical examples are used to show that the proposed formulation can be applied to measure the effect of leak-off during hydraulic fracturing as well as modeling consolidation of fluid saturated rock and surface subsidence caused by fluid extraction from a geologic reservoir. The formulation incorporates the effect of pore pressure in the constitutive description of the porous material in a way that is appropriate for nonlinear materials, easily implemented in existing codes, straightforward in i...
Sánchez, F; Viedma, A; Kaiser, A S
2016-09-15
Fluid dynamic behaviour plays an important role in wastewater treatment. An efficient treatment requires the inexistence of certain hydraulic problems such as dead zones or short-circuiting flows. Residence time distribution (RTD) analysis is an excellent technique for detecting these inefficiencies. However, many wastewater treatment installations include water or sludge recycling systems, which prevent us from carrying out a conventional tracer pulse experiment to obtain the RTD curve of the installation. This paper develops an RTD analysis of an activated sludge reactor with recycling system. A tracer experiment in the reactor is carried out. Three analytical models, derived from the conventional pulse model, are proposed to obtain the RTD curve of the reactor. An analysis of the results is made, studying which model is the most suitable for each situation. This paper is useful to analyse the hydraulic efficiency of reactors with recycling systems.
Institute of Scientific and Technical Information of China (English)
CHU Deying; ZHANG Zhiyi; WANG Gongxian; HUA Hongxing
2007-01-01
A high fidelity dynamic model of a high-energy hydraulically-actuated shock test machine for heavy weight devices is presented to satisfy the newly-built shock resistance standard and simulate the actual underwater explosion environments in laboratory as well as increase the testing capability of shock test machine. In order to produce the required negative shock pulse in the given time duration, four hydraulic actuators are utilized. The model is then used to formulate an advanced feedforward controller for the system to produce the required negative waveform and to address the motion synchronization of the four cylinders. The model provides a safe and easily controllable way to perform a "virtual testing" before starting potentially destructive tests on specimen and to predict performance of the system. Simulation results have demonstrated the effectiveness of the controller.
On Model Libraries for Thermo-hydraulic Applications
Eborn, Jonas
2001-01-01
Mathematical modelling and simulation are important tools when dealing with engineering systems that today are becoming increasingly more complex. Tightly integrated production and process optimization are trends that give rise to heterogeneous systems, which are difficult to handle without expertise in several engineering disciplines. Model libraries provide an excellent way to package engineering knowledge of systems and units to be reused by non experts. Many commercial simulation packages...
Dynamic Modeling of Hydraulic Power Steering System with Variable Ratio Rack and Pinion Gear
Zhang, Nong; Wang, Miao
A comprehensive mathematical model of a typical hydraulic power steering system equipped with variable ratio rack and pinion gear is developed. The steering system’s dynamic characteristics are investigated and its forced vibrations are compared with those obtained from a counterpart system with a constant ratio rack and pinion gear. The modeling details of the mechanism subsystem, hydraulic supply lines subsystem and the rotary spool valve subsystem are provided and included in the integrated steering system model. The numerical simulations are conducted to investigate the dynamics of the nonlinear parametric steering system. From the comparison between simulated results and the experimental ones, it is shown that the model accurately integrates the boost characteristics of the rotary spool valve which is the key component of hydraulic power steering system. The variable ratio rack-pinion gear behaviors significantly differently from its constant ratio counterpart does. It significantly affects not only the system natural frequencies but also reduces vibrations under constant rate and ramp torque steering inputs. The developed steering model produces valid predictions of the system’s behavior and therfore could assist engineers in the design and analysis of integrated steering systems.
DEFF Research Database (Denmark)
Zhang, Donghua; Madsen, Henrik; Ridler, Marc E.
2015-01-01
uncertainty. In most hydrological EnKF applications, an ad hoc model uncertainty is defined with the aim of avoiding a collapse of the filter. The present work provides a systematic assessment of model uncertainty in DA applications based on combinations of forcing, model parameters, and state uncertainties....... This is tested in a case where groundwater hydraulic heads are assimilated into a distributed and integrated catchment-scale model of the Karup catchment in Denmark. A series of synthetic data assimilation experiments are carried out to analyse the impact of different model uncertainty assumptions...
Energy Technology Data Exchange (ETDEWEB)
Sonoda, K.; Nakamura, Y.; Kajima, T.; Sato, S.; Fujii, T.; Tobe, Y. (Kawasaki Heavy Industries, Ltd., Tokyo (Japan))
1992-07-20
This paper describes new hydraulically-actuated mechanisms for both fuel injection and inlet/exhaust valve operation of diesel engines through solenoid valves, which obviate the conventional cam-driven system. These mechanisms were integrated with an electronic control unit also developed in this study and they were mounted as a mechatronics system'' on a power-increased single-cylinder engine. This mechatronics system was mainly composed of an injection control. boost and accumulation component, an inlet and exhaust valve control component, a solenoid valve, an electronic control equipment, a hydraulic power unit, and a maneuvering unit. The verification test was carried out for the improvement of diesel engine performance by the hydraulically powered mechatronics system. As a result, it was proved not only that these mechanisms provide stable operating characteristics over a wide range of conditions, but also that the electronic control system allows accurate, smooth response. 3 refs., 23 figs., 2 tabs.
Perkins, Kim S.; Winfield, Kari A.
2007-01-01
The unsaturated zone at the Idaho National Laboratory is complex, comprising thick basalt flow sequences interbedded with thinner sedimentary layers. Understanding the highly nonlinear relation between water content and hydraulic conductivity within the sedimentary interbeds is one element in predicting water flow and solute transport processes in this geologically complex environment. Measurement of unsaturated hydraulic conductivity of sediments is costly and time consuming, therefore use of models that estimate this property from more easily measured bulk-physical properties is desirable. A capillary bundle model was used to estimate unsaturated hydraulic conductivity for 40 samples from sedimentary interbeds using water-retention parameters and saturated hydraulic conductivity derived from (1) laboratory measurements on core samples, and (2) site-specific property transfer regression models developed for the sedimentary interbeds. Four regression models were previously developed using bulk-physical property measurements (bulk density, the median particle diameter, and the uniformity coefficient) as the explanatory variables. The response variables, estimated from linear combinations of the bulk physical properties, included saturated hydraulic conductivity and three parameters that define the water-retention curve. The degree to which the unsaturated hydraulic conductivity curves estimated from property-transfer-modeled water-retention parameters and saturated hydraulic conductivity approximated the laboratory-measured data was evaluated using a goodness-of-fit indicator, the root-mean-square error. Because numerical models of variably saturated flow and transport require parameterized hydraulic properties as input, simulations were run to evaluate the effect of the various parameters on model results. Results show that the property transfer models based on easily measured bulk properties perform nearly as well as using curve fits to laboratory-measured water
Huisman, J. A.; Rings, J.; Vrugt, J. A.; Sorg, J.; Vereecken, H.
2010-01-01
SummaryCoupled hydrogeophysical inversion aims to improve the use of geophysical data for hydrological model parameterization. Several numerical studies have illustrated the feasibility and advantages of a coupled approach. However, there is still a lack of studies that apply the coupled inversion approach to actual field data. In this paper, we test the feasibility of coupled hydrogeophysical inversion for determining the hydraulic properties of a model dike using measurements of electrical resistance tomography (ERT). Our analysis uses a two-dimensional (2D) finite element hydrological model (HYDRUS-2D) coupled to a 2.5D finite element electrical resistivity code (CRMOD), and includes explicit recognition of parameter uncertainty by using a Bayesian and multiple criteria framework with the DREAM and AMALGAM population based search algorithms. To benchmark our inversion results, soil hydraulic properties determined from ERT data are compared with those separately obtained from detailed in situ soil water content measurements using Time Domain Reflectometry (TDR). Our most important results are as follows. (1) TDR and ERT data theoretically contain sufficient information to resolve most of the soil hydraulic properties, (2) the DREAM-derived posterior distributions of the hydraulic parameters are quite similar when estimated separately using TDR and ERT measurements for model calibration, (3) among all parameters, the saturated hydraulic conductivity of the dike material is best constrained, (4) the saturation exponent of the petrophysical model is well defined, and matches independently measured values, (5) measured ERT data sufficiently constrain model predictions of water table dynamics within the model dike. This finding demonstrates an innate ability of ERT data to provide accurate hydrogeophysical parameterizations for flooding events, which is of particular relevance to dike management, and (6) the AMALGAM-derived Pareto front demonstrates trade-off in the
Kornilin, DV; Kudryavtsev, IA
2016-10-01
One of the most effective ways to diagnose the state of hydraulic system is an investigation of the particles in their liquids. The sizes of such particles range from 2 to 200 gm and their concentration and shape reveal important information about the current state of equipment and the necessity of maintenance. In-line automatic particle counters (APC), which are built into hydraulic system, are widely used for determination of particle size and concentration. These counters are based on a single photodiode and a light emitting diode (LED); however, samples of liquid are needed for analysis using microscope or industrial video camera in order to get information about particle shapes. The act of obtaining the sample leads to contamination by other particles from the air or from the sample tube, meaning that the results are usually corrupted. Using the CMOS or CCD matrix sensor without any lens for inline APC is the solution proposed by authors. In this case the matrix sensors are put into the liquid channel of the hydraulic system and illuminated by LED. This system could be stable in arduous conditions like high pressure and the vibration of the hydraulic system; however, the image or signal from that matrix sensor needs to be processed differently in comparison with the signal from microscope or industrial video camera because of relatively short distance between LED and sensor. This paper introduces mathematical model of a sensor with CMOS and LED, which can be built into hydraulic system. It is also provided a computational algorithm and results, which can be useful for calculation of particle sizes and shapes using the signal from the CMOS matrix sensor.
Hydrodynamic Forces on Reverse Tainter Valves; Hydraulic Model Investigation
2013-12-01
FACILITY: Completion of a physical model study of the culvert valves of the Eisenhower and Snell Locks, St. Lawrence Seaway (Stockstill et al., in...evaluation of culvert valves at Eisenhower and Snell Locks, St. Lawrence Seaway. Vicksburg, MS: US Army Engineer Research and Development Center
Storm Water Management Model Reference Manual Volume II – Hydraulics
SWMM is a dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. The runoff component of SWMM operates on a collection of subcatchment areas that receive precipitation and gene...
Directory of Open Access Journals (Sweden)
S. Oehlmann
2013-07-01
Full Text Available Due to their heterogeneous nature, karst aquifers pose a major challenge for hydrogeological investigations. Important procedures like the delineation of catchment areas for springs are hindered by the unknown locations and hydraulic properties of highly conductive karstic zones. In this work numerical modeling was employed as a tool in delineating catchment areas of several springs within a karst area in southwestern Germany. For this purpose, different distributive modeling approaches were implemented in the Finite Element simulation software Comsol Multiphysics®. The investigation focuses on the question to which degree the effect of karstification has to be taken into account for accurately simulating the hydraulic head distribution and the observed spring discharges. The results reveal that the representation of heterogeneities has a large influence on the delineation of the catchment areas. Not only the location of highly conductive elements but also their geometries play a major role for the resulting hydraulic head distribution and thus for catchment area delineation. The size distribution of the karst conduits derived from the numerical models agrees with knowledge from karst genesis. It was thus shown that numerical modeling is a useful tool for catchment delineation in karst aquifers based on results from different field observations.
Numerical modeling for the retrofit of the hydraulic cooling subsystems in operating power plant
AlSaqoor, S.; Alahmer, A.; Al Quran, F.; Andruszkiewicz, A.; Kubas, K.; Regucki, P.; Wędrychowicz, W.
2017-08-01
This paper presents the possibility of using the numerical methods to analyze the work of hydraulic systems on the example of a cooling system of a power boiler auxiliary devices. The variety of conditions at which hydraulic system that operated in specific engineering subsystems requires an individualized approach to the model solutions that have been developed for these systems modernizing. A mathematical model of a series-parallel propagation for the cooling water was derived and iterative methods were used to solve the system of nonlinear equations. The results of numerical calculations made it possible to analyze different variants of a modernization of the studied system and to indicate its critical elements. An economic analysis of different options allows an investor to choose an optimal variant of a reconstruction of the installation.
Roubinet, D; Jougnot, D; Irving, J
2016-01-01
Numerous field experiments suggest that the self-potential (SP) geophysical method may allow for the detection of hydraulically active fractures and provide information about fracture properties. However, a lack of suitable numerical tools for modeling streaming potentials in fractured media prevents quantitative interpretation and limits our understanding of how the SP method can be used in this regard. To address this issue, we present a highly efficient two-dimensional discrete-dual-porosity approach for solving the fluid flow and associated self-potential problems in fractured rock. Our approach is specifically designed for complex fracture networks that cannot be investigated using standard numerical methods. We then simulate SP signals associated with pumping conditions for a number of examples to show that (i) accounting for matrix fluid flow is essential for accurate SP modeling and (ii) the sensitivity of SP to hydraulically active fractures is intimately linked with fracture-matrix fluid interaction...
Development of a river ice jam by a combined heat loss and hydraulic model
Eliasson, J.; Gröndal, G. O.
2008-11-01
The heat loss theory and the hydraulic theory for the analysis of the development of wide channel ice jams are discussed and shown. The heat loss theory has been used in Iceland for a long time, while the hydraulic theory largely follows the classical ice-jam build-up theories used in known CFD models. The results are combined in a new method to calculate the maximum thickness and the extent of an ice jam. The results compare favorably to the HEC-RAS model for the development of a very large ice jam in Thjorsa River in Iceland, and have been found in good agreement with historical data, collected where a hydroelectric dam project, Urridafoss, is being planned in the Thjorsa River.
Habitat hydraulic models - a tool for Danish stream quality assessment?
DEFF Research Database (Denmark)
Olsen, Martin
observations and "site-specific" habitat suitability indices (HSI) are constructed. "Site-specific" HSI's are compared to other HSI's for Danish streams (Søholm and Jensen, 2003) and general HSI's used in other habitat hydraulic modelling projects (Lund, 1996; Fjordback et al. 2002; Thorn and Conallin, 2004...... and hydromorphological and chemical characteristics has to be enlightened (EUROPA, 2005). This study links catchment hydrology, stream discharge and physical habitat in a small Danish stream, the stream Ledreborg, and discusses the utility of habitat hydraulic models in relation to the present criteria and methods used...... groundwater abstraction upon stream discharge is assessed and in relation to this the relative importance of variations in precipitation, evaporation/temperature and groundwater abstraction are discussed. Physical habitat preferences for trout in the stream Ledreborg are assessed through a series of field...
Development of a river ice jam by a combined heat loss and hydraulic model
Directory of Open Access Journals (Sweden)
J. Eliasson
2008-11-01
Full Text Available The heat loss theory and the hydraulic theory for the analysis of the development of wide channel ice jams are discussed and shown. The heat loss theory has been used in Iceland for a long time, while the hydraulic theory largely follows the classical ice-jam build-up theories used in known CFD models. The results are combined in a new method to calculate the maximum thickness and the extent of an ice jam. The results compare favorably to the HEC-RAS model for the development of a very large ice jam in Thjorsa River in Iceland, and have been found in good agreement with historical data, collected where a hydroelectric dam project, Urridafoss, is being planned in the Thjorsa River.
Hydrogeological model of the territory of Kowsar hydraulic project
Directory of Open Access Journals (Sweden)
Orekhov Vyacheslav Valentinovich
2015-03-01
Full Text Available Mathematical hydrogeology model of the territory of Kowsar Project was created with account for the results of the engineering surveys and hydro geological monitoring, which was conducted in the process of Kowsar Project construction. In order to create the model in the present work a universal computer system Ansys was used, which implements the finite element method and solid modeling technology, allowing to solve the filtration problem with the use of thermal analogy. The three-dimensional geometric model was built with use of the principle “hard body” modeling, which displays the main line of the territory relief, including the created water reservoir, geological structure (anticline Duk and the main lithological complexes developed within the territory. In the limestone mass As here is a zone characterized by water permeability on territory of Kowsar Project, and a layer characterized by seepage feeding, which occurs outside the considered territory. The water reservoir is a source of the change of hydro geological situation. The results of field observations witness, that the levels of underground waters within the area of the main structures reacts almost instantly on the water level change in the water reservoir; the delay period of levels change is not more than 1,5…2,0 weeks at maximum distance from the water reservoir. These particularities of the hydro geological regime allow using the steady-state scheme of the decision of forecast problems. The mass of limestone As, containing the structures of the Kowsar Project, is not homogeneous and anisotropy in its seepage characteristics. The heterogeneity is conditioned by exogenous influence on the mass up to the depth of 100…150 m. The seepage anisotropy of the mass is expressed by the difference of water permeability of the mass along and across the layers for almost one order. The structures of Kowsar Project is presented by a dam, grouting curtain on axis of the dam and
Modeling thermal stress propagation during hydraulic stimulation of geothermal wells
Jansen, Gunnar; Miller, Stephen A.
2017-04-01
A large fraction of the world's water and energy resources are located in naturally fractured reservoirs within the earth's crust. Depending on the lithology and tectonic history of a formation, fracture networks can range from dense and homogeneous highly fractured networks to single large scale fractures dominating the flow behavior. Understanding the dynamics of such reservoirs in terms of flow and transport is crucial to successful application of engineered geothermal systems (also known as enhanced geothermal systems or EGS) for geothermal energy production in the future. Fractured reservoirs are considered to consist of two distinct separate media, namely the fracture and matrix space respectively. Fractures are generally thin, highly conductive containing only small amounts of fluid, whereas the matrix rock provides high fluid storage but typically has much smaller permeability. Simulation of flow and transport through fractured porous media is challenging due to the high permeability contrast between the fractures and the surrounding rock matrix. However, accurate and efficient simulation of flow through a fracture network is crucial in order to understand, optimize and engineer reservoirs. It has been a research topic for several decades and is still under active research. Accurate fluid flow simulations through field-scale fractured reservoirs are still limited by the power of current computer processing units (CPU). We present an efficient implementation of the embedded discrete fracture model, which is a promising new technique in modeling the behavior of enhanced geothermal systems. An efficient coupling strategy is determined for numerical performance of the model. We provide new insight into the coupled modeling of fluid flow, heat transport of engineered geothermal reservoirs with focus on the thermal stress changes during the stimulation process. We further investigate the interplay of thermal and poro-elastic stress changes in the reservoir
Modelling and Simulation of Mobile Hydraulic Crane with Telescopic Arm
DEFF Research Database (Denmark)
Nielsen, Brian; Pedersen, Henrik Clemmensen; Andersen, Torben Ole
2005-01-01
For loader crane applications resolved motion control is assumed to be one of the areas for development in the future. To develop and evaluate different control strategies for a resolved motion control system, information about the dynamic behaviour of these cranes is necessary. In the current pa...... the relative movement of the individual mechanical bodies in the telescopic arm. The model is verified through comparisons between simulated and measured results for various operating conditions....
U.S. Geological Survey, Department of the Interior — A three-dimensional, groundwater-flow model (MODFLOW-2005) was developed to estimate the hydraulic properties (e.g., transmissivity, hydraulic conductivity, specific...
Gutmann, Ethan D.; Small, Eric E.
2007-01-01
Soil hydraulic properties (SHPs) regulate the movement of water in the soil. This in turn plays an important role in the water and energy cycles at the land surface. At present, SHPS are commonly defined by a simple pedotransfer function from soil texture class, but SHPs vary more within a texture class than between classes. To examine the impact of using soil texture class to predict SHPS, we run the Noah land surface model for a wide variety of measured SHPs. We find that across a range of vegetation cover (5 - 80% cover) and climates (250 - 900 mm mean annual precipitation), soil texture class only explains 5% of the variance expected from the real distribution of SHPs. We then show that modifying SHPs can drastically improve model performance. We compare two methods of estimating SHPs: (1) inverse method, and (2) soil texture class. Compared to texture class, inverse modeling reduces errors between measured and modeled latent heat flux from 88 to 28 w/m(exp 2). Additionally we find that with increasing vegetation cover the importance of SHPs decreases and that the van Genuchten m parameter becomes less important, while the saturated conductivity becomes more important.
Numerical models in hydraulic design; Numerische Modelle bei der wasserbaulichen Planung
Energy Technology Data Exchange (ETDEWEB)
Musall, M.; Stelzer, C.; Nestmann, F. [Technische Univ. Karlsruhe (DE). Inst. fuer Wasser und Gewaesserentwicklung (IWG); Theobald, S. [Technische Univ. Karlsruhe (DE). Inst. fuer Wasser und Gewaesserentwicklung (IWG); Kassel Univ. (Germany)
2006-07-01
By means of a practical example the significance of numerical modelling within a hybrid hydraulic planning process, which is based on the combination of several numerical and physical models, is shown. Thereby especially the interaction of the different applied numerical methods as well as the possibilities of numerical optimization of preliminary planning aiming on reduced construction costs of the laboratory models are pointed out. A detailed description of the additional laboratory models and their techniques is given by the article of Queisser et al. (orig.)
SToRM: A Model for 2D environmental hydraulics
Simões, Francisco J. M.
2017-01-01
A two-dimensional (depth-averaged) finite volume Godunov-type shallow water model developed for flow over complex topography is presented. The model, SToRM, is based on an unstructured cell-centered finite volume formulation and on nonlinear strong stability preserving Runge-Kutta time stepping schemes. The numerical discretization is founded on the classical and well established shallow water equations in hyperbolic conservative form, but the convective fluxes are calculated using auto-switching Riemann and diffusive numerical fluxes. Computational efficiency is achieved through a parallel implementation based on the OpenMP standard and the Fortran programming language. SToRM’s implementation within a graphical user interface is discussed. Field application of SToRM is illustrated by utilizing it to estimate peak flow discharges in a flooding event of the St. Vrain Creek in Colorado, U.S.A., in 2013, which reached 850 m3/s (~30,000 f3 /s) at the location of this study.
Directory of Open Access Journals (Sweden)
Paszota Zygmunt
2015-01-01
Full Text Available The objective of the work is to develop the capability of evaluating the volumetric losses of hydraulic oil compression in the working chambers of high pressure variable capacity displacement pump. Volumetric losses of oil compression must be determined as functions of the same parameters, which the volumetric losses due to leakage, resulting from the quality of design solution of the pump, are evaluated as dependent on and also as function of the oil aeration coefficient Ɛ. A mathematical model has been developed describing the hydraulic oil compressibility coefficient klc|Δppi;Ɛ;v as a relation to the ratio ΔpPi/pn of indicated increase ΔpPi of pressure in the working chambers and the nominal pressure pn, to the pump capacity coefficient bP, to the oil aeration coefficient and to the ratio v/vnof oil viscosity v and reference viscosity vn. A mathematical model is presented of volumetric losses qpvc|ΔpPi;bp;;vof hydraulic oil compression in the pump working chambers in the form allowing to use it in the model of power of losses and energy efficiency
Assessment of uncertainties of the models used in thermal-hydraulic computer codes
Gricay, A. S.; Migrov, Yu. A.
2015-09-01
The article deals with matters concerned with the problem of determining the statistical characteristics of variable parameters (the variation range and distribution law) in analyzing the uncertainty and sensitivity of calculation results to uncertainty in input data. A comparative analysis of modern approaches to uncertainty in input data is presented. The need to develop an alternative method for estimating the uncertainty of model parameters used in thermal-hydraulic computer codes, in particular, in the closing correlations of the loop thermal hydraulics block, is shown. Such a method shall feature the minimal degree of subjectivism and must be based on objective quantitative assessment criteria. The method includes three sequential stages: selecting experimental data satisfying the specified criteria, identifying the key closing correlation using a sensitivity analysis, and carrying out case calculations followed by statistical processing of the results. By using the method, one can estimate the uncertainty range of a variable parameter and establish its distribution law in the above-mentioned range provided that the experimental information is sufficiently representative. Practical application of the method is demonstrated taking as an example the problem of estimating the uncertainty of a parameter appearing in the model describing transition to post-burnout heat transfer that is used in the thermal-hydraulic computer code KORSAR. The performed study revealed the need to narrow the previously established uncertainty range of this parameter and to replace the uniform distribution law in the above-mentioned range by the Gaussian distribution law. The proposed method can be applied to different thermal-hydraulic computer codes. In some cases, application of the method can make it possible to achieve a smaller degree of conservatism in the expert estimates of uncertainties pertinent to the model parameters used in computer codes.
Shu, Jian-Jun
2014-01-01
A finite element model and its equivalent electronic analogue circuit of hydraulic transmission lines have been developed. Basic equations are approximated to be a set of ordinary differential equations that can be represented in state space form. The accuracy of the model is demonstrated by comparison with the method of characteristics.
Two and Three-Phases Fractal Models Application in Soil Saturated Hydraulic Conductivity Estimation
Directory of Open Access Journals (Sweden)
ELNAZ Rezaei abajelu
2017-03-01
Full Text Available Introduction: Soil Hydraulic conductivity is considered as one of the most important hydraulic properties in water and solutionmovement in porous media. In recent years, variousmodels as pedo-transfer functions, fractal models and scaling technique are used to estimate the soil saturated hydraulic conductivity (Ks. Fractal models with two subset of two (solid and pore and three phases (solid, pore and soil fractal (PSF are used to estimate the fractal dimension of soil particles. The PSF represents a generalization of the solid and pore mass fractal models. The PSF characterizes both the solid and pore phases of the porous material. It also exhibits self-similarity to some degree, in the sense that where local structure seems to be similar to the whole structure.PSF models can estimate interface fractal dimension using soil pore size distribution data (PSD and soil moisture retention curve (SWRC. The main objective of this study was to evaluate different fractal models to estimate the Ksparameter. Materials and Methods: The Schaapetal data was used in this study. The complex consists of sixty soil samples. Soil texture, soil bulk density, soil saturated hydraulic conductivity and soil particle size distribution curve were measured by hydrometer method, undistributed soil sample, constant head method and wet sieve method, respectively for all soil samples.Soil water retention curve were determined by using pressure plates apparatus.The Ks parameter could be estimated by Ralws model as a function of fractal dimension by seven fractal models. Fractal models included Fuentes at al. (1996, Hunt and Gee (2002, Bird et al. (2000, Huang and Zhang (2005, Tyler and Wheatcraft (1990, Kutlu et al. (2008, Sepaskhah and Tafteh (2013.Therefore The Ks parameter can be estimated as a function of the DS (fractal dimension by seven fractal models (Table 2.Sensitivity analysis of Rawls model was assessed by making changes±10%, ±20% and±30%(in input parameters
A Bayesian Chance-Constrained Method for Hydraulic Barrier Design Under Model Structure Uncertainty
Chitsazan, N.; Pham, H. V.; Tsai, F. T. C.
2014-12-01
The groundwater community has widely recognized the model structure uncertainty as the major source of model uncertainty in groundwater modeling. Previous studies in the aquifer remediation design, however, rarely discuss the impact of the model structure uncertainty. This study combines the chance-constrained (CC) programming with the Bayesian model averaging (BMA) as a BMA-CC framework to assess the effect of model structure uncertainty in the remediation design. To investigate the impact of the model structure uncertainty on the remediation design, we compare the BMA-CC method with the traditional CC programming that only considers the model parameter uncertainty. The BMA-CC method is employed to design a hydraulic barrier to protect public supply wells of the Government St. pump station from saltwater intrusion in the "1,500-foot" sand and the "1-700-foot" sand of the Baton Rouge area, southeastern Louisiana. To address the model structure uncertainty, we develop three conceptual groundwater models based on three different hydrostratigraphy structures. The results show that using the traditional CC programming overestimates design reliability. The results also show that at least five additional connector wells are needed to achieve more than 90% design reliability level. The total amount of injected water from connector wells is higher than the total pumpage of the protected public supply wells. While reducing injection rate can be achieved by reducing reliability level, the study finds that the hydraulic barrier design to protect the Government St. pump station is not economically attractive.
Temporal evolution modeling of hydraulic and water quality performance of permeable pavements
Huang, Jian; He, Jianxun; Valeo, Caterina; Chu, Angus
2016-02-01
A mathematical model for predicting hydraulic and water quality performance in both the short- and long-term is proposed based on field measurements for three types of permeable pavements: porous asphalt (PA), porous concrete (PC), and permeable inter-locking concrete pavers (PICP). The model was applied to three field-scale test sites in Calgary, Alberta, Canada. The model performance was assessed in terms of hydraulic parameters including time to peak, peak flow and water balance and a water quality variable (the removal rate of total suspended solids). A total of 20 simulated storm events were used for model calibration and verification processes. The proposed model can simulate the outflow hydrographs with a coefficient of determination (R2) ranging from 0.762 to 0.907, and normalized root-mean-square deviation (NRMSD) ranging from 13.78% to 17.83%. Comparison of the time to peak flow, peak flow, runoff volume and TSS removal rates between the measured and modeled values in model verification phase had a maximum difference of 11%. The results demonstrate that the proposed model is capable of capturing the temporal dynamics of the pavement performance. Therefore, the model has great potential as a practical modeling tool for permeable pavement design and performance assessment.
Savage, James; Pianosi, Francesca; Bates, Paul; Freer, Jim; Wagener, Thorsten
2015-04-01
Predicting flood inundation extents using hydraulic models is subject to a number of critical uncertainties. For a specific event, these uncertainties are known to have a large influence on model outputs and any subsequent analyses made by risk managers. Hydraulic modellers often approach such problems by applying uncertainty analysis techniques such as the Generalised Likelihood Uncertainty Estimation (GLUE) methodology. However, these methods do not allow one to attribute which source of uncertainty has the most influence on the various model outputs that inform flood risk decision making. Another issue facing modellers is the amount of computational resource that is available to spend on modelling flood inundations that are 'fit for purpose' to the modelling objectives. Therefore a balance needs to be struck between computation time, realism and spatial resolution, and effectively characterising the uncertainty spread of predictions (for example from boundary conditions and model parameterisations). However, it is not fully understood how much of an impact each factor has on model performance, for example how much influence changing the spatial resolution of a model has on inundation predictions in comparison to other uncertainties inherent in the modelling process. Furthermore, when resampling fine scale topographic data in the form of a Digital Elevation Model (DEM) to coarser resolutions, there are a number of possible coarser DEMs that can be produced. Deciding which DEM is then chosen to represent the surface elevations in the model could also influence model performance. In this study we model a flood event using the hydraulic model LISFLOOD-FP and apply Sobol' Sensitivity Analysis to estimate which input factor, among the uncertainty in model boundary conditions, uncertain model parameters, the spatial resolution of the DEM and the choice of resampled DEM, have the most influence on a range of model outputs. These outputs include whole domain maximum
Thermal-hydraulic modeling and analysis of spool valve with sloping U-shape notch by bond graph
Institute of Scientific and Technical Information of China (English)
娄磊; 吴万荣; 王兆强; 梁向京
2015-01-01
To increase the efficiency and reliability of the thermodynamics analysis of the spool valve, the precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke and thermal-hydraulic bond graph based on the conservation of mass and energy were introduced. Subsequently, the connection rule for the bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing the spool valve, the lumped parameter for mathematical model of the system was given. At last, the reliability of the mathematical model of the flow area and the thermal-hydraulic system for the sloping U-shape notch orifice on the spool were demonstrated by the test. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.
Directory of Open Access Journals (Sweden)
Li Yang
2017-01-01
Full Text Available Paste-like tailings slurry (PTLS is always simplified as a Bingham plastic fluid, leading to excessive computational errors in the calculation of the hydraulic gradient. In the case of paste-like tailings in long-distance pipeline transportation, to explore a high-precision and reliable hydraulic gradient formula, the rheological behavior of paste-like tailings slurry was analyzed, a time-varying hydraulic gradient model was constructed, and a series of laboratory shear tests were conducted. The results indicate that the PTLS shows noticeable shear-thinning characteristics in constant shear tests; the calculated hydraulic gradient declined by about 56%, from 4.44 MPa·km−1 to 1.95 MPa·km−1 within 253 s, and remained constant for the next four hours during the pipeline transportation. Comparing with the balance hydraulic gradient obtained in a semi-industrial loop test, the computational errors of those calculated by using the time-varying hydraulic gradient model, Jinchuan formula, and Shanxi formula are 15%, 78%, and 130%, respectively. Therefore, our model is a feasible and high-precision solution for the calculation of the hydraulic gradient of paste-like tailings in long-distance pipeline transportation.
Development of mathematical models for forecasting hydraulic loads of water and wastewater networks
Energy Technology Data Exchange (ETDEWEB)
Studzinki, Jan [Polish Academy of Sciences, Warsaw (Poland). Systems Research Institute; Bartkiewicz, Lidia [Technical Univ. Kielce (Poland); Stachura, Marcin [Warsaw University of Technology (Poland)
2013-07-01
In municipal waterworks the operation of water and wastewater networks decides about the functioning of the sewage treatment plant that is the last element of the whole water and sewage system. The both networks are connected each other and the work of the water net affects the operation of the wastewater one. The parameters which are important for right leading of all waterworks objects are their hydraulic loads that have to be not exceeded. Too large loads can cause accidents in the wastewater net or the treatment plant and an early knowledge of them is of importance for undertaking some counteractions. In the paper different algorithms to model hydraulic loads of municipal water and wastewater nets are described and compared regarding their computation velocity and accuracy. Some exemplary computations have been done with some real data received from a Polish water company. (orig.)
Neuville, Amélie; Schmittbuhl, Jean; 10.1111/j.1365-246X.2011.05126.x
2011-01-01
Natural open joints in rocks commonly present multi-scale self-affine apertures. This geometrical complexity affects fluid transport and heat exchange between the flow- ing fluid and the surrounding rock. In particular, long range correlations of self-affine apertures induce strong channeling of the flow which influences both mass and heat advection. A key question is to find a geometrical model of the complex aperture that describes at best the macroscopic properties (hydraulic conductivity, heat exchange) with the smallest number of parameters. Solving numerically the Stokes and heat equa- tions with a lubrication approximation, we show that a low pass filtering of the aperture geometry provides efficient estimates of the effective hydraulic and thermal properties (apertures). A detailed study of the influence of the bandwidth of the lowpass filtering on these transport properties is also performed. For instance, keeping the information of amplitude only of the largest Fourier length scales allows us to rea...
Micro-process model of hydraulic shock absorber with abnormal structural noise
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
In order to discover the causes of the abnormal noise of shock absorbers,it is necessary to identify the operating characteristics of the shock absorbers.A micro-process model for operation of the hydraulic shock absorber was presented.A novel concept,which describes the process of hydraulic shock absorber by dividing it into smaller steps,was proposed.The dynamic model and the differential equations were established.The results of numerical simulation agree well with data obtained from the vibrostand test,indicating that the collision between the piston and the oil,the alternation of static friction and sliding friction acted between the piston and the cylinder,and the adherence between valve plate and piston result in impact on the piston head near the top dead center and the bottom dead center.Ultimately,the impact excites the high-frequency vibration of the piston structure,which can generate the abnormal noise in the hydraulic shock absorber after its transfer.And the maximum vibration acceleration on the piston head and the abnormal noise increase with the increase of the gap between the oil and piston rod head,the maximum static friction force and the adhering function,respectively.
Low-field NMR logging sensor for measuring hydraulic parameters of model soils
Sucre, Oscar; Pohlmeier, Andreas; Minière, Adrien; Blümich, Bernhard
2011-08-01
SummaryKnowing the exact hydraulic parameters of soils is very important for improving water management in agriculture and for the refinement of climate models. Up to now, however, the investigation of such parameters has required applying two techniques simultaneously which is time-consuming and invasive. Thus, the objective of this current study is to present only one technique, i.e., a new non-invasive method to measure hydraulic parameters of model soils by using low-field nuclear magnetic resonance (NMR). Hereby, two model clay or sandy soils were respectively filled in a 2 m-long acetate column having an integrated PVC tube. After the soils were completely saturated with water, a low-field NMR sensor was moved up and down in the PVC tube to quantitatively measure along the whole column the initial water content of each soil sample. Thereafter, both columns were allowed to drain. Meanwhile, the NMR sensor was set at a certain depth to measure the water content of that soil slice. Once the hydraulic equilibrium was reached in each of the two columns, a final moisture profile was taken along the whole column. Three curves were subsequently generated accordingly: (1) the initial moisture profile, (2) the evolution curve of the moisture depletion at that particular depth, and (3) the final moisture profile. All three curves were then inverse analyzed using a MATLAB code over numerical data produced with the van Genuchten-Mualem model. Hereby, a set of values ( α, n, θr and θs) was found for the hydraulic parameters for the soils under research. Additionally, the complete decaying NMR signal could be analyzed through Inverse Laplace Transformation and averaged on the 1/ T2 space. Through measurement of the decay in pure water, the effect on the relaxation caused by the sample could be estimated from the obtained spectra. The migration of the sample-related average with decreasing saturation speaks for a enhancement of the surface relaxation as the soil dries, in
Wang, Chengwen; Quan, Long; Zhang, Shijie; Meng, Hongjun; Lan, Yuan
2017-03-01
Hydraulic servomechanism is the typical mechanical/hydraulic double-dynamics coupling system with the high stiffness control and mismatched uncertainties input problems, which hinder direct applications of many advanced control approaches in the hydraulic servo fields. In this paper, by introducing the singular value perturbation theory, the original double-dynamics coupling model of the hydraulic servomechanism was reduced to a integral chain system. So that, the popular ADRC (active disturbance rejection control) technology could be directly applied to the reduced system. In addition, the high stiffness control and mismatched uncertainties input problems are avoided. The validity of the simplified model is analyzed and proven theoretically. The standard linear ADRC algorithm is then developed based on the obtained reduced-order model. Extensive comparative co-simulations and experiments are carried out to illustrate the effectiveness of the proposed method.
Yan, Jun; Li, Bo; Guo, Gang; Zeng, Yonghua; Zhang, Meijun
2013-11-01
Electro-hydraulic control systems are nonlinear in nature and their mathematic models have unknown parameters. Existing research of modeling and identification of the electro-hydraulic control system is mainly based on theoretical state space model, and the parameters identification is hard due to its demand on internal states measurement. Moreover, there are also some hard-to-model nonlinearities in theoretical model, which needs to be overcome. Modeling and identification of the electro-hydraulic control system of an excavator arm based on block-oriented nonlinear(BONL) models is investigated. The nonlinear state space model of the system is built first, and field tests are carried out to reveal the nonlinear characteristics of the system. Based on the physic insight into the system, three BONL models are adopted to describe the highly nonlinear system. The Hammerstein model is composed of a two-segment polynomial nonlinearity followed by a linear dynamic subsystem. The Hammerstein-Wiener(H-W) model is represented by the Hammerstein model in cascade with another single polynomial nonlinearity. A novel Pseudo-Hammerstein-Wiener(P-H-W) model is developed by replacing the single polynomial of the H-W model by a non-smooth backlash function. The key term separation principle is applied to simplify the BONL models into linear-in-parameters structures. Then, a modified recursive least square algorithm(MRLSA) with iterative estimation of internal variables is developed to identify the all the parameters simultaneously. The identification results demonstrate that the BONL models with two-segment polynomial nonlinearities are able to capture the system behavior, and the P-H-W model has the best prediction accuracy. Comparison experiments show that the velocity prediction error of the P-H-W model is reduced by 14%, 30% and 75% to the H-W model, Hammerstein model, and extended auto-regressive (ARX) model, respectively. This research is helpful in controller design, system
Energy Technology Data Exchange (ETDEWEB)
Burton, Taylour G., E-mail: tgburton@uh.edu [Civil and Environmental Engineering, University of Houston, W455 Engineering Bldg. 2, Houston, TX 77204-4003 (United States); Rifai, Hanadi S., E-mail: rifai@uh.edu [Civil and Environmental Engineering, University of Houston, N138 Engineering Bldg. 1, Houston, TX 77204-4003 (United States); Hildenbrand, Zacariah L., E-mail: zac@informenv.com [Inform Environmental, LLC, Dallas, TX 75206 (United States); Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019 (United States); Carlton, Doug D., E-mail: doug.carlton@mavs.uta.edu [Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019 (United States); Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); Fontenot, Brian E., E-mail: brian.fonteno@mavs.uta.edu [Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019 (United States); Schug, Kevin A., E-mail: kschug@uta.edu [Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019 (United States); Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX (United States)
2016-03-01
Hydraulic fracturing operations have been viewed as the cause of certain environmental issues including groundwater contamination. The potential for hydraulic fracturing to induce contaminant pathways in groundwater is not well understood since gas wells are completed while isolating the water table and the gas-bearing reservoirs lay thousands of feet below the water table. Recent studies have attributed ground water contamination to poor well construction and leaks in the wellbore annulus due to ruptured wellbore casings. In this paper, a geospatial model of the Barnett Shale region was created using ArcGIS. The model was used for spatial analysis of groundwater quality data in order to determine if regional variations in groundwater quality, as indicated by various groundwater constituent concentrations, may be associated with the presence of hydraulically fractured gas wells in the region. The Barnett Shale reservoir pressure, completions data, and fracture treatment data were evaluated as predictors of groundwater quality change. Results indicated that elevated concentrations of certain groundwater constituents are likely related to natural gas production in the study area and that beryllium, in this formation, could be used as an indicator variable for evaluating fracturing impacts on regional groundwater quality. Results also indicated that gas well density and formation pressures correlate to change in regional water quality whereas proximity to gas wells, by itself, does not. The results also provided indirect evidence supporting the possibility that micro annular fissures serve as a pathway transporting fluids and chemicals from the fractured wellbore to the overlying groundwater aquifers. - Graphical abstract: A relative increase in beryllium concentrations in groundwater for the Barnett Shale region from 2001 to 2011 was visually correlated with the locations of gas wells in the region that have been hydraulically fractured over the same time period
Energy Technology Data Exchange (ETDEWEB)
Zhou, Jing [Universiyt of Utah; Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States); Deo, Milind
2015-10-01
The interaction between hydraulic fractures (HF) and natural fractures (NF) will lead to complex fracture networks due to the branching and merging of natural and hydraulic fractures in unconventional reservoirs. In this paper, a newly developed hydraulic fracturing simulator based on discrete element method is used to predict the generation of complex fracture network in the presence of pre-existing natural fractures. By coupling geomechanics and reservoir flow within a dual lattice system, this simulator can effectively capture the poro-elastic effects and fluid leakoff into the formation. When HFs are intercepting single or multiple NFs, complex mechanisms such as direct crossing, arresting, dilating and branching can be simulated. Based on the model, the effects of injected fluid rate and viscosity, the orientation and permeability of NFs and stress anisotropy on the HF-NF interaction process are investigated. Combined impacts from multiple parameters are also examined in the paper. The numerical results show that large values of stress anisotropy, intercepting angle, injection rate and viscosity will impede the opening of NFs.
Zhang, Zengmeng; Hou, Jiaoyi; Ning, Dayong; Gong, Xiaofeng; Gong, Yongjun
2017-05-01
Fluidic artificial muscles are popular in robotics and function as biomimetic actuators. Their pneumatic version has been widely investigated. A novel water hydraulic artificial muscle (WHAM) with high strength is developed in this study. WHAMs can be applied to underwater manipulators widely used in ocean development because of their environment-friendly characteristics, high force-to-weight ratio, and good bio-imitability. Therefore, the strength of WHAMs has been improved to fit the requirements of underwater environments and the work pressure of water hydraulic components. However, understanding the mechanical behaviors of WHAMs is necessary because WHAMs use work media and pressure control that are different from those used by pneumatic artificial muscles. This paper presents the static and dynamic characteristics of the WHAM system, including the water hydraulic pressure control circuit. A test system is designed and built to analyze the drive characteristics of the developed WHAM. The theoretical relationships among the amount of contraction, pressure, and output drawing force of the WHAM are tested and verified. A linearized transfer function is proposed, and the dynamic characteristics of the WHAM are investigated through simulation and inertia load experiments. Simulation results agree with the experimental results and show that the proposed model can be applied to the control of WHAM actuators.
Comparison of Measured and Modelled Hydraulic Conductivities of Fractured Sandstone Cores
Baraka-Lokmane, S.; Liedl, R.; Teutsch, G.
- A new method for characterising the detailed fracture geometry in sandstone cores is presented. This method is based on the impregnation of samples with coloured resin, without significant disturbance of the fractures. The fractures are made clearly visible by the resin, thus allowing the fracture geometry to be examined digitally. In order to model the bulk hydraulic conductivity, the samples are sectioned serially perpendicular to the flow direction. The hydraulic conductivity of individual sections is estimated by summing the contribution of the matrix and each fracture from the digital data. Finally, the hydraulic conductivity of the bulk sample is estimated by a harmonic average in series along the flow path. Results of this geometrical method are compared with actual physical conductivity values measured from fluid experiments carried out prior to sectioning. The predicted conductivity from the fracture geometry parameters (e.g., fracture aperture, fracture width, fracture length and fracture relative roughness all measured using an optical method) is in good agreement with the independent physical measurements, thereby validating the approach.
Institute of Scientific and Technical Information of China (English)
Yong-gang PENG; Jun WANG; Wei WEI
2014-01-01
In view of the high energy consumption and low response speed of the traditional hydraulic system for an injection molding machine, a servo motor driven constant pump hydraulic system is designed for a precision injection molding process, which uses a servo motor, a constant pump, and a pressure sensor, instead of a common motor, a constant pump, a pressure pro-portion valve, and a flow proportion valve. A model predictive control strategy based on neurodynamic optimization is proposed to control this new hydraulic system in the injection molding process. Simulation results showed that this control method has good control precision and quick response.
Hydraulic modelling for flood mapping and prevention: the case study of Cerfone River
Di Francesco, Silvia; Venturi, Sara; Manciola, Piergiorgio
2016-04-01
The research focuses on the hydraulic risk evaluation and danger estimation for different extreme flood events, in order to correctly implement mitigation measures in an anthropized basin. The Cerfone River (Tuscany, Italy), due to the several floods that have affected the neighbouring villages in recent years, is selected as case of study. A finite volume numerical model that solves the shallow water equations all over the computational domain, was used to simulate the unsteady evolution of the maximum extent of flooded areas for different scenarios. The one - dimensional approach (still widespread in engineering projects) can be inaccurate in complex flows, which are often two or three dimensional and sometimes does not manage to capture the flood spatial extents in terms of flow depth and velocity. The use of a two-dimensional numerical model seems to be the suitable instrument in terms of computational efficiency and adequacy of results. In fact it overcomes the limits of a one-dimensional modeling in terms of prediction of hydraulic variables with a less computational effort respect to a full 3d model. An accurate modeling of the river basin leads to the evaluation of the present hydraulic risk. Structural and non- structural measures are then studied, simulated and compared in order to define the optimal risk reduction plan for the area of study. At this aim, different flooding scenarios were simulated through the 2D mathematical model: i) existing state of the river and floodplain areas; ii) design of a levee to protect the most vulnerable populated areas against the flooding risk; iii) use of off - stream detention basins that strongly amplify the lamination capacity of floodplains. All these scenarios were simulated for different return periods: 50, 100, 200 and 500 years. The inputs of the hydraulic models are obtained in accordance with the legislative requirement of Tuscany Region; in particular discharge hydrographs are evaluate through the ALTo
Subchannel thermal-hydraulic modeling of an APT tungsten target rod bundle
Energy Technology Data Exchange (ETDEWEB)
Hamm, L.L.; Shadday, M.A. Jr.
1997-09-01
The planned target for the Accelerator Production of Tritium (APT) neutron source consists of an array of tungsten rod bundles through which D{sub 2}O coolant flows axially. Here, a scoping analysis of flow through an APT target rod bundle was conducted to demonstrate that lateral cross-flows are important, and therefore subchannel modeling is necessary to accurately predict thermal-hydraulic behavior under boiling conditions. A local reactor assembly code, FLOWTRAN, was modified to model axial flow along the rod bundle as flow through three concentric heated annular passages.
Directory of Open Access Journals (Sweden)
Vahdettin Demir
2016-01-01
Full Text Available In this study, flood hazard maps were prepared for the Mert River Basin, Samsun, Turkey, by using GIS and Hydrologic Engineering Centers River Analysis System (HEC-RAS. In this river basin, human life losses and a significant amount of property damages were experienced in 2012 flood. The preparation of flood risk maps employed in the study includes the following steps: (1 digitization of topographical data and preparation of digital elevation model using ArcGIS, (2 simulation of flood lows of different return periods using a hydraulic model (HEC-RAS, and (3 preparation of flood risk maps by integrating the results of (1 and (2.
Directory of Open Access Journals (Sweden)
N.V. Arefyev
2013-10-01
Full Text Available Currently, there is an increase of diversity in the design of complex hydraulic structures. Thus there is a need to establish adequate mathematical models and software with complete description of processes. These models should be focused on certain classes of problems, which statements may change during the simulation. So, in our opinion, so-called self-organizing simulation models are perspective, they adapt to changes in the operating practice of the objects that require rapid adjustments in the boundary conditions and the field of simulation. Results of development of self-adapting complexes of numerical models, permitting calculation of complex water passageway systems with varying flow regime on separate parts (discharge; movement on the dry bottom, provided hydraulic head in free-flow downstream tunnel etc.. Presented system traces the movement of modeling area boundaries (when filling and dumping water passage sections and chooses the appropriate boundary condition with changing flow regime on the border of modelling area of the flow (free-flowing weir – drowned weir.Given results of numerical simulation of real systems make it possible to consider proposed approach as efficient.
Fredette, Luke; Dreyer, Jason T.; Rook, Todd E.; Singh, Rajendra
2016-06-01
The dynamic stiffness properties of automotive hydraulic bushings exhibit significant amplitude sensitivity which cannot be captured by linear time-invariant models. Quasi-linear and nonlinear models are therefore proposed with focus on the amplitude sensitivity in magnitude and loss angle spectra (up to 50 Hz). Since production bushing model parameters are unknown, dynamic stiffness tests and laboratory experiments are utilized to extract model parameters. Nonlinear compliance and resistance elements are incorporated, including their interactions in order to improve amplitude sensitive predictions. New solution approximations for the new nonlinear system equations refine the multi-term harmonic balance term method. Quasi-linear models yield excellent accuracy but cannot predict trends in amplitude sensitivity since they rely on available dynamic stiffness measurements. Nonlinear models containing both nonlinear resistance and compliance elements yield superior predictions to those of prior models (with a single nonlinearity) while also providing more physical insight. Suggestion for further work is briefly mentioned.
Energy Technology Data Exchange (ETDEWEB)
Rutqvist, Jonny; Rinaldi, Antonio P.; Cappa, Frédéric; Moridis, George J.
2013-07-01
We have conducted numerical simulation studies to assess the potential for injection-induced fault reactivation and notable seismic events associated with shale-gas hydraulic fracturing operations. The modeling is generally tuned towards conditions usually encountered in the Marcellus shale play in the Northeastern US at an approximate depth of 1500 m (~;;4,500 feet). Our modeling simulations indicate that when faults are present, micro-seismic events are possible, the magnitude of which is somewhat larger than the one associated with micro-seismic events originating from regular hydraulic fracturing because of the larger surface area that is available for rupture. The results of our simulations indicated fault rupture lengths of about 10 to 20 m, which, in rare cases can extend to over 100 m, depending on the fault permeability, the in situ stress field, and the fault strength properties. In addition to a single event rupture length of 10 to 20 m, repeated events and aseismic slip amounted to a total rupture length of 50 m, along with a shear offset displacement of less than 0.01 m. This indicates that the possibility of hydraulically induced fractures at great depth (thousands of meters) causing activation of faults and creation of a new flow path that can reach shallow groundwater resources (or even the surface) is remote. The expected low permeability of faults in producible shale is clearly a limiting factor for the possible rupture length and seismic magnitude. In fact, for a fault that is initially nearly-impermeable, the only possibility of larger fault slip event would be opening by hydraulic fracturing; this would allow pressure to penetrate the matrix along the fault and to reduce the frictional strength over a sufficiently large fault surface patch. However, our simulation results show that if the fault is initially impermeable, hydraulic fracturing along the fault results in numerous small micro-seismic events along with the propagation, effectively
Zeng, Ming; Soric, Audrey; Roche, Nicolas
2013-09-01
In this study, total organic carbon (TOC) biodegradation was simulated by GPS-X software in biofilm reactors with carriers of plastic rings and glass beads under different hydraulic conditions. Hydrodynamic model by retention time distribution and biokinetic measurement by in-situ batch test served as two significant parts of model calibration. Experimental results showed that TOC removal efficiency was stable in both media due to the enough height of column, although the actual hydraulic volume changed during the variation of hydraulic condition. Simulated TOC removal efficiencies were close to experimental ones with low theil inequality coefficient values (below 0.15). Compared with glass beads, more TOC was removed in the filter with plastic rings due to the larger actual hydraulic volume and lower half saturation coefficient in spite of its lower maximum specific growth rate of biofilm, which highlighted the importance of calibrating hydrodynamic behavior and biokinetics.
The hydraulic jump in radially spreading flow: A new model and new experimental data
Blackford, B. L.
1996-02-01
A new model for the hydraulic jump in radially spreading flow is presented. The equation of motion for a liquid annulus spreading out under the influence of hydrostatic pressure gradient and Frictional drag is developed. The resulting nonlinear differential equation for the liquid depth, h(r), is solved by computer simulation. The jump is assumed to begin when the laminar flow is engulfed by the underlying boundary layer liquid, as suggested recently in the literature. This complicated mixing process is crudely modeled by a drag term which slows the flow and initiates a positive feedback mechanism culminating at a new critical depth, beyond which the depth increases asymptotically to a final value. The model predicts a new relationship between the laminar flow depth just before the jump and the final depth. An experimental apparatus was built to make detailed measurements of the depth h(r), both in the region before the jump and beyond the jump. The theoretical predictions were compared to the experimental data, and gave surprisingly good agreement by suitable adjustment of the two parameters k and C of the model. The parameter k determines the growth rate of the boundary layer thickness, and C determines the drag force. The results suggest that the usual textbook assumption of zero momentum loss across the jump is not appropriate for this type of hydraulic jump. The case of a hydraulic jump in the absence of gravity is considered also and a much different behavior is predicted, which could be tested by experiment in a microgravity environment.
Growth model for large branched three-dimensional hydraulic crack system in gas or oil shale.
Chau, Viet T; Bažant, Zdeněk P; Su, Yewang
2016-10-13
Recent analysis of gas outflow histories at wellheads shows that the hydraulic crack spacing must be of the order of 0.1 m (rather than 1 m or 10 m). Consequently, the existing models, limited to one or several cracks, are unrealistic. The reality is 10(5)-10(6) almost vertical hydraulic cracks per fracking stage. Here, we study the growth of two intersecting near-orthogonal systems of parallel hydraulic cracks spaced at 0.1 m, preferably following pre-existing rock joints. One key idea is that, to model lateral cracks branching from a primary crack wall, crack pressurization, by viscous Poiseuille-type flow, of compressible (proppant-laden) frac water must be complemented with the pressurization of a sufficient volume of micropores and microcracks by Darcy-type water diffusion into the shale, to generate tension along existing crack walls, overcoming the strength limit of the cohesive-crack or crack-band model. A second key idea is that enforcing the equilibrium of stresses in cracks, pores and water, with the generation of tension in the solid phase, requires a new three-phase medium concept, which is transitional between Biot's two-phase medium and Terzaghi's effective stress and introduces the loading of the solid by pressure gradients of diffusing pore water. A computer program, combining finite elements for deformation and fracture with volume elements for water flow, is developed to validate the new model.This article is part of the themed issue 'Energy and the subsurface'.
Christoffersen, Bradley O.; Gloor, Manuel; Fauset, Sophie; Fyllas, Nikolaos M.; Galbraith, David R.; Baker, Timothy R.; Kruijt, Bart; Rowland, Lucy; Fisher, Rosie A.; Binks, Oliver J.; Sevanto, Sanna; Xu, Chonggang; Jansen, Steven; Choat, Brendan; Mencuccini, Maurizio; McDowell, Nate G.; Meir, Patrick
2016-11-01
Forest ecosystem models based on heuristic water stress functions poorly predict tropical forest response to drought partly because they do not capture the diversity of hydraulic traits (including variation in tree size) observed in tropical forests. We developed a continuous porous media approach to modeling plant hydraulics in which all parameters of the constitutive equations are biologically interpretable and measurable plant hydraulic traits (e.g., turgor loss point πtlp, bulk elastic modulus ɛ, hydraulic capacitance Cft, xylem hydraulic conductivity ks,max, water potential at 50 % loss of conductivity for both xylem (P50,x) and stomata (P50,gs), and the leaf : sapwood area ratio Al : As). We embedded this plant hydraulics model within a trait forest simulator (TFS) that models light environments of individual trees and their upper boundary conditions (transpiration), as well as providing a means for parameterizing variation in hydraulic traits among individuals. We synthesized literature and existing databases to parameterize all hydraulic traits as a function of stem and leaf traits, including wood density (WD), leaf mass per area (LMA), and photosynthetic capacity (Amax), and evaluated the coupled model (called TFS v.1-Hydro) predictions, against observed diurnal and seasonal variability in stem and leaf water potential as well as stand-scaled sap flux. Our hydraulic trait synthesis revealed coordination among leaf and xylem hydraulic traits and statistically significant relationships of most hydraulic traits with more easily measured plant traits. Using the most informative empirical trait-trait relationships derived from this synthesis, TFS v.1-Hydro successfully captured individual variation in leaf and stem water potential due to increasing tree size and light environment, with model representation of hydraulic architecture and plant traits exerting primary and secondary controls, respectively, on the fidelity of model predictions. The plant
Modelling, Testing and Analysis of a Regenerative Hydraulic Shock Absorber System
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Ruichen Wang
2016-05-01
Full Text Available To improve vehicle fuel economy whilst enhancing road handling and ride comfort, power generating suspension systems have recently attracted increased attention in automotive engineering. This paper presents our study of a regenerative hydraulic shock absorber system which converts the oscillatory motion of a vehicle suspension into unidirectional rotary motion of a generator. Firstly a model which takes into account the influences of the dynamics of hydraulic flow, rotational motion and power regeneration is developed. Thereafter the model parameters of fluid bulk modulus, motor efficiencies, viscous friction torque, and voltage and torque constant coefficients are determined based on modelling and experimental studies of a prototype system. The model is then validated under different input excitations and load resistances, obtaining results which show good agreement between prediction and measurement. In particular, the system using piston-rod dimensions of 50–30 mm achieves recoverable power of 260 W with an efficiency of around 40% under sinusoidal excitation of 1 Hz frequency and 25 mm amplitude when the accumulator capacity is set to 0.32 L with the load resistance 20 Ω. It is then shown that the appropriate damping characteristics required from a shock absorber in a heavy-haulage vehicle can be met by using variable load resistances and accumulator capacities in a device akin to the prototype. The validated model paves the way for further system optimisation towards maximising the performance of regeneration, ride comfort and handling.
A void ratio dependent water retention curve model including hydraulic hysteresis
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Pasha Amin Y.
2016-01-01
Full Text Available Past experimental evidence has shown that Water Retention Curve (WRC evolves with mechanical stress and structural changes in soil matrix. Models currently available in the literature for capturing the volume change dependency of WRC are mainly empirical in nature requiring an extensive experimental programme for parameter identification which renders them unsuitable for practical applications. In this paper, an analytical model for the evaluation of the void ratio dependency of WRC in deformable porous media is presented. The approach proposed enables quantification of the dependency of WRC on void ratio solely based on the form of WRC at the reference void ratio and requires no additional parameters. The effect of hydraulic hysteresis on the evolution process is also incorporated in the model, an aspect rarely addressed in the literature. Expressions are presented for the evolution of main and scanning curves due to loading and change in the hydraulic path from scanning to main wetting/drying and vice versa as well as the WRC parameters such as air entry value, air expulsion value, pore size distribution index and slope of the scanning curve. The model is validated using experimental data on compacted and reconstituted soils subjected to various hydro-mechanical paths. Good agreement is obtained between model predictions and experimental data in all the cases considered.
Development of the Real-time Core and Thermal-Hydraulic Models for Kori-1 Simulator
Energy Technology Data Exchange (ETDEWEB)
Hong, Jin Hyuk; Lee, Myeong Soo; Hwang, Do Hyun; Byon, Soo Jin [KEPRI, Daejeon (Korea, Republic of)
2010-10-15
The operation of the Kori-Unit 1 (1723.5MWt) is expanded to additional 10 years with upgrades of the Main Control Room (MCR). Therefore, the revision of the procedures, performance tests and works related with the exchange of the Main Control Board (MCB) are currently carried out. And as a part of it, the fullscope simulator for the Kori-1 is being developed for the purpose of the pre-operation and emergence response capability for the operators. The purpose of this paper is to report on the performance of the developed neutronics and thermal-hydraulic (TH) models of Kori Unit 1 simulator. The neutronics model is based on the NESTLE code and TH model based on the RELAP5/MOD3 thermal-hydraulics analysis code which was funded as FY-93 LDRD Project 7201 and is running on the commercial simulator environment tool (the 3KeyMaster{sup TM} of the WSC). As some examples for the verification of the developed neutronics and TH models, some figures are provided. The outputs of the developed neutronics and TH models are in accord with the Nuclear Design Report (NDR) and Final Safety Analysis Report (FSAR) of the reference plant
Modelling the Hydraulic Behaviour of Growing Media with the Explicit Finite Volume Solution
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Marco Carbone
2015-02-01
Full Text Available The increasing imperviousness of urban areas reduces the infiltration and evapotranspiration capacity of urban catchments and results in increased runoff. In the last few decades, several solutions and techniques have been proposed to prevent such impacts by restoring the hydrological cycle. A limiting factor in spreading the use of such systems is the lack of proper modelling tools for design, especially for the infiltration processes in a growing medium. In this research, a physically-based model, employing the explicit Finite Volume Method (FVM, is proposed for modelling infiltration into growing media. The model solves a modified version of the Richards equation using a formulation which takes into account the main characteristics of green infrastructure substrates. The proposed model was verified against the HYDRUS-1D software and the comparison of results confirmed the suitability of the proposed model for correctly describing the hydraulic behaviour of soil substrates.
Flower, a Model for the Analysis of Hydraulic Networks and Processes
Bottura, L
2003-01-01
We have developed in the past years a model that describes hydraulic networks that are typical of the cryogenic interconnection of superconducting magnets. The original model, called Flower, was used mostly to provide consistent boundary conditions for the operation of a magnet. The main limitations were associated with the number and nature of modelling elements available, and to the maximum size of the model that could be solved. Here we present an improvement of the model largely relaxing the above limitations by the addition of new modelling elements, such as parallel flow heat exchangers, and by a significant improvement in the numerics of the solver, using sparse matrix storage and solution techniques. We finally show a typical application to the case of a magnet quench in the LHC string.
Modelling Hydraulic and Thermal Responses in a Benchmark for Deep Geothermal Heat Production
Holzbecher, E.; Oberdorfer, P.
2012-04-01
Geothermal heat production from deep reservoirs (5000-7000 m) is currently examined within the collaborative research program "Geothermal Energy and High-Performance Drilling" (gebo), funded by the Ministry of Science and Culture of Lower Saxony (Germany) and Baker Hughes. The projects concern exploration and characterization of geothermal reservoirs as well as production. They are gathered in the four major topic fields: geosystem, drilling, materials, technical system. We present modelling of a benchmark set-up concerning the geothermal production itself. The benchmark model "Horstberg" was originally created by J. Löhken and is based on geological data, concerning the Horstberg site in Lower Saxony. The model region consists of a cube with a side length of 5 km, in which 13 geological layers are included. A fault zone splits the region into two parts with shifted layering. A well is implemented, reaching from the top to an optional depth crossing all layers including the fault zone. The original geological model was rebuilt and improved in COMSOL Multiphysics Version 4.2a. The heterogeneous and detailed configuration makes the model interesting for benchmarking hydrogeological and geothermal applications. It is possible to inject and pump at any level in the well and to study the hydraulic and thermal responses of the system. The hydraulic and thermal parameters can be varied, and groundwater flow can be introduced. Moreover, it is also possible to examine structural mechanical responses to changes in the stress field (which is not further examined here). The main purpose of the presented study is to examine the dynamical flow characteristics of a hydraulic high conductive zone (Detfurth) in connection to a high conductive fault. One example is the fluid injection in the Detfurth zone and production in the fault. The high conductive domains can provide a hydraulic connection between the well screens and the initiated flow circuit could be used for geothermal
Modeling and Control of a teletruck using electronic load sensing
DEFF Research Database (Denmark)
Hansen, Rico Hjerm; Iversen, Asger Malte; Jensen, Mads Schmidt;
2010-01-01
system is most commonly controlled using a hydro-mechanical control scheme called Hydraulic Load Sensing (HLS). However, with the demands for increased efficiency and controllability the HLS solutions are reaching their limits. Motivated by availability of electronic controllable fluid power...... the controller design for the ELS system, a complete model of the teletruck’s articulated arm and fluid power system is developed. To show the feasibility, a preliminary control structure for the ELS system is developed. The controller is tested on the machine, validating that features such as pump pressure...
The role of 3D-hydraulics in habitat modelling of hydropeaking events.
Pisaturo, Giuseppe Roberto; Righetti, Maurizio; Dumbser, Michael; Noack, Markus; Schneider, Matthias; Cavedon, Valentina
2017-01-01
One way to study ecological implications induced by hydropeaking represents the coupling of hydrodynamic models with habitat suitability models, in which hydrodynamic parameters are typically used to describe the physical habitat of indicator species. This article discusses the differences in habitat suitability assessment between 2D and 3D CFD modelling as input for the habitat simulation tool CASiMiR. In the first part of the article, the accuracy of the hydraulic model is evaluated by comparing the model results with laboratory (model of a laboratory channel with erodible bed) and field measurements (Valsura River, Bolzano, Italy). In the second part, the habitat suitability for the Valsura River case study (affected by hydropeaking), is analyzed comparing different approaches for the reconstruction of the velocity field (depth-averaged velocities from 2D modelling, bottom velocity field reconstruction with log-law approach from 2D modelling and bottom velocity field from 3D modelling). The results show that the habitat suitability index (HSI) using 2D or 3D hydrodynamic models can be significantly different. These differences can be ascribed to a higher capability to depict the features of the flow field with highly variable and heterogeneous boundary conditions and to the possibility to simulate the near bed hydrodynamic parameters, which are relevant for certain target species. In particular, the HSI-values using 3D hydraulics lead to larger areas of highly suitable habitats compared to 2D simulations. Moreover, considering the entire flow range of hydropeaking events, the habitat simulations with bottom flow velocities from 3D modelling provide suitable habitats over the entire flow range representing the availability of stable suitable habitats, while the habitat availability of 2D modelled flow velocity is continuously decreasing with increasing flow rates. Copyright © 2016 Elsevier B.V. All rights reserved.
Institute of Scientific and Technical Information of China (English)
SUNG Wen-Pei; SHIH Ming-Hsiang
2008-01-01
A passive energy-dissipating device,velocity,and displacement dependent hydraulic damper (VDHD),is developed to reduce the seismic response of structure.This device is cemprised of a hydraulic jack,check valve,relief valve,and throttle valve.The numerical analysis model for SAP2000 nonlinear analysis program is proposed to simulate the energy-dissipating characteristics of VDHD.The analysis re-sults of this model compared with the seismic resistant tests reveal that this proposed model can accurately describe the actual energy-dissipating behavior of VDHD.The efficiency of VDHD is confirmed using this proposed model for carrying out numerical analyses of bare building,building added with bulking resistant bracing(BBR),and VDHD.The energy-dissipating capabilities of VDHD are performing excellent displace-ment and acceleration control with various ground magnitudes;being an energy absorber to absorb me-chanical energy in the structure and resist structural movement;and gathering the advantage of BRB.
Models for Gas Hydrate-Bearing Sediments Inferred from Hydraulic Permeability and Elastic Velocities
Lee, Myung W.
2008-01-01
Elastic velocities and hydraulic permeability of gas hydrate-bearing sediments strongly depend on how gas hydrate accumulates in pore spaces and various gas hydrate accumulation models are proposed to predict physical property changes due to gas hydrate concentrations. Elastic velocities and permeability predicted from a cementation model differ noticeably from those from a pore-filling model. A nuclear magnetic resonance (NMR) log provides in-situ water-filled porosity and hydraulic permeability of gas hydrate-bearing sediments. To test the two competing models, the NMR log along with conventional logs such as velocity and resistivity logs acquired at the Mallik 5L-38 well, Mackenzie Delta, Canada, were analyzed. When the clay content is less than about 12 percent, the NMR porosity is 'accurate' and the gas hydrate concentrations from the NMR log are comparable to those estimated from an electrical resistivity log. The variation of elastic velocities and relative permeability with respect to the gas hydrate concentration indicates that the dominant effect of gas hydrate in the pore space is the pore-filling characteristic.
Rodríguez-Escales, Paula; Folch, Albert; van Breukelen, Boris; Vidal-Gavilan, Georgina; Sanchez-Vila, Xavier
2015-04-01
We developed a reactive transport model that reproduced a 342 days long laboratory column experiment of biodenitrification processes with different injection strategies in terms of frequency (daily, weekly) and C:N ratio. Furthermore, we evaluated changes in hydraulic properties as result of biodenitrification. It was found that biodenitrification promoted the transition from normal to anomalous (non-Fickian) transport due to the increase of heterogeneity in hydraulic parameters. Comparing the breakthrough curves from two conservative bromide tracer tests performed at the beginning and at the end of the experiment, two significant features were observed: first, an increase in dispersivity, and second, a transition from a curve that can be modeled with an advection-dispersion equation to a different one that can be modeled using a dual domain mass transfer model. This behavior is associated to the presence of a diffusive layer promoted by biofilm growth during the last 100 days of the experiment. Regarding the injection conditions, it was found that besides other parameters described in the literature (nutrient loading, flow rate, and grain size), injection frequency significantly modifies dispersivity, being largest for continuous injection. Moreover, reducing the C:N ratio for optimizing costs was possible after a substantial biomass developed. A careful design of injection conditions and substrate rates can then be devised in specific cases to promote biodenitrification.
Modeling and analysis of a meso-hydraulic climbing robot with artificial muscle actuation.
Chapman, Edward M; Jenkins, Tyler E; Bryant, Matthew
2017-07-10
This paper presents a fully coupled electro-hydraulic model of a bio-inspired climbing robot actuated by fluidic artificial muscles (FAMs). This analysis expands upon previous FAM literature by considering not only the force and contraction characteristics of the actuator, but the complete hydraulic and electromechanical circuits as well as the dynamics of the climbing robot. This analysis allows modeling of the time-varying applied pressure, electrical current, and actuator contraction for accurate prediction of the robot motion, energy consumption, and mechanical work output. The developed model is first validated against mechanical and electrical data collected from a proof-of-concept prototype robot. The model is then employed to study the system-level sensitivities of the robot locomotion efficiency and average climbing speed to several design and operating parameters. The results of this analysis demonstrate that considering only the transduction efficiency of the FAM actuators is insufficient to maximize the efficiency of the complete robot, and that a holistic approach can lead to significant improvements in performance. © 2017 IOP Publishing Ltd.
Directory of Open Access Journals (Sweden)
V. Couvreur
2012-08-01
Full Text Available Many hydrological models including root water uptake (RWU do not consider the dimension of root system hydraulic architecture (HA because explicitly solving water flow in such a complex system is too time consuming. However, they might lack process understanding when basing RWU and plant water stress predictions on functions of variables such as the root length density distribution. On the basis of analytical solutions of water flow in a simple HA, we developed an "implicit" model of the root system HA for simulation of RWU distribution (sink term of Richards' equation and plant water stress in three-dimensional soil water flow models. The new model has three macroscopic parameters defined at the soil element scale, or at the plant scale, rather than for each segment of the root system architecture: the standard sink fraction distribution SSF, the root system equivalent conductance K_{rs} and the compensatory RWU conductance K_{comp}. It clearly decouples the process of water stress from compensatory RWU, and its structure is appropriate for hydraulic lift simulation. As compared to a model explicitly solving water flow in a realistic maize root system HA, the implicit model showed to be accurate for predicting RWU distribution and plant collar water potential, with one single set of parameters, in dissimilar water dynamics scenarios. For these scenarios, the computing time of the implicit model was a factor 28 to 214 shorter than that of the explicit one. We also provide a new expression for the effective soil water potential sensed by plants in soils with a heterogeneous water potential distribution, which emerged from the implicit model equations. With the proposed implicit model of the root system HA, new concepts are brought which open avenues towards simple and mechanistic RWU models and water stress functions operational for field scale water dynamics simulation.
Directory of Open Access Journals (Sweden)
V. Couvreur
2012-04-01
Full Text Available Many hydrological models including root water uptake (RWU do not consider the dimension of root system hydraulic architecture (HA because explicitly solving water flow in such a complex system is too much time consuming. However, they might lack process understanding when basing RWU and plant water stress predictions on functions of variables such as the root length density distribution. On the basis of analytical solutions of water flow in a simple HA, we developed an "implicit" model of the root system HA for simulation of RWU distribution (sink term of Richards' equation and plant water stress in three-dimensional soil water flow models. The new model has three macroscopic parameters defined at the soil element scale or at the plant scale rather than for each segment of the root architecture: the standard sink distribution SSD, the root system equivalent conductance K_{rs} and the compensatory conductance K_{comp}. It clearly decouples the process of water stress from compensatory RWU and its structure is appropriate for hydraulic lift simulation. As compared to a model explicitly solving water flow in a realistic maize root system HA, the implicit model showed to be accurate for predicting RWU distribution and plant collar water potential, with one single set of parameters, in contrasted water dynamics scenarios. For these scenarios, the computing time of the implicit model was a factor 28 to 214 shorter than that of the explicit one. We also provide a new expression for the effective soil water potential sensed by plants in soils with a heterogeneous water potential distribution, which emerged from the implicit model equations. With the proposed implicit model of the root system HA, new concepts are brought which open avenues towards simple and process understanding RWU models and water stress functions operational for field scale water dynamics simulation.
Li, Yuwei; Jia, Dan; Wang, Meng; Liu, Jia; Fu, Chunkai; Yang, Xinliang; Ai, Chi
2016-08-01
In developing internal fracture systems in coal beds, the initiation mechanism differs greatly from that of conventional ones and initiations may be produced beyond the wellbore wall. This paper describes the features of the internal structure of coal beds and RFPA2D simulation is used to attest the possible occurrence of initiation beyond the wellbore wall in coal bed hydraulic fracturing. Using the theory of elasticity and fracture mechanics, we analyse the stress distribution in the vicinal coal rock. Then by taking into consideration the effects of the spatial relationship between coal bed cleats and the wellbore, we establish a model for calculating both tensile and shear initiation pressure that occur along cleats beyond the wellbore wall. The simulation in this paper indicates that for shear initiations that happen along coal cleats, the pressure required to initiate fracture for cleats beyond the wellbore wall is evidently lower than that on the wellbore wall, thus it is easier to initiate shear fractures for cleats beyond the wellbore wall. For tensile failure, the pressure required to initiate tensile fracture for cleats beyond the wellbore wall is obviously higher than that for cleats at the wellbore wall, thus it is easier to initiate tensile fractures for cleats at the wellbore wall. On the one hand, this paper has proved the possible occurrence of initiations beyond the wellbore wall and has changed the current assumption that hydraulic fractures can only occur at the wellbore wall. On the other hand, the established theoretical model provides a new approach to calculating the initiation pressure in hydraulic fracturing.
Rounce, D.; McKinney, D. C.
2015-12-01
The last half century has witnessed considerable glacier melt that has led to the formation of large glacial lakes. These glacial lakes typically form behind terminal moraines comprising loose boulders, debris, and soil, which are susceptible to fail and cause a glacial lake outburst flood (GLOF). These lakes also act as a heat sink that accelerates glacier melt and in many cases is accompanied by rapid areal expansion. As these glacial lakes continue to grow, their hazard also increases due to the increase in potential flood volume and the lakes' proximity to triggering events such as avalanches and landslides. Despite the large threat these lakes may pose to downstream communities, there are few detailed studies that combine satellite imagery with hydraulic models to present a holistic understanding of the GLOF hazard. The aim of this work is to assess the GLOF hazard of glacial lakes in Nepal using a holistic approach based on a combination of satellite imagery and hydraulic models. Imja Lake will be the primary focus of the modeling efforts, but the methods will be developed in a manner that is transferable to other potentially dangerous glacial lakes in Nepal.
Zhong, Xiao; Sun, Peide; Song, Yingqi; Wang, Ruyi; Fang, Zhiguo
2010-11-01
Based on the fully coupled activated sludge model (FCASM), the novel model Tubificidae -Fully Coupled Activated Sludge Model-hydraulic (T-FCASM-Hydro), has been developed in our previous work. T-FCASM-Hydro not only describe the interactive system between Tubificidae and functional microorganisms for the sludge reduction and nutrient removal simultaneously, but also considere the interaction between biological and hydraulic field, After calibration and validation of T-FCASM-Hydro at Zhuji Feida-hongyu Wastewater treatment plant (WWTP) in Zhejiang province, T-FCASM-Hydro was applied for determining optimal operating condition in the WWTP. Simulation results showed that nitrogen and phosphorus could be removed efficiently, and the efficiency of NH4+-N removal enhanced with increase of DO concentration. At a certain low level of DO concentration in the aerobic stage, shortcut nitrification-denitrification dominated in the process of denitrification in the novel system. However, overhigh agitation (>6 mgṡL-1) could result in the unfavorable feeding behavior of Tubificidae because of the strong flow disturbance, which might lead to low rate of sludge reduction. High sludge reduction rate and high removal rate of nitrogen and phosphorus could be obtained in the new-style oxidation ditch when DO concentration at the aerobic stage with Tubificidae was maintained at 3.6 gṡm-3.
Xiao, Boqi; Tu, Xing; Ren, Wen; Wang, Zongchi
2015-06-01
In this study, the analytical expressions for the hydraulic permeability and Kozeny-Carman (KC) constant of porous nanofibers are derived based on fractal theory. In the present approach, the permeability is explicitly related to the porosity and the area fractal dimensions of porous nanofibers. The proposed fractal models for KC constant is also found to be a function of the microstructural parameters (porosity, area fractal dimensions). Besides, the present model clearly indicates that KC constant is not a constant and increases with porosity. However, KC constant is close to a constant value which is 18 for ϕ > 0.8. Every parameter of the proposed formulas of calculating permeability and KC constant has clear physical meaning. The model predictions are compared with the existing experimental data, and fair agreement between the model predictions and experimental data is found for different porosities.
MODEL TESTS OF HYDRAULIC FLOW CONDITIONS IN THE VEGETATION BUILD-UP FISHWAY
Directory of Open Access Journals (Sweden)
Tomasz Tymiński
2015-10-01
Full Text Available Our engineering activity aiming at keeping ecological corridors in rivers are a difficult and complex issue that requires specialist knowledge in many disciplines. One of the installations for ensuring ecological continuum river are fishways, particularly their “near-natural” designs. They resemble mountain streams and creeks. Natural materials, such as wood, vegetation, gravel, stones and rocks are used for their construction. Design of hydraulic fishways based solely on the criteria of maximum speed vmax and parameter of unitary energy of water E, it does not give complete information about the effectiveness of these devices. In order to produce the optimal flow conditions for ichthyofauna, very useful are spatial structure research of hydraulic parameters, such as disorders of flow velocity field or distributions of the turbulence number Tu. The article presents an example of such a study, which the authors carried out on the model seminatural fishway in the water laboratory in Institute of Environmental Engineering in Wrocław. The results were used to assess the accuracy of the functioning of the fishway. The tested combination of “vegetated baffles” and “pools” in the fishway model was found to be optimal for the ichthyofauna. Vegetation build-up in fishways is an interesting and proecological alternative for “heavy” technical build-up.
Estimating the Hydraulic Properties of Mountainous Podzol Soils Using Inverse Modeling Methods
Kuraz, Michal; Jacka, Lukas; Havlicek, Vojtech; Pavlasek, Jirka; Pech, Pavel
2016-04-01
The aim of this research is an evaluation of the soil hydraulic parameters (SHP) for a mountainous podzolic soil profile. The SHPs for the lower layers can be identified using standard approaches - a single ring (SR) infiltration experiment and a Guelph permeameter (GP) measurement. However, the thickness of the top soil layer is often much lower than the depth required to embed an SR or GP device, and the SHP for the top soil layer exhibits large temporal and spatial changes due to changes in vegetation activity during the seasons and a distinct alternation of wetting and drying cycles. SHPs for the top soil layer are therefore very difficult to measure directly. The SHPs for the top soil layer were therefore identified here by inverse modeling of the SR infiltration process, where, especially, the initial unsteady part of the experiment can provide very useful data for evaluating the retention curve parameters and the saturated hydraulic conductivity. This inverse analysis is the main topic of this paper. We discuss issues in assigning the initial and boundary condition setup, and the influence of spatial and temporal discretization on the values of the identified SHPs. Since the infiltration process is a typical case of a model that describes the progressive breakthrough of the wetting curve, we made use of adaptive domain decomposition (dd-adaptivity) described by Kuraz et al. (2013, 2014, 2015) for sequential activation and deactivation of the segments of our computational domain. Finally, we conducted a sensitivity analysis of our objective function on the SHP set.
Modular GIS Framework for National Scale Hydrologic and Hydraulic Modeling Support
Djokic, D.; Noman, N.; Kopp, S.
2015-12-01
Geographic information systems (GIS) have been extensively used for pre- and post-processing of hydrologic and hydraulic models at multiple scales. An extensible GIS-based framework was developed for characterization of drainage systems (stream networks, catchments, floodplain characteristics) and model integration. The framework is implemented as a set of free, open source, Python tools and builds on core ArcGIS functionality and uses geoprocessing capabilities to ensure extensibility. Utilization of COTS GIS core capabilities allows immediate use of model results in a variety of existing online applications and integration with other data sources and applications.The poster presents the use of this framework to downscale global hydrologic models to local hydraulic scale and post process the hydraulic modeling results and generate floodplains at any local resolution. Flow forecasts from ECMWF or WRF-Hydro are downscaled and combined with other ancillary data for input into the RAPID flood routing model. RAPID model results (stream flow along each reach) are ingested into a GIS-based scale dependent stream network database for efficient flow utilization and visualization over space and time. Once the flows are known at localized reaches, the tools can be used to derive the floodplain depth and extent for each time step in the forecast at any available local resolution. If existing rating curves are available they can be used to relate the flow to the depth of flooding, or synthetic rating curves can be derived using the tools in the toolkit and some ancillary data/assumptions. The results can be published as time-enabled spatial services to be consumed by web applications that use floodplain information as an input. Some of the existing online presentation templates can be easily combined with available online demographic and infrastructure data to present the impact of the potential floods on the local community through simple, end user products. This framework
Physical Hydraulic Model of Side-Channel Spillway of Lambuk DAM, Bali
Harifa, A. C.; Sholichin, M.; Othman, F. B.
2013-12-01
The spillway is among the most important structures of a dam project. A spillway is designed to prevent overtopping of a dam at a place that is not designed for overtopping. Side-channel spillways are commonly used to release water flow from a reservoir in places where the sides are steep and have a considerable height above the dam. Experimental results were collected with a hydraulic model of the side-channel spillway for releasing the peak overflow of Lambuk Dam. This dam is, located on the Lambuk River, which is a tributary of the Yeh Hoo River ~ 34.6 km north of Denpasar on the island of Bali. The bituminous geomembrane faced dam is 24 m in height, with a 35-m wide spillway. The length of the side channel is 35 m long, with 58 m of transition channel, 67.37 m of chuteway channel and 22.71 m of stilling basin. The capacity of the spillway is 231.91 m3/s and the outlet works capacity is 165.28 m3/s. The reservoir is designed for irrigation and water supply. The purpose of this study was to optimize the designed of the structure and to ensure its safe operation. In hydraulic model may help the decision-makers to visualize the flow field before selecting a ';suitable' design. The hydraulic model study was performed to ensure passage of the maximum discharge at maximum reservoir capacity; to study the spillway approach conditions, water surface profiles, and flow patterns in the chuteway; and to reveal potential demerits of the proposed hydraulic design of various structures and explore solutions. The model was constructed at 1 : 40 scale, Reservoir topography was modeled using concrete, the river bed using sand and some gravel, the river berm using concrete, and the spillway and channel using Plexiglas. Water was measured using Rectangular contracted weir. Design floods (with return period in year) were Q2 = 111.40 m3/s, Q5 = 136.84 m3/s, Q10 = 159.32 m3/s, Q25 = 174.61 m3/s, Q50 = 185.13 m3/s, Q100 = 198.08 m3/s, Q200 = 210.55 m3/s, Q1000 = 231.91 m3/s and the
A high resolution coupled hydrologic-hydraulic model (HiResFlood-UCI) for flash flood modeling
Nguyen, Phu; Thorstensen, Andrea; Sorooshian, Soroosh; Hsu, Kuolin; AghaKouchak, Amir; Sanders, Brett; Koren, Victor; Cui, Zhengtao; Smith, Michael
2016-10-01
HiResFlood-UCI was developed by coupling the NWS's hydrologic model (HL-RDHM) with the hydraulic model (BreZo) for flash flood modeling at decameter resolutions. The coupled model uses HL-RDHM as a rainfall-runoff generator and replaces the routing scheme of HL-RDHM with the 2D hydraulic model (BreZo) in order to predict localized flood depths and velocities. A semi-automated technique of unstructured mesh generation was developed to cluster an adequate density of computational cells along river channels such that numerical errors are negligible compared with other sources of error, while ensuring that computational costs of the hydraulic model are kept to a bare minimum. HiResFlood-UCI was implemented for a watershed (ELDO2) in the DMIP2 experiment domain in Oklahoma. Using synthetic precipitation input, the model was tested for various components including HL-RDHM parameters (a priori versus calibrated), channel and floodplain Manning n values, DEM resolution (10 m versus 30 m) and computation mesh resolution (10 m+ versus 30 m+). Simulations with calibrated versus a priori parameters of HL-RDHM show that HiResFlood-UCI produces reasonable results with the a priori parameters from NWS. Sensitivities to hydraulic model resistance parameters, mesh resolution and DEM resolution are also identified, pointing to the importance of model calibration and validation for accurate prediction of localized flood intensities. HiResFlood-UCI performance was examined using 6 measured precipitation events as model input for model calibration and validation of the streamflow at the outlet. The Nash-Sutcliffe Efficiency (NSE) obtained ranges from 0.588 to 0.905. The model was also validated for the flooded map using USGS observed water level at an interior point. The predicted flood stage error is 0.82 m or less, based on a comparison to measured stage. Validation of stage and discharge predictions builds confidence in model predictions of flood extent and localized velocities
Chakrabarti, Suryarghya; Dapino, Marcelo J.
2010-04-01
A model is developed which describes the dynamic response of a Terfenol-D actuator with a hydraulic displacement amplification mechanism for use in active engine mounts. The model includes three main components: magnetic diffusion, Terfenol-D constitutive model, and mechanical actuator model. Eddy current losses are modeled as a one-dimensional magnetic field diffusion problem in cylindrical coordinates. The Jiles-Atherton model is used to describe the magnetization state of the Terfenol-D driver as a function of applied magnetic fields. A quadratic, single-valued model for the magnetostriction dependence on magnetization is utilized which provides an input to the mechanical model describing the system vibrations. Friction at the elastomeric seals is modeled using the LuGre friction model for lubricated contacts. The actuator's dynamic response is quantified in terms of the output displacement in the unloaded condition and force output in the loaded condition. The model is shown to accurately quantify the dynamic behavior of the actuator over the frequency range considered, from near dc to 500 Hz. An order analysis shows that the model also describes the higher harmonic content present in the measured responses. A study on the variation of energy delivered by the actuator with the load stiffness reveals that the actuator delivers the highest energy output near the stiffness match region.
Modeling Hydraulic Responses to Meteorological Forcing: fromCanopy to Aquifer
Energy Technology Data Exchange (ETDEWEB)
Pan, Lehua; Jin, Jiming; Miller, Norman; Wu, Yu-Shu; Bodvarsson,Gudmundur
2007-02-08
An understanding of the hydrologic interactions amongatmosphere, land surface, and subsurface is one of the keys tounderstanding the water cycling system that supports our life system onearth. Properly modeling such interactionsis a difficult task because oftheinherent coupled processes and complex feedback structures amongsubsystems. In this paper, we present a model that simulates thelandsurface and subsurface hydrologic response to meteorological forcing.This model combines a state of the art landsurface model, the NCARCommunity Land Model version 3 (CLM3), with a variablysaturatedgroundwater model, the TOUGH2, through an internal interfacethat includes flux and state variables shared by the two submodels.Specifically, TOUGH2, in its simulation, uses infiltration, evaporation,and rootuptake rates, calculated by CLM3, as source/sink terms? CLM3, inits simulation, uses saturation and capillary pressure profiles,calculated by TOUGH2, as state variables. This new model, CLMT2,preserves the best aspects of both submodels: the state of the artmodeling capability of surface energy and hydrologic processes from CLM3and the more realistic physical process based modeling capability ofsubsurface hydrologic processes from TOUGH2. The preliminary simulationresults show that the coupled model greatly improves the predictions ofthe water table, evapotranspiration, surface temperature, and moisture inthe top 20 cm of soil at a real watershed, as evaluated from 18 years ofobserved data. The new model is also ready to be coupled with anatmospheric simulation model, representing one of the first models thatare capable to simulate hydraulic processes from top of the atmosphere todeep ground.
Caldeira, Cecilio F; Bosio, Mickael; Parent, Boris; Jeanguenin, Linda; Chaumont, François; Tardieu, François
2014-04-01
Plants are constantly facing rapid changes in evaporative demand and soil water content, which affect their water status and growth. In apparent contradiction to a hydraulic hypothesis, leaf elongation rate (LER) declined in the morning and recovered upon soil rehydration considerably quicker than transpiration rate and leaf water potential (typical half-times of 30 min versus 1-2 h). The morning decline of LER began at very low light and transpiration and closely followed the stomatal opening of leaves receiving direct light, which represent a small fraction of leaf area. A simulation model in maize (Zea mays) suggests that these findings are still compatible with a hydraulic hypothesis. The small water flux linked to stomatal aperture would be sufficient to decrease water potentials of the xylem and growing tissues, thereby causing a rapid decline of simulated LER, while the simulated water potential of mature tissues declines more slowly due to a high hydraulic capacitance. The model also captured growth patterns in the evening or upon soil rehydration. Changes in plant hydraulic conductance partly counteracted those of transpiration. Root hydraulic conductivity increased continuously in the morning, consistent with the transcript abundance of Zea maize Plasma Membrane Intrinsic Protein aquaporins. Transgenic lines underproducing abscisic acid, with lower hydraulic conductivity and higher stomatal conductance, had a LER declining more rapidly than wild-type plants. Whole-genome transcriptome and phosphoproteome analyses suggested that the hydraulic processes proposed here might be associated with other rapidly occurring mechanisms. Overall, the mechanisms and model presented here may be an essential component of drought tolerance in naturally fluctuating evaporative demand and soil moisture.
Zhang, Donghua; Madsen, Henrik; Ridler, Marc E.; Refsgaard, Jens C.; Jensen, Karsten H.
2015-12-01
The ensemble Kalman filter (EnKF) is a popular data assimilation (DA) technique that has been extensively used in environmental sciences for combining complementary information from model predictions and observations. One of the major challenges in EnKF applications is the description of model uncertainty. In most hydrological EnKF applications, an ad hoc model uncertainty is defined with the aim of avoiding a collapse of the filter. The present work provides a systematic assessment of model uncertainty in DA applications based on combinations of forcing, model parameters, and state uncertainties. This is tested in a case where groundwater hydraulic heads are assimilated into a distributed and integrated catchment-scale model of the Karup catchment in Denmark. A series of synthetic data assimilation experiments are carried out to analyse the impact of different model uncertainty assumptions on the feasibility and efficiency of the assimilation. The synthetic data used in the assimilation study makes it possible to diagnose model uncertainty assumptions statistically. Besides the model uncertainty, other factors such as observation error, observation locations, and ensemble size are also analysed with respect to performance and sensitivity. Results show that inappropriate definition of model uncertainty can greatly degrade the assimilation performance, and an appropriate combination of different model uncertainty sources is advised.
Illman, Walter A.; Berg, Steven J.; Zhao, Zhanfeng
2015-05-01
The robust performance of hydraulic tomography (HT) based on geostatistics has been demonstrated through numerous synthetic, laboratory, and field studies. While geostatistical inverse methods offer many advantages, one key disadvantage is its highly parameterized nature, which renders it computationally intensive for large-scale problems. Another issue is that geostatistics-based HT may produce overly smooth images of subsurface heterogeneity when there are few monitoring interval data. Therefore, some may question the utility of the geostatistical inversion approach in certain situations and seek alternative approaches. To investigate these issues, we simultaneously calibrated different groundwater models with varying subsurface conceptualizations and parameter resolutions using a laboratory sandbox aquifer. The compared models included: (1) isotropic and anisotropic effective parameter models; (2) a heterogeneous model that faithfully represents the geological features; and (3) a heterogeneous model based on geostatistical inverse modeling. The performance of these models was assessed by quantitatively examining the results from model calibration and validation. Calibration data consisted of steady state drawdown data from eight pumping tests and validation data consisted of data from 16 separate pumping tests not used in the calibration effort. Results revealed that the geostatistical inversion approach performed the best among the approaches compared, although the geological model that faithfully represented stratigraphy came a close second. In addition, when the number of pumping tests available for inverse modeling was small, the geological modeling approach yielded more robust validation results. This suggests that better knowledge of stratigraphy obtained via geophysics or other means may contribute to improved results for HT.
Hydraulic Modeling of A Curtain-Walled Dissipater by the Coupling of RANS and Boussinesq Equations
Institute of Scientific and Technical Information of China (English)
齐鹏; 王永学
2002-01-01
A hybrid numerical method for the hydraulic modeling of a curtain-walled dissipater of reflected waves from breakwa-ters is presented. In this method, a zonal approach that combines a nonlinear weakly dispersive wave (Boussinesq-typeequation) method and a Reynolds-Averaged Navier-Stokes (RANS) method is used. The Boussinesq-type equation issolved in the far field to describe wave transformation in shallow water. The RANS method is used in the near field to re-solve the turbulent boundary layer and vortex flows around the structure. Suitable matching conditions are enforced at theinterface between the viscous and the Boussinesq region. The Coupled RANS and Boussinesq method successfully resolvesthe vortex characteristics of flow in the vicinity of the structure, while unexpected phenomena like wave re-reflection areeffectively controlled by lengthening the Boussinesq region. Extensive results on hydraulic performance of a curtain-walleddissipater and the mechanism of dissipation of reflected waves are presented, providing a reference for minimization of thebreadth of the water chamber and for determination of the submerged depth of the curtain wall.
Neutronic and Thermal-hydraulic Modelling of High Performance Light Water Reactor
Energy Technology Data Exchange (ETDEWEB)
Seppaelae, Malla [VTT Technical Research Centre of Finland, P.O.Box 1000, FI02044 VTT (Finland)
2008-07-01
High Performance Light Water Reactor (HPLWR), which is studied in EU project 'HPLWR2', uses water at supercritical pressures as coolant and moderator to achieve higher core outlet temperature and thus higher efficiency compared to present reactors. At VTT Technical Research Centre of Finland, functionality of the thermal-hydraulics in the coupled reactor dynamics code TRAB3D/ SMABRE was extended to supercritical pressures for the analyses of HPLWR. Input models for neutronics and thermal-hydraulics were made for TRAB3D/ SMABRE according to the latest HPLWR design. A preliminary analysis was performed in which the capability of SMABRE in the transition from supercritical pressures to subcritical pressures was demonstrated. Parameterized two-group cross sections for TRAB3D neutronics were received from Hungarian Academy of Sciences KFKI Atomic Energy Research Institute together with a subroutine for handling them. PSG, a new Monte Carlo transport code developed at VTT, was also used to generate two-group constants for HPLWR and comparisons were made with the KFKI cross sections and MCNP calculations. (author)
Hydraulic fracturing fluid migration in the subsurface: A review and expanded modeling results
Birdsell, Daniel T.; Rajaram, Harihar; Dempsey, David; Viswanathan, Hari S.
2015-09-01
Understanding the transport of hydraulic fracturing (HF) fluid that is injected into the deep subsurface for shale gas extraction is important to ensure that shallow drinking water aquifers are not contaminated. Topographically driven flow, overpressured shale reservoirs, permeable pathways such as faults or leaky wellbores, the increased formation pressure due to HF fluid injection, and the density contrast of the HF fluid to the surrounding brine can encourage upward HF fluid migration. In contrast, the very low shale permeability and capillary imbibition of water into partially saturated shale may sequester much of the HF fluid, and well production will remove HF fluid from the subsurface. We review the literature on important aspects of HF fluid migration. Single-phase flow and transport simulations are performed to quantify how much HF fluid is removed via the wellbore with flowback and produced water, how much reaches overlying aquifers, and how much is permanently sequestered by capillary imbibition, which is treated as a sink term based on a semianalytical, one-dimensional solution for two-phase flow. These simulations include all of the important aspects of HF fluid migration identified in the literature review and are performed in five stages to faithfully represent the typical operation of a hydraulically fractured well. No fracturing fluid reaches the aquifer without a permeable pathway. In the presence of a permeable pathway, 10 times more fracturing fluid reaches the aquifer if well production and capillary imbibition are not included in the model.
Thermal-Hydraulic Issues in the ITER Toroidal Field Model Coil (TFMC) Test and Analysis
Zanino, R.; Bagnasco, M.; Fillunger, H.; Heller, R.; Savoldi Richard, L.; Suesser, M.; Zahn, G.
2004-06-01
The International Thermonuclear Experimental Reactor (ITER) Toroidal Field Model Coil (TFMC) was tested in the Toska facility of Forschungszentrum Karlsruhe during 2001 (standalone) and 2002 (in the background magnetic field of the LCT coil). The TFMC is a racetrack coil wound in five double pancakes on stainless steel radial plates using Nb3Sn dual-channel cable-in-conduit conductor (CICC) with a thin circular SS jacket. The coil was cooled by supercritical helium in forced convection at nominal 4.5 K and 0.5 MPa. Instrumentation, all outside the coil, included voltage taps, pressure and temperature sensors, as well as flow meters. Additionally, differential pressure drop measurement was available on the two pancakes DP1.1 and DP1.2, equipped with heaters. Two major thermal-hydraulic issues in the TFMC tests will be addressed here: 1) the pressure drop along heated pancakes and the comparison with friction factor correlations; 2) the quench initiation and propagation. Other thermal-hydraulic issues like heat generation and exchange in joints, radial plates, coil case, or the effects of the resistive heaters on the helium dynamics, have been already addressed elsewhere.
Effect of Initial Hydraulic Conditions on Capillary Rise in a Porous Medium: Pore-Network Modeling
Joekar-Niasar, V.
2012-01-01
The dynamics of capillary rise in a porous medium have been mostly studied in initially dry systems. As initial saturation and initial hydraulic conditions in many natural and industrial porous media can be variable, it is important to investigate the influence of initial conditions on the dynamics of the process. In this study, using dynamic pore-network modeling, we simulated capillary rise in a porous medium for different initial saturations (and consequently initial capillary pressures). Furthermore, the effect of hydraulic connectivity of the wetting phase in corners on the height and velocity of the wetting front was studied. Our simulation results show that there is a trade-off between capillary forces and trapping due to snap-off, which leads to a nonlinear dependence of wetting front velocity on initial saturation at the pore scale. This analysis may provide a possible answer to the experimental observations in the literature showing a non-monotonic dependency between initial saturation and the macroscopic front velocity. © Soil Science Society of America.
Mohanty, B. P.; Bowman, R. S.; Hendrickx, J. M. H.; van Genuchten, M. T.
Modeling water flow in macroporous field soils near saturation has been a major challenge in vadose zone hydrology. Using in situ and laboratory measurements, we developed new piecewise-continuous soil water retention and hydraulic conductivity functions to describe preferential flow in tile drains under a flood-irrigated agricultural field in Las Nutrias, New Mexico. After incorporation into a two-dimensional numerical flow code, CHAIN_2D, the performance of the new piecewise-continuous hydraulic functions was compared with that of the unimodal van Genuchten-Mualem model and with measured tile-flow data at the field site during a number of irrigation events. Model parameters were collected/estimated by site characterization (e.g., soil texture, surface/subsurface saturated/unsaturated soil hydraulic property measurements), as well as by local and regional-scale hydrologic monitoring (including the use of groundwater monitoring wells, piezometers, and different surface-irrigation and subsurface-drainage measurement systems). Comparison of numerical simulation results with the observed tile flow indicated that the new piecewise-continuous hydraulic functions generally predicted preferential flow in the tile drain reasonably well following all irrigation events at the field site. Also, the new bimodal soil water retention and hydraulic conductivity functions performed better than the unimodal van Genuchten-Mualem functions in terms of describing the observed flow regime at the field site.
Numeric Simulation of Single Passage Ternary Turbulence Model in Hydraulic Torque Converter
Institute of Scientific and Technical Information of China (English)
闫清东; 魏巍
2003-01-01
Based on the renormalization group theory, a hydraulic torque converter 3-D turbulent single flow passage model is constructed and boundary condition is determined for analyzing the influence of the fluid field characteristic and parameters on the macroscopic model. Numerical simulation of the single fluid path is processed by computational fluid dynamics and the calculated results approach to experimental data well, and especially in low transmission ratio the torque and head results are more close to experimental data than the calculated results of beam theory. This shows that the appropriate ternary analysis method and reasonable assumption of boundary condition may analyze the flow field more precisely and predict the performance of torque converter more accurately.
Hydraulic model of a gas-lift bioreactor with flocculating yeast
Energy Technology Data Exchange (ETDEWEB)
Roca, E. [Chemical Engineering Dept., Univ. of Santiago de Compostela (Spain); Ghommidh, C. [G.B.S.A. Microbiologie et Biochimie Industrielle. Univ. Montpellier 2, 34 Montpellier (France); Navarro, J.M. [G.B.S.A. Microbiologie et Biochimie Industrielle. Univ. Montpellier 2, 34 Montpellier (France); Lema, J.M. [Chemical Engineering Dept., Univ. of Santiago de Compostela (Spain)
1995-04-01
The hydraulic model of a gas lift bioreactor, during a continuous alcoholic fermentation by using a strongly flocculating yeast, is analysed. Sucrose at two different concentrations (50 and 100 g/l) was used as substrate and the dilution rate for all the experiments was 1 h{sup -1}. The biomass concentrations were between 85 and 110 g dry weight/l. A stimulus response technique was used to obtain the Residence Time Distribution curves, a pulse of a lactose solution being used as the tracer. Mixing time was determined by means of the response to a pulse of an acid tracer. These experiments were carried out by using an on-line data-acquisition system. The bioreactor behaviour is completely homogeneous, except for high substrate and biomass concentrations. A two parameters combined model is necessary, in this case, to fit the experimental data. Mixing times are very low, in the order of 10 seconds. (orig.)
DEFF Research Database (Denmark)
Jensen, M.D.; Ingildsen, P.; Rasmussen, Michael R.;
2006-01-01
Aeration tank settling is a control method allowing settling in the process tank during highhydraulic load. The control method is patented. Aeration tank settling has been applied in several wastewater treatment plants using the present design of the process tanks. Some process tank designs...... haveshown to be more effective than others. To improve the design of less effective plants, computational fluiddynamics (CFD) modelling of hydraulics and sedimentation has been applied. This paper discusses theresults at one particular plant experiencing problems with partly short-circuiting of the inlet...... and outletcausing a disruption of the sludge blanket at the outlet and thereby reducing the retention of sludge in theprocess tank. The model has allowed us to establish a clear picture of the problems arising at the plantduring aeration tank settling. Secondly, several process tank design changes have been...
Experimental Validation of Modelled Fluid Forces in Fast Switching Hydraulic On/Off Valves
DEFF Research Database (Denmark)
Nørgård, Christian; Bech, Michael Møller; Roemer, Daniel Beck;
2015-01-01
A prototype of a fast switching valve for a digital hydraulic machine has been designed and manufactured. The valve is composed of an annular seat plunger connected with a moving coil actuator as the force producing element. The valve prototype is designed for flow rates of 600 l/min with less than...... 0.5 bar pressure drop, and the models predicts a switching time in the region of a millisecond with a travel length of 3.5 mm using an average power of 250 W. The total machine efficiency when neglecting losses not related to the valves is above 98 %. The objective of this paper is to experimentally...... validate a transient computational fluid dynamics (CFD) model of the fluid forces that oppose the valve plunger when moving rapidly through the surrounding oil during switching. Due to the fast switching of the valve, the fluid forces which oppose plunger movement increases drastically as the plunger...
Directory of Open Access Journals (Sweden)
Gaurav Savant
2014-01-01
Full Text Available The adaptive hydraulics (AdH numerical code was applied to study tidal propagation in the Lower Columbia River (LCR estuary. The results demonstrate the readiness of this AdH model towards the further study of hydrodynamics in the LCR. The AdH model accurately replicated behavior of the tide as it propagated upstream into the LCR system. Results show that the MSf tidal component and the M4 overtidal component are generated in the middle LCR and contain a substantial amount of tidal energy. An analysis was performed to determine the causes of MSf tide amplification, and it was found that approximately 80% of the amplification occurs due to nonlinear interaction between the M2 and the S2 tidal components.
Modeling coupled nitrogen and water use strategies of plant productivity through hydraulic traits
Mackay, D. S.; Savoy, P.; Pleban, J. R.; Tai, X.; Ewers, B. E.; Sperry, J.; Weinig, C.
2016-12-01
Changes in heat, nutrient, and drought stresses create novel environments that threaten the health of forests and viability of crop production. Here a trait-based conceptual model finds tradeoffs in maximum hydraulic conductance (Kmax), root to leaf area ratio (RLA) and vulnerability to cavitation (VC) based on the energy costs of acquiring water and nitrogen (N) to support gross primary production (GPP). The atmosphere supplies carbon to and demands water from plants via their stomata. The demand for water increases at higher temperatures due to increased vapor pressure deficits. The lost water is replenished by a passive wicking process that pulls water and N from the soil into roots and up water-filled xylem tubes. When water is in short supply the cost of getting it is high as measured by a decline in K and stomatal closure. Soil N dynamics also influence plant water use. When N is abundant, plants grow low VC fine roots with lower specific root length (m g-1), low Kmax, and maintain a relatively low RLA. In low N environments, N is costly and fine roots gain efficiency by building less robust (or higher VC) xylem with higher Kmax and higher RLA. What happens when the cost of acquiring water changes from high to low under low and high N costs? We incorporated the conceptual model into TREES, which couples whole plant hydraulics to carbon allocation, root-rhizosphere expansion/contraction and, also new for this study, a rhizosphere-root centric microbe-plant N dynamics. We used two experimental studies (drought, N) and two drought-prone fluxnet sites to test the conceptual model at individual plant and regional scales, respectively, and with frequent short versus infrequent long dry periods. When water was not limiting the hydraulic tradeoffs suppressed differences in GPP between the N use strategies. When water was in short supply, however, low RLA&VC plants dropped GPP early during drought because of low Kmax. Since these plants had low VC roots they also
Energy Technology Data Exchange (ETDEWEB)
Anh Bui; Nam Dinh; Brian Williams
2013-09-01
In addition to validation data plan, development of advanced techniques for calibration and validation of complex multiscale, multiphysics nuclear reactor simulation codes are a main objective of the CASL VUQ plan. Advanced modeling of LWR systems normally involves a range of physico-chemical models describing multiple interacting phenomena, such as thermal hydraulics, reactor physics, coolant chemistry, etc., which occur over a wide range of spatial and temporal scales. To a large extent, the accuracy of (and uncertainty in) overall model predictions is determined by the correctness of various sub-models, which are not conservation-laws based, but empirically derived from measurement data. Such sub-models normally require extensive calibration before the models can be applied to analysis of real reactor problems. This work demonstrates a case study of calibration of a common model of subcooled flow boiling, which is an important multiscale, multiphysics phenomenon in LWR thermal hydraulics. The calibration process is based on a new strategy of model-data integration, in which, all sub-models are simultaneously analyzed and calibrated using multiple sets of data of different types. Specifically, both data on large-scale distributions of void fraction and fluid temperature and data on small-scale physics of wall evaporation were simultaneously used in this work’s calibration. In a departure from traditional (or common-sense) practice of tuning/calibrating complex models, a modern calibration technique based on statistical modeling and Bayesian inference was employed, which allowed simultaneous calibration of multiple sub-models (and related parameters) using different datasets. Quality of data (relevancy, scalability, and uncertainty) could be taken into consideration in the calibration process. This work presents a step forward in the development and realization of the “CIPS Validation Data Plan” at the Consortium for Advanced Simulation of LWRs to enable
Jong, de Q.; Dam, van J.C.; Durigon, A.; Santos, dos M.A.; Metselaar, K.
2013-01-01
Crop transpiration depends on resistances in the soil–plant–atmosphere system. We present a new deterministic root water uptake model to estimate transpiration and compare it with two other models. We show the sensitivity of actual transpiration to parameters like soil and plant hydraulic properties
A seventh-order model for dynamic response of an electro-hydraulic servo valve
Institute of Scientific and Technical Information of China (English)
Liu Changhai; Jiang Hongzhou
2014-01-01
In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from nonlinear equations. These deductions are based on fundamental laws of electromagnetism, fluid, and general mechanics. The coefficients of the proposed seventh-order model are derived in terms of servo valve physical parameters and fluid properties explicitly. For validating the results of the proposed model, an AMESim simulation model based on physical laws and the existing low-order models validated by other researchers through experiments are used to compare with the seventh-order model. The results show that the seventh-order model can reflect the physical behavior of the servo valve more explicitly than the existing low-order models and it could provide guidance more easily for a linear control design approach and sensitivity analysis than the AMESim simulation model.
Wilson, J. P.; Fischer, W. W.
2010-12-01
Fossil plants provide useful proxies of Earth’s climate because plants are closely connected, through physiology and morphology, to the environments in which they lived. Recent advances in quantitative hydraulic models of plant water transport provide new insight into the history of climate by allowing fossils to speak directly to environmental conditions based on preserved internal anatomy. We report results of a quantitative hydraulic model applied to one of the earliest terrestrial plants preserved in three dimensions, the ~396 million-year-old vascular plant Asteroxylon mackei. This model combines equations describing the rate of fluid flow through plant tissues with detailed observations of plant anatomy; this allows quantitative estimates of two critical aspects of plant function. First and foremost, results from these models quantify the supply of water to evaporative surfaces; second, results describe the ability of plant vascular systems to resist tensile damage from extreme environmental events, such as drought or frost. This approach permits quantitative comparisons of functional aspects of Asteroxylon with other extinct and extant plants, informs the quality of plant-based environmental proxies, and provides concrete data that can be input into climate models. Results indicate that despite their small size, water transport cells in Asteroxylon could supply a large volume of water to the plant's leaves--even greater than cells from some later-evolved seed plants. The smallest Asteroxylon tracheids have conductivities exceeding 0.015 m^2 / MPa * s, whereas Paleozoic conifer tracheids do not reach this threshold until they are three times wider. However, this increase in conductivity came at the cost of little to no adaptations for transport safety, placing the plant’s vegetative organs in jeopardy during drought events. Analysis of the thickness-to-span ratio of Asteroxylon’s tracheids suggests that environmental conditions of reduced relative
Simulating High Flux Isotope Reactor Core Thermal-Hydraulics via Interdimensional Model Coupling
Energy Technology Data Exchange (ETDEWEB)
Travis, Adam R [ORNL
2014-05-01
A coupled interdimensional model is presented for the simulation of the thermal-hydraulic characteristics of the High Flux Isotope Reactor core at Oak Ridge National Laboratory. The model consists of two domains a solid involute fuel plate and the surrounding liquid coolant channel. The fuel plate is modeled explicitly in three-dimensions. The coolant channel is approximated as a twodimensional slice oriented perpendicular to the fuel plate s surface. The two dimensionally-inconsistent domains are linked to one another via interdimensional model coupling mechanisms. The coupled model is presented as a simplified alternative to a fully explicit, fully three-dimensional model. Involute geometries were constructed in SolidWorks. Derivations of the involute construction equations are presented. Geometries were then imported into COMSOL Multiphysics for simulation and modeling. Both models are described in detail so as to highlight their respective attributes in the 3D model, the pursuit of an accurate, reliable, and complete solution; in the coupled model, the intent to simplify the modeling domain as much as possible without affecting significant alterations to the solution. The coupled model was created with the goal of permitting larger portions of the reactor core to be modeled at once without a significant sacrifice to solution integrity. As such, particular care is given to validating incorporated model simplifications. To the greatest extent possible, the decrease in solution time as well as computational cost are quantified versus the effects such gains have on the solution quality. A variant of the coupled model which sufficiently balances these three solution characteristics is presented alongside the more comprehensive 3D model for comparison and validation.
Shen, D.; Wang, J.; Cheng, X.; Rui, Y.; Ye, S.
2015-08-01
The rapid progress of lidar technology has made the acquirement and application of high-resolution digital elevation model (DEM) data increasingly popular, especially in regards to the study of floodplain flow. However, high-resolution DEM data pose several disadvantages for floodplain modeling studies; e.g., the data sets contain many redundant interpolation points, large numbers of calculations are required to work with data, and the data do not match the size of the computational mesh. Two-dimensional (2-D) hydraulic modeling, which is a popular method for analyzing floodplain flow, offers highly precise elevation parameterization for computational mesh while ignoring much of the micro-topographic information of the DEM data itself. We offer a flood simulation method that integrates 2-D hydraulic model results and high-resolution DEM data, thus enabling the calculation of flood water levels in DEM grid cells through local inverse distance-weighted interpolation. To get rid of the false inundation areas during interpolation, it employs the run-length encoding method to mark the inundated DEM grid cells and determine the real inundation areas through the run-length boundary tracing technique, which solves the complicated problem of connectivity between DEM grid cells. We constructed a 2-D hydraulic model for the Gongshuangcha detention basin, which is a flood storage area of Dongting Lake in China, by using our integrated method to simulate the floodplain flow. The results demonstrate that this method can solve DEM associated problems efficiently and simulate flooding processes with greater accuracy than simulations only with DEM.
Electron-plasmon model in the electron liquid theory
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M.V.Vavrukh
2005-01-01
Full Text Available Here we propose an accurate approach to the description of the electron liquid model in the electron and plasmon terms. Our ideas in the present paper are close to the conception of the collective variables which was developed in the papers of Bohm and Pines. However we use another body of mathematics in the transition to the expanded space of variable particles and plasmons realized by the transition operator. It is evident that in the Random Phase Approximation (RPA, the model which consists of two interactive subsystems of electrons and plasmons is equivalent to the electron liquid model with Coulomb interaction.
Hydraulic Press with LS System for Modelling of Plastic Working Operations
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Janusz Pluta
2008-03-01
Full Text Available At first, the paper describes destination of the presented hydraulic press. Next, the substance of load sensing (LS systems’ operation was introduced, and electro-hydraulic system of this type, installed in laboratory hydraulic press, was described. The control and measurement circuit of the device was also described, and exemplary test results obtained during plastic working operations on soft non-ferrous alloys were presented.
Transient thermal hydraulic modeling and analysis of ITER divertor plate system
Energy Technology Data Exchange (ETDEWEB)
El-Morshedy, Salah El-Din [Argonne National Laboratory, Argonne, IL (United States); Atomic Energy Authority, Cairo (Egypt)], E-mail: selmorshedy@etrr2-aea.org.eg; Hassanein, Ahmed [Purdue University, West Lafayette, IN (United States)], E-mail: hassanein@purdue.edu
2009-12-15
A mathematical model has been developed/updated to simulate the steady state and transient thermal-hydraulics of the International Thermonuclear Experimental Reactor (ITER) divertor module. The model predicts the thermal response of the armour coating, divertor plate structural materials and coolant channels. The selected heat transfer correlations cover all operating conditions of ITER under both normal and off-normal situations. The model also accounts for the melting, vaporization, and solidification of the armour material. The developed model is to provide a quick benchmark of the HEIGHTS multidimensional comprehensive simulation package. The present model divides the coolant channels into a specified axial regions and the divertor plate into a specified radial zones, then a two-dimensional heat conduction calculation is created to predict the temperature distribution for both steady and transient states. The model is benchmarked against experimental data performed at Sandia National Laboratory for both bare and swirl tape coolant channel mockups. The results show very good agreements with the data for steady and transient states. The model is then used to predict the thermal behavior of the ITER plasma facing and structural materials due to plasma instability event where 60 MJ/m{sup 2} plasma energy is deposited over 500 ms. The results for ITER divertor response is analyzed and compared with HEIGHTS results.
Directory of Open Access Journals (Sweden)
Juan Carlos Antolín-Urbaneja
2015-03-01
Full Text Available One of the key systems of a Wave Energy Converter for extraction of wave energy is the Power Take-Off (PTO device. This device transforms the mechanical energy of a moving body into electrical energy. This paper describes the model of an innovative PTO based on independently activated double-acting hydraulic cylinders array. The model has been developed using a simulation tool, based on a port-based approach to model hydraulics systems. The components and subsystems used in the model have been parameterized as real components and their values experimentally obtained from an existing prototype. In fact, the model takes into account most of the hydraulic losses of each component. The simulations show the flexibility to apply different restraining torques to the input movement depending on the geometrical configuration and the hydraulic cylinders on duty, easily modified by a control law. The combination of these two actions allows suitable flexibility to adapt the device to different sea states whilst optimizing the energy extraction. The model has been validated using a real test bench showing good correlations between simulation and experimental tests.
Coupling of Thermal-Hydraulic-Mechanical Processes for Geothermal Reservoir Modelling
Institute of Scientific and Technical Information of China (English)
Ali Karrechl Oussama Beltaief; Ruyan Vincec; Thomas Poulet; Klaus Regenauer-Lieb
2015-01-01
This paper uses a fully coupled framework of thermal-hydraulic-mechanical processes to investigate how the injection and extraction of fluid within a geothermal reservoir impacts on the dis-tributions of temperature, pore pressure, and deformation within the rock formations. Based on this formulation, a numerical model is developed in light of the thermodynamics of porous materials. The proposed procedure relies on the derivation of dissipative flow rules by postulating proper storage and dissipation functions. This approach opens new horizons for several resource engineering applications. Since it allows for full coupling, this formulation can play a key role in predicting risks when used for reservoir simulation. The results indicate that the injection-extraction process and temperature change have a definite impact on altering the in-situ properties of the reservoir.
Energy Technology Data Exchange (ETDEWEB)
Marengo Mogollon, Humberto [Comision Federal de Electricidad (Mexico)
2001-03-01
Sediment remotion in reservoirs has received an increased attention worldwide because of the difficulty to build new dams. This paper shows the application of some flushing techniques in two hydraulic experimental models that were used in order to estimate the efficiency in sediment remotion, as well as feasible solutions to be applied in our country. [Spanish] La remocion de sedimentos que se acumulan en los embalses ha recibido recientemente una gran atencion en diversas partes del mundo debido fundamentalmente a la dificultad de construir nuevas presas. Este articulo muestra el uso de la remocion hidraulica de sedimentos en embalses aplicados a dos modelos hidraulicos experimentales que se emplearon para estimar la eficiencia de dicha remocion, ademas de posibles soluciones que se consideran factibles de utilizarse en nuestro pais.
Development of a numerical hydraulic model of the Los Azufres steam pipeline network
Energy Technology Data Exchange (ETDEWEB)
Garcia-Gutierrez, Alfonso; Martinez-Estrella, Juan Ignacio; Hernandez-Ochoa, Abel Felipe; Verma, Mahendra P. [Instituto de Investigaciones Electricas, Ave. Reforma 113, Col. Palmira, 62490 Cuernavaca, Mor. (Mexico); Mendoza-Covarrubias, Alfredo; Ruiz-Lemus, Alejandro [Comision Federal de Electricidad, Campo Geotermico Los Azufres, Campamento Agua Fria, Mich. (Mexico)
2009-09-15
The development and documentation of a hydraulic model of the steam pipeline network at the Los Azufres geothermal field is presented, as well as the results obtained using one- and two-phase numerical simulators. Flow simulations were performed to determine pressure and heat losses, flow directions and velocities in that network. Computed well pressures agree within {+-}10% with measured values, except in three of the 41 wells in the system where the differences are between 10% and 13%. Computed and measured steam flow rates entering the Los Azufres geothermal power plants agree within 10%, with the exception of one that showed a 26.7% difference. This is most likely due to a mismatch between the reported and actual flow rates delivered by the pipeline network. The computed results are considered highly satisfactory given the complexity of the Los Azufres network. (author)
Directory of Open Access Journals (Sweden)
Tri-Vien Vu
2014-10-01
Full Text Available This study applied a model predictive control (MPC framework to solve the cruising control problem of a series hydraulic hybrid vehicle (SHHV. The controller not only regulates vehicle velocity, but also engine torque, engine speed, and accumulator pressure to their corresponding reference values. At each time step, a quadratic programming problem is solved within a predictive horizon to obtain the optimal control inputs. The objective is to minimize the output error. This approach ensures that the components operate at high efficiency thereby improving the total efficiency of the system. The proposed SHHV control system was evaluated under urban and highway driving conditions. By handling constraints and input-output interactions, the MPC-based control system ensures that the system operates safely and efficiently. The fuel economy of the proposed control scheme shows a noticeable improvement in comparison with the PID-based system, in which three Proportional-Integral-Derivative (PID controllers are used for cruising control.
Modeling Flow Rate to Estimate Hydraulic Conductivity in a Parabolic Ceramic Water Filter
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Ileana Wald
2012-01-01
Full Text Available In this project we model volumetric flow rate through a parabolic ceramic water filter (CWF to determine how quickly it can process water while still improving its quality. The volumetric flow rate is dependent upon the pore size of the filter, the surface area, and the height of water in the filter (hydraulic head. We derive differential equations governing this flow from the conservation of mass principle and Darcy's Law and find the flow rate with respect to time. We then use methods of calculus to find optimal specifications for the filter. This work is related to the research conducted in Dr. James R. Mihelcic's Civil and Environmental Engineering Lab at USF.
Directory of Open Access Journals (Sweden)
MOKHTAR CHE ISMAIL
2011-12-01
Full Text Available Pipelines transporting oil and gas are vulnerable to internal corrosion when water forms a part of the transported fluids. The presence of carbon dioxide (CO2 in the fluid accelerates the corrosion rate due to its reaction with water which results in forming carbonic acid, and hence, water pH is reduced. The corrosion rate prediction is an important task needed to manage and control the corrosion. The prediction can be carried on by selecting one of many empirical and mechanistic models that developed for corrosion rate prediction. One of these models is NORSOK model, an empirical model developed by NORSOK Norwegian standard for CO2 corrosion prediction in straight pipes. In this paper NORSOK model has been coupled to thermal and hydraulic models to predict CO2 corrosion rate along pipelines.
Grimaldi, Stefania; Li, Yuan; Pauwels, Valentijn R. N.; Walker, Jeffrey P.
2016-09-01
Accurate, precise and timely forecasts of flood wave arrival time, depth and velocity at each point of the floodplain are essential to reduce damage and save lives. Current computational capabilities support hydraulic models of increasing complexity over extended catchments. Yet a number of sources of uncertainty (e.g., input and boundary conditions, implementation data) may hinder the delivery of accurate predictions. Field gauging data of water levels and discharge have traditionally been used for hydraulic model calibration, validation and real-time constraint. However, the discrete spatial distribution of field data impedes the testing of the model skill at the two-dimensional scale. The increasing availability of spatially distributed remote sensing (RS) observations of flood extent and water level offers the opportunity for a comprehensive analysis of the predictive capability of hydraulic models. The adequate use of the large amount of information offered by RS observations triggers a series of challenging questions on the resolution, accuracy and frequency of acquisition of RS observations; on RS data processing algorithms; and on calibration, validation and data assimilation protocols. This paper presents a review of the availability of RS observations of flood extent and levels, and their use for calibration, validation and real-time constraint of hydraulic flood forecasting models. A number of conclusions and recommendations for future research are drawn with the aim of harmonising the pace of technological developments and their applications.
Trauth, N.; Schmidt, C.; Fleckenstein, J. H.
2013-12-01
Exchange of water and solutes across the stream-sediment interface is an important control for biogeochemical transformations in the hyporheic zone (HZ) with measurable impacts on nutrient cycling and solute attenuation in fluvial systems. Here we investigate the interplay between turbulent stream flow and HZ flow under various hydraulic conditions applied to two cases: a) three-dimensional generic pool-riffle sequences with different morphological properties, and b) a real mid-stream gravel-bar. Stream flow is simulated by the open source computational fluid dynamics (CFD) software OpenFOAM which provides the hydraulic head distribution at the streambed. It is sequentially coupled to the top of the groundwater model code MIN3P, simulating flow, solute transport, aerobic respiration (AR) and denitrification (DN) in the HZ. Flow in the HZ is directly influenced by the hydraulic head distribution at the streambed surface and the ambient groundwater flow. Three reactive transport scenarios are considered: 1) stream water as the primary source of dissolved oxygen (DO), nitrate (NO3) and dissolved organic carbon (DOC), 2) upwelling groundwater as an additionally source of NO3, and 3) upwelling groundwater as an additional source of DO in various concentrations. Results show an increase in hyporheic exchange flow for increasing stream discharge with a concurrent decrease in residence time. The fraction of circulating stream water through the HZ is in the range of 1x10-5 to 1x10-6 per unit stream length, decreasing with increasing discharge. Ambient groundwater flow in both the up- and downwelling direction diminishes significantly the hyporheic exchange flow and extent. Biogeochemical processes in the HZ are strongly controlled by ambient groundwater flow, even more so than by changes in stream discharge. AR and DN efficiencies of the HZ are significantly reduced by up- and downwelling groundwater and are positively correlated with median residence times. AR occurs in
Energy Technology Data Exchange (ETDEWEB)
Megel, T. [Inst. fuer Geophysik, Gruppe fuer Geothermik und Radiometrie, ETH Hoenggerberg, Zuerich (Switzerland); Wyss, R. [Ingenieurgelogie, ETH Hoenggerberg, Zuerich (Switzerland); Greber, E.; Leu, W. [Geoform, Geologische Beratungen und Studien AG, Winterthur (Switzerland)
1997-12-01
Aussuming an aquifer of minimum 30 km extension, modelling and interpretation of the hydraulic situation at the geothermal wells Konstanz and Kreuzlingen have shown, that there is neither a significant hydraulic nor a thermal interrelation between the two wells (assumed production rate: Konstanz 6.6 l/s, Kreuzlingen 3 l/s). Every hydraulic behaviour of supposed fracture zones between the two wells reduces the interrelated influence. (orig.) [Deutsch] Modellierungen und Interpretationen haben gezeigt, dass unter der Annahme eines mindestens 30 km ausgedehnten Aquifers die Geothermiebohrungen Konstanz und Kreuzlingen auch laengerfristig (30 Jahre) sich gegenseitig weder hydraulisch noch thermisch nennenswert beeinflussen (Konstanz 6.6 l/s, Kreuzlingen 3 l/s). Die Existenz von hydraulisch signifikanten Bruchzonen zwischen den beiden Bohrungen wuerde die gegenseitige Beeinflussung vermindern. (orig.)
Fabris, L.; Malcolm, I.; Millidine, K. J.; Buddendorf, B.; Tetzlaff, D.; Soulsby, C.
2015-12-01
Wild Atlantic salmon populations in Scottish rivers constitute an important economic and recreational resource, as well as being a key component of biodiversity. Salmon have very specific habitat requirements at different life stages and their distribution is therefore strongly influenced by a complex suite of biological and physical controls. Previous research has shown that stream hydrodynamics and channel morphology have a strong influence on the distribution and density of juvenile salmon. Here, we utilise a unique 20 year data set of spatially distributed juvenile salmon densities derived from annual electro-fishing surveys in an upland Scottish river. We examine to what extent the spatial and temporal variability of in-stream hydraulics regulates the spatial and temporal variability in the performance and density of juvenile salmon. A 2-D hydraulic model (River2D) is used to simulate water velocity and water depth under different flow conditions for seven different electro-fishing sites. The selected sites represent different hydromorphological environments including plane-bed, step-pool and pool riffle reaches. The bathymetry of each site was characterised using a total station providing an accurate DTM of the bed, and hydraulic simulations were driven by 20 year stream flow records. Habitat suitability curves, based on direct observations during electro-fishing surveys, were produced for a range of hydraulic indices for juvenile salmon. The hydraulic simulations showed marked spatial differences in juvenile habitat quality both within and between reaches. They also showed marked differences both within and between years. This is most evident in extreme years with wet summers when salmon feeding opportunities may be constrained. Integration of hydraulic habitat models, with fish preference curves and the long term hydrological data allows us to assess whether long-term changes in hydroclimate may be affecting juvenile salmonid populations in the study stream
Battiston, Stéphanie; Allenbach, Bernard
2010-05-01
compartments; high resolution optical imagery allow the exhaustive inventory of breaches and overflows; turbidity variations and draw-off give information on stream directions. These facts are of primary interest to help in deriving a firm understanding of the flooding processes, but also comprise a powerful source for the necessary parameterization and/or calibration of hydraulic models. Thus the accuracy of flood extents derived from remote sensing data could, on the one hand, be valuable inputs to historical flood info-bases within overall risk-linked databases, and on the other hand, test the validity of hydrological modelling, while helping to lift equifinality uncertainties. These first investigations highlight that space imagery of events constitutes an unrivalled tool for flood disaster observation. This 2D record is complementary to all field measurements and the integration of "space derived flood products" is valuable for all stages of risk management. This potential of EO optical sensors for flood monitoring is also confirmed in a detailed analysis making a qualitative and quantitative evaluation of the results, confronting ten optical and radar remote sensing platforms with field observations.
Sea Water Quality Modeling in the Frame of a Building First Turn of a Hydraulic Engineering Complex
Directory of Open Access Journals (Sweden)
Igor G. Kantargi
2012-05-01
Full Text Available The article deals with an application of developed system-dynamic model of the coastal waters quality for an assessment of sea water quality in the frame of building 1 turn of a hydraulic engineering complex "Object" the Island Federation». The attention is paid to a coast site with a coastal protection constructions.
DEFF Research Database (Denmark)
Conrad, Finn
2006-01-01
The paper presents and discusses a R&D-view on trends in development and best practise in modelling, simulation and design of both low-pressure and high-pressure tap water hydraulic components and systems for motion control as well as open-ended solutions various industrial applications. The focus...
Directory of Open Access Journals (Sweden)
Zaini Dalimus
2016-07-01
Full Text Available In mixed-mode braking applications, the electric motor / generator (M/G and hydraulic pressure valve are controlled to meet the driver’s braking demand. Controlling these braking elements is achieved by modulating the current generated by the M/G and adjusting the fluid pressure to the wheel brake cylinders. This paper aims to model and design combined regenerative and hydraulic braking systems which, comprise an induction electric machine, inverter, NiMH battery, controller, a pressure source, pressure control unit, and brake calipers. A 15 kW 1500 rpm induction machine equipped with a reduction gear having a gear ratio of 4 is used. A hydraulic brake capable to produce fluid pressure up to 40 bar is used. Direct torque control and pressure control are chosen as the control criteria in the M/G and the hydraulic solenoid valve. The braking demands for the system are derived from the Federal Testing Procedure (FTP drive cycle. Two simulation models have been developed in Matlab®/Simulink® to analyze the performance of the control strategy in each braking system. The developed model is validated through experiment. It is concluded that the control system does introduce torque ripple and pressure oscillation in the braking system, but these effects do not affect vehicle braking performance due to the high frequency nature of pressure fluctuation and the damping effect of the vehicle inertia. Moreover, experiment results prove the effectiveness of the developed model.
Hydraulic lift in a neotropical savanna: experimental manipulation and model simulations
Fabian G. Scholz; Sandra J. Bucci; William A. Hoffmann; Frederick C. Meinzer; Guillermo Goldstein
2010-01-01
The objective of this study was to assess the magnitude of hydraulic lift in Brazilian savannas (Cerrado) and to test the hypothesis that hydraulic lift by herbaceous plants contributes substantially to slowing the decline of water potential and water storage in the upper soil layers during the dry season. To this effect, field observations of soil water content and...
Xanthopoulou, Themis; Ertsen, Maurits; Düring, Bleda; Kolen, Jan
2017-04-01
In the dry Southern Oman, more than a thousand years ago, a large water system that connected the mountain mass with the coastal region was constructed. Its length (up to 30 km) and the fact that the coastal region has a rich groundwater aquifer create confusion as to why the system was initially built. Nonetheless, it was abandoned a couple of centuries later only to be partially revived by small farming communities in the 17th to 18th century. The focus of our research is one of the irrigation systems that used the water conveyed from the large water system. Not much is known about these small irrigation systems functioning in the Wadi Al Jizzi of the greater Sohar region. There are no written records and we can only make guesses about the way the systems were managed based on ethnographical studies and the traditional Omani techniques. On the other hand, the good preservation state of the canals offers a great opportunity for hydraulic reconstruction of irrigation events. More than that, the material remains suggest and at the same time limit the ways in which humans interacted with the system and the water resources of the region. All irrigation activities and some daily activities had to be realized through the canal system and only if the canal system permits it these actions would have been feasible. We created a conceptual model of irrigation that includes the human agent and feedback mechanisms through hydraulics and then we simulated irrigation events using the Sobek software. Scenarios and sensibility analysis were used to address the unknown aspects of the system. Our research yielded insights about the way the farming community interacted with the larger water system, the levels of co-ordination and co-operation required for successful irrigation and the predisposition of conflict and power relations.
Modeling of excavation induced coupled hydraulic-mechanical processes in claystone
Energy Technology Data Exchange (ETDEWEB)
Massmann, Jobst
2009-07-01
Concepts for the numerical modeling of excavation induced processes in claystone are investigated. The study has been motivated by the international discussion on the adequacy of claystone as a potential host rock for a final repository of radioactive waste. The processes, which could impact the safety of such a repository, are manifold and strongly interacting. Thus, a multiphysics approach is needed, regarding solid mechanics and fluid mechanics within a geological context. A coupled modeling concept is therefore indispensable. Based on observations and measurements at an argillaceous test site (the underground laboratory Tournemire, operated by the Institute of Radioprotection and Nuclear Safety, France) the modeling concept is developed. Two main processes constitute the basis of the applied model: deformation (linear elasticity considering damage) and fluid flow (unsaturated one-phase flow). Several coupling phenomena are considered: Terzaghi 's effective stress concept, mass conservation of the liquid in a deformable porous media, drying induced shrinkage, and a permeability which depends on deformation and damage. In addition, transversely isotropic material behavior is considered. The numerical simulations are done with the finite element code RockFlow, which is extended to include: an orthotropic non-linear shrinkage model, a continuum damage model, and an orthotropic permeability model. For these new methods the theory and a literature review are presented, followed by applications, which illustrate the capability to model excavation induced processes in principle. In a comprehensive case study, the modeling concept is used to simulate the response of the Tournemire argillite to excavation. The results are compared with observations and measurements of three different excavations (century old tunnel, two galleries excavated in 1996 and 2003). In summary, it can be concluded that the developed model concept provides a prediction of the excavation
Kozlovcev, Petr; Přikryl, Richard; Racek, Martin; Přikrylová, Jiřina
2016-04-01
In contrast to modern process of production of cement clinker, traditional burning of natural hydraulic lime below sintering temperature relied on the formation of new phases from ion migration between neighbouring mineral grains composing raw material. The importance of the mineralogical composition and spatial distribution of rock-forming minerals in impure limestones used as a raw material for natural hydraulic lime presents not well explored issue in the scientific literature. To fill this gap, the recent study focuses in detailed analysis of experimentally burnt impure limestones (mostly from Barrandian area, Bohemian Massif). The phase changes were documented by optical microscopy, X-ray diffraction, and scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS) coupled with x-ray elemental mapping. The latest allowed for visualization of distribution of elements within raw materials and burnt products. SEM/EDS study brought valuable data on the presence of transitional and/or minor phases, which were poorly detectable by other methods.
Energy Technology Data Exchange (ETDEWEB)
Kalin, J., E-mail: jan.kalin@zag.s [Slovenian National Building and Civil Engineering Institute, Dimiceva 12, SI-1000 Ljubljana (Slovenia); Petkovsek, B., E-mail: borut.petkovsek@zag.s [Slovenian National Building and Civil Engineering Institute, Dimiceva 12, SI-1000 Ljubljana (Slovenia); Montarnal, Ph., E-mail: philippe.montarnal@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Genty, A., E-mail: alain.genty@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Deville, E., E-mail: estelle.deville@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Krivic, J., E-mail: jure.krivic@geo-zs.s [Geological Survey of Slovenia, Dimiceva 14, SI-1000 Ljubljana (Slovenia); Ratej, J., E-mail: joze.ratej@geo-zs.s [Geological Survey of Slovenia, Dimiceva 14, SI-1000 Ljubljana (Slovenia)
2011-04-15
In the past years the Slovenian Performance Analysis/Safety Assessment team has performed many generic studies for the future Slovenian low and intermediate level waste repository, most recently a Special Safety Analysis for the Krsko site. The modelling approach was to split the problem into three parts: near-field (detailed model of the repository), far-field (i.e., geosphere) and biosphere. In the Special Safety Analysis the code used to perform the near-field calculations was Hydrus2D. Recently the team has begun a cooperation with the French Commisariat al'Energie Atomique/Saclay (CEA/Saclay) and, as a part of this cooperation, began investigations into using the Alliances numerical platform for near-field calculations in order to compare the overall approach and calculated results. The article presents the comparison between these two codes for a silo-type repository that was considered in the Special Safety Analysis. The physical layout and characteristics of the repository are presented and a hydraulic and transport model of the repository is developed and implemented in Alliances. Some analysis of sensitivity to mesh fineness and to simulation timestep has been preformed and is also presented. The compared quantity is the output flux of radionuclides on the boundary of the model. Finally the results from Hydrus2D and Alliances are compared and the differences and similarities are commented.
Carli, S.; Bonifetto, R.; Savoldi, L.; Zanino, R.
2015-09-01
A model based on Artificial Neural Networks (ANNs) is developed for the heated line portion of a cryogenic circuit, where supercritical helium (SHe) flows and that also includes a cold circulator, valves, pipes/cryolines and heat exchangers between the main loop and a saturated liquid helium (LHe) bath. The heated line mimics the heat load coming from the superconducting magnets to their cryogenic cooling circuits during the operation of a tokamak fusion reactor. An ANN is trained, using the output from simulations of the circuit performed with the 4C thermal-hydraulic (TH) code, to reproduce the dynamic behavior of the heated line, including for the first time also scenarios where different types of controls act on the circuit. The ANN is then implemented in the 4C circuit model as a new component, which substitutes the original 4C heated line model. For different operational scenarios and control strategies, a good agreement is shown between the simplified ANN model results and the original 4C results, as well as with experimental data from the HELIOS facility confirming the suitability of this new approach which, extended to an entire magnet systems, can lead to real-time control of the cooling loops and fast assessment of control strategies for heat load smoothing to the cryoplant.
Vitillo, F.; Vitale Di Maio, D.; Galati, C.; Caruso, G.
2015-11-01
A CFD analysis has been carried out to study the thermal-hydraulic behavior of liquid metal coolant in a fuel assembly of triangular lattice. In order to obtain fast and accurate results, the isotropic two-equation RANS approach is often used in nuclear engineering applications. A different approach is provided by Non-Linear Eddy Viscosity Models (NLEVM), which try to take into account anisotropic effects by a nonlinear formulation of the Reynolds stress tensor. This approach is very promising, as it results in a very good numerical behavior and in a potentially better fluid flow description than classical isotropic models. An Anisotropic Shear Stress Transport (ASST) model, implemented into a commercial software, has been applied in previous studies, showing very trustful results for a large variety of flows and applications. In the paper, the ASST model has been used to perform an analysis of the fluid flow inside the fuel assembly of the ALFRED lead cooled fast reactor. Then, a comparison between the results of wall-resolved conjugated heat transfer computations and the results of a decoupled analysis using a suitable thermal wall-function previously implemented into the solver has been performed and presented.
New P3D Hydraulic Fracturing Model Based on the Radial Flow
Institute of Scientific and Technical Information of China (English)
鲁连军; 孙逢春; 肖海华; 安申法
2004-01-01
Pseudo three-dimension (P3D) hydraulic fracturing models often overpredict the fracture height for a poorly contained fracture. To solve this problem, a new method is presented in shaping the P3D fracture geometry on the basis of the fundamental theory and the original 1D fluid flow is replaced with a more representatively radial flow. The distribution of the fluid in the modified fluid field is analyzed and a sound explanation to the problem is given. Due to the consideration of the fluid flow in the vertical direction, the modified model can predict the fracture height much better. To validate the rationality of the radial fluid flow assumption, the distribution of the fluid in the modified fluid field is simulated with the plane potential flow by using finite element method. And the results agree effectively with those from the assumption. Through comparing with the full 3D model, the results show that this new P3D model can be used to aid the fracturing design and predict the fracture height under poorly contained situation.
XFEM modeling of hydraulic fracture in porous rocks with natural fractures
Wang, Tao; Liu, ZhanLi; Zeng, QingLei; Gao, Yue; Zhuang, Zhuo
2017-08-01
Hydraulic fracture (HF) in porous rocks is a complex multi-physics coupling process which involves fluid flow, diffusion and solid deformation. In this paper, the extended finite element method (XFEM) coupling with Biot theory is developed to study the HF in permeable rocks with natural fractures (NFs). In the recent XFEM based computational HF models, the fluid flow in fractures and interstitials of the porous media are mostly solved separately, which brings difficulties in dealing with complex fracture morphology. In our new model the fluid flow is solved in a unified framework by considering the fractures as a kind of special porous media and introducing Poiseuille-type flow inside them instead of Darcy-type flow. The most advantage is that it is very convenient to deal with fluid flow inside the complex fracture network, which is important in shale gas extraction. The weak formulation for the new coupled model is derived based on virtual work principle, which includes the XFEM formulation for multiple fractures and fractures intersection in porous media and finite element formulation for the unified fluid flow. Then the plane strain Kristianovic-Geertsma-de Klerk (KGD) model and the fluid flow inside the fracture network are simulated to validate the accuracy and applicability of this method. The numerical results show that large injection rate, low rock permeability and isotropic in-situ stresses tend to lead to a more uniform and productive fracture network.
El-Seddik, Mostafa M; Galal, Mona M; Radwan, A G; Abdel-Halim, Hisham S
2016-01-01
This paper addresses a modified kinetic-hydraulic model for up-flow anaerobic sludge blanket (UASB) reactor aimed to treat wastewater of biodegradable organic substrates as acetic acid based on Van der Meer model incorporated with biological granules inclusion. This dynamic model illustrates the biomass kinetic reaction rate for both direct and indirect growth of microorganisms coupled with the amount of biogas produced by methanogenic bacteria in bed and blanket zones of reactor. Moreover, the pH value required for substrate degradation at the peak specific growth rate of bacteria is discussed for Andrews' kinetics. The sensitivity analyses of biomass concentration with respect to fraction of volume of reactor occupied by granules and up-flow velocity are also demonstrated. Furthermore, the modified mass balance equations of reactor are applied during steady state using Newton Raphson technique to obtain a suitable degree of freedom for the modified model matching with the measured results of UASB Sanhour wastewater treatment plant in Fayoum, Egypt.
Thermal-hydraulic modeling of the Pennsylvania State University Breazeale Nuclear Reactor (PSBR)
Chang, Jong E.
2005-11-01
Earlier experiments determined that the Pennsylvania State University Breazeale Nuclear Reactor (PSBR) core is cooled, not by an axial flow, but rather by a strong cross flow due to the thermal expansion of the coolant. To further complicate the flow field, a nitrogen-16 (N-16) pump was installed above the PSBR core to mix the exiting core buoyant thermal plume in order to delay the rapid release of radioactive N-16 to the PSBR pool surface. Thus, the interaction between the N-16 jet flow and the buoyancy driven flow complicates the analysis of the flow distribution in the PSBR pool. The main objectives of this study is to model the thermal-hydraulic behavior of the PSBR core and pool. During this study four major things were performed including the Computational Fluid Dynamics (CFD) model for the PSBR pool, the stand-alone fuel rod model for a PSBR fuel rod, the velocity measurements in and around the PSBR core, and the temperature measurements in the PSBR pool. Once the flow field was predicted by the CFD model, the measurement devices were manufactured and calibrated based on the CFD results. The major contribution of this study is to understand and to explain the flow behavior in the PSBR subchannels and pool using the FLOW3D model. The stand-alone dynamic fuel rod model was developed to determine the temperature distribution inside a PSBR fuel rod. The stand-alone fuel rod model was coupled to the FLOW3D model and used to predict the temperature behavior during steady-state and pulsing. The heat transfer models in the stand-alone fuel rod code are used in order to overcome the disadvantage of the CFD code, which does not calculate the mechanical stress, the gap conductance, and the two phase heat transfer. (Abstract shortened by UMI.)
Directory of Open Access Journals (Sweden)
Rafael Garcia-Lorenzo
2010-11-01
Full Text Available This paper shows the combined use of remotely sensed data and hydraulic geometry methods as an alternative to rainfall-runoff models. Hydraulic geometric data and boolean images of water sheets obtained from satellite images after storm events were integrated in a Geographical Information System. Channel cross-sections were extracted from a high resolution Digital Terrain Model (DTM and superimposed on the image cover to estimate the peak flow using HEC-RAS. The proposed methodology has been tested in ephemeral channels (ramblas on the coastal zone in south-eastern Spain. These fluvial systems constitute an important natural hazard due to their high discharges and sediment loads. In particular, different areas affected by floods during the period 1997 to 2009 were delimited through HEC-GeoRAs from hydraulic geometry data and Landsat images of these floods (Landsat‑TM5 and Landsat-ETM+7. Such an approach has been validated against rainfall-surface runoff models (SCS Dimensionless Unit Hydrograph, SCSD, Témez gamma HU Tγ and the Modified Rational method, MRM comparing their results with flood hydrographs of the Automatic Hydrologic Information System (AHIS in several ephemeral channels in the Murcia Region. The results obtained from the method providing a better fit were used to calculate different hydraulic geometry parameters, especially in residual flood areas.
Energy Technology Data Exchange (ETDEWEB)
NONE
2011-07-01
Within the VDI/VDE conference at 13th-14th September, 2011 in Stuttgart (Federal Republic of Germany) the following lectures and posters were presented: (1) Sieve printed windings of rotating small drives and their evaluation (P. Braeuer); (2) Variable impedance induction motor - Measurement results of a variable impedance induction motor prototype (H. Gholizad); (3) Utilization of a multiphase winding in a star-polygon hybrid circuit for squirrel asynchronous motors for increasing the energy efficiency - generation of flooding waves of a 6-phase machine with a 3-phase connection (T. Knopik); (4) Virtual development of electric moors - Design of an asynchronous motor for propel drives by means of a numeric optimization and software automation (V. Reinhardt); (5) A hybrid microproduction system driven by piezoactuators and linear motors (C. Hast); (6) MRF actors with minimized standby losses (D. Gueth); (7) Experimental determination of rotor losses in a homopolar magnetic bearing (E. Fleischer); (8) Vibrational condition monitoring of coiler heads of electric large machines (C. Kreischer); (9) Recovery potentials in the electric propulsion technology - ''What is left usable from the energy'' (M. Schumacher); (10) Overall energy balance in the powertrain - The application decides - Energetic analysis of a powertrain (A. Thomas); (11) Optimal dimensioning of an actuator in the mechatronic overall system electric motor - gear - load (M. Lindner); (12) Electric and hydraulic hybrid actuator: Competing and complementary systems (K. Dehnert); (13) Intelligent pump drives - Simulation, condition monitoring, fault diagnosis and energy efficiency (S. Kleinmann); (14) Parametric models of the permanent magnet-synchronous machine (PMSM) under consideration of the impacts of magnetic saturation (F. Mink); (15) Electromagnetic, structure dynamic acoustic FEM simulation of an asynchronous motor for the evaluation of noise emission (J. Wibbeler); (16
Chen, Sheng-Hong
2015-01-01
This book discusses in detail the planning, design, construction and management of hydraulic structures, covering dams, spillways, tunnels, cut slopes, sluices, water intake and measuring works, ship locks and lifts, as well as fish ways. Particular attention is paid to considerations concerning the environment, hydrology, geology and materials etc. in the planning and design of hydraulic projects. It also considers the type selection, profile configuration, stress/stability calibration and engineering countermeasures, flood releasing arrangements and scouring protection, operation and maintenance etc. for a variety of specific hydraulic structures. The book is primarily intended for engineers, undergraduate and graduate students in the field of civil and hydraulic engineering who are faced with the challenges of extending our understanding of hydraulic structures ranging from traditional to groundbreaking, as well as designing, constructing and managing safe, durable hydraulic structures that are economical ...
Vibration of hydraulic machinery
Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong
2013-01-01
Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...
Wiegand, D.E.
1962-05-01
A hydraulic servo is designed in which a small pressure difference produced at two orifices by an electrically operated flapper arm in a constantly flowing hydraulic loop is hydraulically amplified by two constant flow pumps, two additional orifices, and three unconnected ball pistons. Two of the pistons are of one size and operate against the additional orifices, and the third piston is of a different size and operates between and against the first two pistons. (AEC)
Inconsistency in the average hydraulic models used in nuclear reactor design and safety analysis
Energy Technology Data Exchange (ETDEWEB)
Park, Jee Won; Roh, Gyu Hong; Choi, Hang Bok [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1997-12-31
One of important inconsistencies in the six-equation model predictions has been found to be the force experienced by a single bubble placed in a convergent stream of liquid. Various sets of governing equations yield different amount of forces to hold the bubble stationary in a convergent nozzle. By using the first order potential flow theory, it is found that the six-equation model can not be used to estimate the force experienced by a deformed bubble. The theoretical value of the particle stress of a bubble in a convergent nozzle flow has been found to be a function of the Weber number when bubble distortion is allowed. This force has been calculated by using different sets of governing equations and compared with the theoretical value. It is suggested in this study that the bubble size distribution function can be used to remove the presented inconsistency by relating the interfacial variables with different moments of the bubble size distribution function. This study also shows that the inconsistencies in the thermal-hydraulic governing equation can be removed by mechanistic modeling of the phasic interface. 11 refs., 3 figs. (Author)
Couvreur, Valentin; Kandelous, Maziar; Mairesse, Harmony; Baram, Shahar; Moradi, Ahmad; Pope, Katrin; Hopmans, Jan
2015-04-01
Groundwater quality is specifically vulnerable in irrigated agricultural lands in California and many other (semi-)arid regions of the world. The routine application of nitrogen fertilizers with irrigation water in California is likely responsible for the high nitrate concentrations in groundwater, underlying much of its main agricultural areas. To optimize irrigation/fertigation practices, it is essential that irrigation and fertilizers are applied at the optimal concentration, place, and time to ensure maximum root uptake and minimize leaching losses to the groundwater. The applied irrigation water and dissolved fertilizer, root nitrate and water uptake interact with soil and root properties in a complex manner that cannot easily be resolved. It is therefore that coupled experimental-modelling studies are required to allow for unravelling of the relevant complexities that result from typical variations of crop properties, soil texture and layering across farmer-managed fields. A combined field monitoring and modelling approach was developed to quantify from simple measurements the leaching of water and nitrate below the root zone. The monitored state variables are soil water content within the root zone, soil matric potential below the root zone, and nitrate concentration in the soil solution. Plant and soil properties of incremented complexity are optimized with the software HYDRUS in an inverse modelling scheme, which allows estimating leaching under constraint of hydraulic principles. Questions of optimal irrigation and fertilization timing can then be addressed using predictive results and global optimization algorithms.
Modeling Air Bubble Transport in Hydraulic Jump Flows using Population Balance Approach
Directory of Open Access Journals (Sweden)
Min Xiang
2016-01-01
Full Text Available This paper proposed a numerical model aiming at coupling the MUltiple-SIze-Group (MUSIG with the semiempirical air entrainment model based on the Euler-Euler two-fluid framework to handle the bubble transport in hydraulic jump flows. The internal flow structure including the recirculation region, the shear layer region and the jet region was accurately predicted. The flow parameters such as the water velocity and void fraction distributions were examined and compared with the experimental data, validating the effectiveness of the numerical model. Prediction of the Sauter mean bubble diameter distributions by the population balance approach at different axial locations confirmed the dominance of breakage due to the high turbulent intensity in the shear layer region which led to the generation of small gas bubbles at high void fraction. Comparison between different cases indicates that high Froude number not only give rise to longer recirculation region and higher void fraction due to larger air entrainment rate, but also generate larger bubble number density and smaller bubble size because of the stronger turbulence intensity in the same axial position.
MyrrhaFoam: A CFD model for the study of the thermal hydraulic behavior of MYRRHA
Energy Technology Data Exchange (ETDEWEB)
Koloszar, Lilla; Buckingham, Sophia; Planquart, Philippe [von Karman Institute, Chaussée de Waterloo 72, B-1640 Rhode-St-Genèse (Belgium); Keijers, Steven [SCK-CEN, Boeretang 200, 2400 Mol (Belgium)
2017-02-15
Highlights: • Development of a modeling approach for simulating the thermal hydraulics of heavy liquid metal nuclear reactors. • Detailed description of the modeling of each component through the MYRRHA reactor. • Detailed analysis of the flow field of the MYRRHA reactor under operating condition. • Assessment of the thermal load on the structures as well as the thermal stratification in the upper and the lower plenum. - Abstract: Numerical analysis of the thermohydraulic behavior of the innovative flexible fast spectrum research reactor, MYRRHA, under design by the Belgian Nuclear Research Center (SCK• CEN) is a very challenging task. The primary coolant of the reactor is Lead Bismuth Eutectic, LBE, which is an opaque heavy liquid metal with low Prandtl number. The simulation tool needs to involve many complex physical phenomena to be able to predict accurately the flow and thermal field in the pool type reactor. In the past few years, within the frame of a collaboration between SCK• CEN and the von Karman Institute, a new platform, MyrrhaFoam, was developed based on the open source simulation environment, OpenFOAM. The current tool can deal with incompressible buoyancy corrected steady/unsteady single phase flows. It takes into account conjugate heat transfer in the solid parts which is mandatory due to the expected high temperature gradients between the different parts of the reactor. The temperature dependent properties of LBE are also considered. MyrrhaFoam is supplemented with the most relevant thermal turbulence models for low Prandtl number liquids up to date.
Flood Hazard Mapping using Hydraulic Model and GIS: A Case Study in Mandalay City, Myanmar
Directory of Open Access Journals (Sweden)
Kyu Kyu Sein
2016-01-01
Full Text Available This paper presents the use of flood frequency analysis integrating with 1D Hydraulic model (HECRAS and Geographic Information System (GIS to prepare flood hazard maps of different return periods in Ayeyarwady River at Mandalay City in Myanmar. Gumbel’s distribution was used to calculate the flood peak of different return periods, namely, 10 years, 20 years, 50 years, and 100 years. The flood peak from frequency analysis were input into HEC-RAS model to find the corresponding flood level and extents in the study area. The model results were used in integrating with ArcGIS to generate flood plain maps. Flood depths and extents have been identified through flood plain maps. Analysis of 100 years return period flood plain map indicated that 157.88 km2 with the percentage of 17.54% is likely to be inundated. The predicted flood depth ranges varies from greater than 0 to 24 m in the flood plains and on the river. The range between 3 to 5 m were identified in the urban area of Chanayetharzan, Patheingyi, and Amarapua Townships. The highest inundated area was 85 km2 in the Amarapura Township.
Thomas, R. E.; Simon, A.; Bankhead, N.
2008-12-01
Physically-based, deterministic bank-stability models have recently been developed to effectively simulate the driving and resisting forces governing streambank erosion. Significant advances have been made in the manner in which groundwater flow through variably saturated porous media, planar and circular geotechnical failures and fluvial sediment transport are simulated. However, to date, coupling these models has required tedious exporting and conversion of geometries and results and manual remeshing. In this presentation, we introduce the first fully integrated suite of models that deterministically simulate the controlling hydrologic, hydraulic and geotechnical processes that govern streambank erosion and channel-width adjustment. The model suite incorporates routines that: 1. Permit the user to enter between 5 and 23 points to describe the bank cross-sectional geometry; 2. Automatically generate a mesh by which to implicitly discretize the 2-D Richards equation utilizing finite volumes. The resulting pentadiagonal matrix is solved iteratively with Stone's Strongly Implicit Procedure (SIP). Timesteps are automatically adjusted to minimize mass balance and truncation errors; 3. Evaluate the force-equilibrium factor of safety (Fs), permitting the simulation of planar and cantilever shear failures with a horizontal slice method and planar shear failures with tension cracks with a rigorous vertical slice method. A random walk approach is adopted to search for the minimum Fs; 4. Estimate the increase in cohesion due to vegetation with a global load-sharing Fibre Bundle Model; and 5. Simulate the erosion of the bank face and bank toe with an excess shear stress approach. Management options to increase slope stability (through the addition of vegetation) and reduce channel- boundary erodibility (through the addition of natural and artificial structures) are also incorporated. We illustrate the efficacy of the modeling approach with a series of case studies in which
Zimmer, A. L.; Minsker, B. S.; Schmidt, A. R.; Ostfeld, A.
2011-12-01
Real-time mitigation of combined sewer overflows (CSOs) requires evaluation of multiple operational strategies during rapidly changing rainfall events. Simulation models for hydraulically complex systems can effectively provide decision support for short time intervals when coupled with efficient optimization. This work seeks to reduce CSOs for a test case roughly based on the North Branch of the Chicago Tunnel and Reservoir Plan (TARP), which is operated by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC). The North Branch tunnel flows to a junction with the main TARP system. The Chicago combined sewer system alleviates potential CSOs by directing high interceptor flows through sluice gates and dropshafts to a deep tunnel. Decision variables to control CSOs consist of sluice gate positions that control water flow to the tunnel as well as a treatment plant pumping rate that lowers interceptor water levels. A physics-based numerical model is used to simulate the hydraulic effects of changes in the decision variables. The numerical model is step-wise steady and conserves water mass and momentum at each time step by iterating through a series of look-up tables. The look-up tables are constructed offline to avoid extensive real-time calculations, and describe conduit storage and water elevations as a function of flow. A genetic algorithm (GA) is used to minimize CSOs at each time interval within a moving horizon framework. Decision variables are coded at 15-minute increments and GA solutions are two hours in duration. At each 15-minute interval, the algorithm identifies a good solution for a two-hour rainfall forecast. Three GA modifications help reduce optimization time. The first adjustment reduces the search alphabet by eliminating sluice gate positions that do not influence overflow volume. The second GA retains knowledge of the best decision at the previous interval by shifting the genes in the best previous sequence to initialize search at
Gayler, Sebastian; Salima-Sultana, Daisy; Selle, Benny; Ingwersen, Joachim; Wizemann, Hans-Dieter; Högy, Petra; Streck, Thilo
2016-04-01
Soil water extraction by roots affects the dynamics and distribution of soil moisture and controls transpiration, which influences soil-vegetation-atmosphere feedback processes. Consequently, root water uptake requires close attention when predicting water fluxes across the land surface, e.g., in agricultural crop models or in land surface schemes of weather and climate models. The key parameters for a successful simultaneous simulation of soil moisture dynamics and evapotranspiration in Richards equation-based models are the soil hydraulic parameters, which describe the shapes of the soil water retention curve and the soil hydraulic conductivity curve. As measurements of these parameters are expensive and their estimation from basic soil data via pedotransfer functions is rather inaccurate, the values of the soil hydraulic parameters are frequently inversely estimated by fitting the model to measured time series of soil water content and evapotranspiration. It is common to simulate root water uptake and transpiration by simple stress functions, which describe from which soil layer water is absorbed by roots and predict when total crop transpiration is decreased in case of soil water limitations. As for most of the biogeophysical processes simulated in crop and land surface models, there exist several alternative functional relationships for simulating root water uptake and there is no clear reason for preferring one process representation over another. The error associated with alternative representations of root water uptake, however, contributes to structural model uncertainty and the choice of the root water uptake model may have a significant impact on the values of the soil hydraulic parameters estimated inversely. In this study, we use the agroecosystem model system Expert-N to simulate soil moisture dynamics and evapotranspiration at three agricultural field sites located in two contrasting regions in Southwest Germany (Kraichgau, Swabian Alb). The Richards
Urban micro-scale flood risk estimation with parsimonious hydraulic modelling and census data
Directory of Open Access Journals (Sweden)
C. Arrighi
2013-05-01
Full Text Available The adoption of 2007/60/EC Directive requires European countries to implement flood hazard and flood risk maps by the end of 2013. Flood risk is the product of flood hazard, vulnerability and exposure, all three to be estimated with comparable level of accuracy. The route to flood risk assessment is consequently much more than hydraulic modelling of inundation, that is hazard mapping. While hazard maps have already been implemented in many countries, quantitative damage and risk maps are still at a preliminary level. A parsimonious quasi-2-D hydraulic model is here adopted, having many advantages in terms of easy set-up. It is here evaluated as being accurate in flood depth estimation in urban areas with a high-resolution and up-to-date Digital Surface Model (DSM. The accuracy, estimated by comparison with marble-plate records of a historic flood in the city of Florence, is characterized in the downtown's most flooded area by a bias of a very few centimetres and a determination coefficient of 0.73. The average risk is found to be about 14 € m−2 yr−1, corresponding to about 8.3% of residents' income. The spatial distribution of estimated risk highlights a complex interaction between the flood pattern and the building characteristics. As a final example application, the estimated risk values have been used to compare different retrofitting measures. Proceeding through the risk estimation steps, a new micro-scale potential damage assessment method is proposed. This is based on the georeferenced census system as the optimal compromise between spatial detail and open availability of socio-economic data. The results of flood risk assessment at the census section scale resolve most of the risk spatial variability, and they can be easily aggregated to whatever upper scale is needed given that they are geographically defined as contiguous polygons. Damage is calculated through stage–damage curves, starting from census data on building type and
Energy Technology Data Exchange (ETDEWEB)
Dudley, Trevor [Pebble Bed Modular Reactor (Proprietary) Limited, Die Anker Building, Centurion 0046 (South Africa)], E-mail: trevor.dudley@pbmr.co.za; Bouwer, Werner; Villiers, Piet de [Pebble Bed Modular Reactor (Proprietary) Limited, Die Anker Building, Centurion 0046 (South Africa); Wang Zen [GSE Systems, Inc., 7133 Rutherford Suite 200, Baltimore, MD 21244 (United States)
2008-11-15
This paper provides a discussion of the model development status and verification efforts for the Reactor Core Thermal-Hydraulic model developed for the full-scope plant Operator Training Simulator System of the Pebble Bed Modular Reactor (PBMR). Due to the First of a Kind Engineering nature and lack of reference plant data, model verification has mainly been focused on benchmarking the model configurations against test cases performed by PBMR design analysis codes, i.e. TINTE, VSOP and FLOWNEX. As a first step, due to the symmetrical physical nature of the PBMR core, a two-dimensional (2D) model configuration in radial and axial directions (axial-symmetry) was developed. The design was subsequently extended to a three-dimensional (3D) configuration. Through the use of cross-flow and cross-conduction links, three nearly identical 2D configurations were glued together to form this 3D model configuration. To date, the 3D configuration represents the most comprehensive model to simulate the PBMR core thermo-hydraulics. This paper concludes with the verification of thermodynamic and heat-transfer properties of two steady state (100% and 40% power) conditions between the 3D Reactor Core Thermal-Hydraulic model and the available FLOWNEX and TINTE design code analysis. The transient operations between these two power levels are also discussed.
Hosseiny, S. M. H.; Zarzar, C.; Gomez, M.; Siddique, R.; Smith, V.; Mejia, A.; Demir, I.
2016-12-01
The National Water Model (NWM) provides a platform for operationalize nationwide flood inundation forecasting and mapping. The ability to model flood inundation on a national scale will provide invaluable information to decision makers and local emergency officials. Often, forecast products use deterministic model output to provide a visual representation of a single inundation scenario, which is subject to uncertainty from various sources. While this provides a straightforward representation of the potential inundation, the inherent uncertainty associated with the model output should be considered to optimize this tool for decision making support. The goal of this study is to produce ensembles of future flood inundation conditions (i.e. extent, depth, and velocity) to spatially quantify and visually assess uncertainties associated with the predicted flood inundation maps. The setting for this study is located in a highly urbanized watershed along the Darby Creek in Pennsylvania. A forecasting framework coupling the NWM with multiple hydraulic models was developed to produce a suite ensembles of future flood inundation predictions. Time lagged ensembles from the NWM short range forecasts were used to account for uncertainty associated with the hydrologic forecasts. The forecasts from the NWM were input to iRIC and HEC-RAS two-dimensional software packages, from which water extent, depth, and flow velocity were output. Quantifying the agreement between output ensembles for each forecast grid provided the uncertainty metrics for predicted flood water inundation extent, depth, and flow velocity. For visualization, a series of flood maps that display flood extent, water depth, and flow velocity along with the underlying uncertainty associated with each of the forecasted variables were produced. The results from this study demonstrate the potential to incorporate and visualize model uncertainties in flood inundation maps in order to identify the high flood risk zones.
Baroni, G.; Facchi, A.; Gandolfi, C.; Ortuani, B.; Horeschi, D.; Dam, van J.C.
2010-01-01
Data of soil hydraulic properties forms often a limiting factor in unsaturated zone modelling, especially at the larger scales. Investigations for the hydraulic characterization of soils are time-consuming and costly, and the accuracy of the results obtained by the different methodologies is still d
Baroni, G.; Facchi, A.; Gandolfi, C.; Ortuani, B.; Horeschi, D.; Dam, van J.C.
2010-01-01
Data of soil hydraulic properties forms often a limiting factor in unsaturated zone modelling, especially at the larger scales. Investigations for the hydraulic characterization of soils are time-consuming and costly, and the accuracy of the results obtained by the different methodologies is still
The Laser Scan Data as a Key Element in the Hydraulic Flood Modelling in Urban Areas
Sole, A.; Giosa, L.; Albano, R.; Cantisani, A.
2013-05-01
This paper is intended to highlight the need to use data at high spatial resolution, such as those obtained through the use of Airborne Laser Scanning (ALS) techniques, to support hydraulic models for the assessment of flood hazards in urban territory. In fact, the significant structural features (houses, walls, roads, etc.) in the city are important in relation to both the volume of the floodplain that can be occupied by the flow and the direction that the flow takes across the floodplain. ALS data can range up to several terabytes in size and is a function of the geographic scale of the mission. Also, this data is typically irregular with uneven point density. Therefore, a quick method is described to ride out the difficulties to handle the large datasets with uneven point densities and to improve the extracting of feature information for further use in Geographic Information System (GIS) analysis. Finally, a comparison is made between the maximum inundated area obtained from ALS data and that one calculated using a traditional topographic map. The results show that the high-resolution data obtained from airborne remote sensing can increase the opportunities for representation of small-scale structural elements in complex systems using two-dimensional models of flood inundation.
Yushi, Zou; Xinfang, Ma; Tong, Zhou; Ning, Li; Ming, Chen; Sihai, Li; Yinuo, Zhang; Han, Li
2017-09-01
Hydraulic fracture (HF) height containment tends to occur in layered formations, and it significantly influences the entire HF geometry or the stimulated reservoir volume. This study aims to explore the influence of preexisting bedding planes (BPs) on the HF height growth in layered formations. Laboratory fracturing experiments were performed to confirm the occurrence of HF height containment in natural shale that contains multiple weak and high-permeability BPs under triaxial stresses. Numerical simulations were then conducted to further illustrate the manner in which vertical stress, BP permeability, BP density(or spacing), pump rate, and fluid viscosity control HF height growth using a 3D discrete element method-based fracturing model. In this model, the rock matrix was considered transversely isotropic and multiple BPs can be explicitly represented. Experimental and numerical results show that the vertically growing HF tends to be limited by multi-high-permeability BPs, even under higher vertical stress. When the vertically growing HF intersects with the multi-high-permeability BPs, the injection pressure will be sharply reduced. If a low pumping rate or a low-viscosity fluid is used, the excess fracturing fluid leak-off into the BPs obviously decreases the rate of pressure build up, which will then limit the growth of HF. Otherwise, a higher pumping rate and/or a higher viscosity will reduce the leak-off time and fluid volume, but increase the injection pressure to drive the HF to grow and to penetrate through the BPs.
Risk zone of wrack hitting marine structure simulated by 2D hydraulic model
Institute of Scientific and Technical Information of China (English)
MA Jin-rong; GUO Ya-qiong; NAN Wei
2010-01-01
The wrack or the ship out of control will drift with flow.One of the most important factors that drive the ship is flow current which moves circularly in tidal area.The wrack from same place always drifts in different ways if the start time is different.So,during the ship drifting period,the drift trace is also determined by both wave and wind forces.The drift direction is limited by water depth which must be deeper than ship draft.These marine structures that can not afford the hit of wrack or will destroy the wrack must be well considered when they are placed near harbor and waterway or other water area with ship running.The risk zone should be consulted according to tide and weather conditions to protect structures and ships in necessary.A method is presented here to simulate the risk zone by 2D numerical hydraulic model with tidal current,wave,wind and water depth considered.This model can be used to built early-warning and protect system for special maline structure.
Energy Technology Data Exchange (ETDEWEB)
Chae, Hee Taek; Park, Jong Hark; Park, Cheol
2006-11-15
A new research reactor (AHR, Advanced HANARO Reactor) based on the HANARO has being conceptually developed for the future needs of research reactors. A tubular type fuel was considered as one of the fuel options of the AHR. A tubular type fuel assembly has several curved fuel plates arranged with a constant small gap to build up cooling channels, which is very similar to an annulus pipe with many layers. This report presents the preliminary analysis of thermal hydraulic characteristics and safety margins for three conceptual core models using tubular fuel assemblies. Four design criteria, which are the fuel temperature, ONB (Onset of Nucleate Boiling) margin, minimum DNBR (Departure from Nucleate Boiling Ratio) and OFIR (Onset of Flow Instability Ratio), were investigated along with various core flow velocities in the normal operating conditions. And the primary coolant flow rate based a conceptual core model was suggested as a design information for the process design of the primary cooling system. The computational fluid dynamics analysis was also carried out to evaluate the coolant velocity distributions between tubular channels and the pressure drop characteristics of the tubular fuel assembly.
Hydrogeological model and hydraulic behaviour of a large landslide in the Italian Western Alps
Directory of Open Access Journals (Sweden)
G. Pisani
2010-11-01
Full Text Available A study of the large, deep-seated Rosone landslide (Italian Western Alps is presented. A large amount of geological and geomechanical data has been collected in this area, due to the presence of various villages and man-made structures, and an automatic monitoring system was installed in December 2000. Since its installation, this system has been showing a continuous slow movement with periodical accelerations that can be correlated to heavy rainfall events. A hydrogeological model has been developed to study the influence of rainfall events on the pore pressure variations inside the rock slope. The structural characteristics, inclinometric and piezometric measurements, statigraphic and seismic profiles, geomorphologic information, water balance and chemical analyses of the main springs in the slope have been taken into account to consider this problem. A numerical hydraulic investigation, based on a continuum equivalent model of the landslide, has then been carried out using the FLAC^{3D} computer code. Some preliminary results, which highlight the role of permeability and the porosity values of the rock mass on the pore pressure variations during heavy rainfall, are shown in the paper.
Zehe, E.; Becker, R.; Schädel, W.
A dynamic system left without external disturbances, will always tend to a stable equilibrium state that is consistent with the internal physics. For natural soils such an equilibrium state is reached when the gradients of the total hydraulic potential tend to zero. This statement is still valid for heterogeneous soils, because the hydraulic po- tential is an intensive state variable and therefore continuous at discontinuities of the pore space. In contrary the soil water content is as an extensive property discontinu- ous at discontinuities of the pore space. Hence, a small scale soil moisture pattern that persists if the soil state tends to hydraulic equilibrium, reflects the lateral small scale variability of the pore space. The objectives of our study are to show a) whether and how we could use TDR observations to identify the small scale variability of the pore space. For that purpose we analyse artificial TDR measurements, taken from physi- cally based simulations of soil water dynamics in heterogeneous media. b) We want to introduce a new TDR technology which we call "Spatial TDR", that is suitable for that purposes. To produce the artificial TDR-datasets we generate random fields of soil porosity and saturated hydraulic conductivity with different statistical properties based on field data in a Luvisol and simulate artificial water dynamics in this model soil based on Richards-equation. Within this model soil we define several hypothetical "Spatial TDR" clusters, that differ in the lateral spacing and the number of the probes, in the temporal resolution of the hypothetical measurements and in the assumed mea- surement accuracy. If the model soil approaches hydraulic equilibrium, the remaining soil moisture pattern will be dominated by the statistical properties of the porosity. In contrary the variability of the hydraulic conductivity will dominate the soil moisture patterns during infiltration events. The hypothetical Spatial TDR measurements within the
Modelling of a hydraulic engine mount with fluid-structure interaction finite element analysis
Shangguan, Wen-Bin; Lu, Zhen-Hua
2004-08-01
Hydraulic engine mount (HEM) is now widely used as a highly effective vibration isolator in automotive powertrain. A lumped parameter (LP) model is a traditional model for modelling the dynamic characteristics of HEM, in which the system parameters are usually obtained by experiments. In this paper, a fluid-structure interaction (FSI) finite element analysis (FEA) method and a non-linear FEA technology are used to determine the system parameters, and a fully coupled FSI model is developed for modelling the static and lower-frequency performance of an HEM. A FSI FEA technique is used to estimate the parameters of volumetric compliances, equivalent piston area, inertia and resistance of the fluid in the inertia track and the decoupler of an HEM. A non-linear FEA method is applied to determine the dynamic stiffness of rubber spring of the HEM. The system parameters predicated by FEA are compared favorably with experimental data and/or analytical solutions. A numerical simulation for an HEM with an inertia track and a free decoupler is performed based on the FSI model and the LP model along with the estimated system parameters, and again the simulation results are compared with experimental data. The calculated time histories of some variables in the model, such as the pressure in the upper chamber, the displacement of the free decoupler and the volume flow through the inertia track and the decoupler, under different excitations, elucidate the working mechanism of the HEM. The pressure distribution calculated with the FSI model in the chambers of the HEM validates the assumption that the pressure distribution in the upper and lower chamber is uniform in the LP model. The work conducted in the paper demonstrates that the methods for estimating the system parameters in the LP model and the FSI model for modelling HEM are effective, with which the dynamic characteristic analysis and design optimization of an HEM can be performed before its prototype development, and this
A New Physics-Based Modeling of Multiple Non-Planar Hydraulic Fractures Propagation
Energy Technology Data Exchange (ETDEWEB)
Zhou, Jing [University of Utah; Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States); Deo, Milind [University of Utah; Jiang, Shu [Energy & Geoscience Institute
2015-10-01
Because of the low permeability in shale plays, closely spaced hydraulic fractures and multilateral horizontal wells are generally required to improve production. Therefore, understanding the potential fracture interaction and stress evolution is critical in optimizing fracture/well design and completion strategy in multi-stage horizontal wells. In this paper, a novel fully coupled reservoir flow and geomechanics model based on the dual-lattice system is developed to simulate multiple non-planar fractures propagation. The numerical model from Discrete Element Method (DEM) is used to simulate the mechanics of fracture propagations and interactions, while a conjugate irregular lattice network is generated to represent fluid flow in both fractures and formation. The fluid flow in the formation is controlled by Darcy’s law, but within fractures it is simulated by using cubic law for laminar flow through parallel plates. Initiation, growth and coalescence of the microcracks will lead to the generation of macroscopic fractures, which is explicitly mimicked by failure and removal of bonds between particles from the discrete element network. We investigate the fracture propagation path in both homogeneous and heterogeneous reservoirs using the simulator developed. Stress shadow caused by the transverse fracture will change the orientation of principal stress in the fracture neighborhood, which may inhibit or alter the growth direction of nearby fracture clusters. However, the initial in-situ stress anisotropy often helps overcome this phenomenon. Under large in-situ stress anisotropy, the hydraulic fractures are more likely to propagate in a direction that is perpendicular to the minimum horizontal stress. Under small in-situ stress anisotropy, there is a greater chance for fractures from nearby clusters to merge with each other. Then, we examine the differences in fracture geometry caused by fracturing in cemented or uncemented wellbore. Moreover, the impact of
Simulating floods : On the application of a 2D-hydraulic model for flood hazard and risk assessment
Alkema, D.
2007-01-01
Over the last decades, river floods in Europe seem to occur more frequently and are causing more and more economic and emotional damage. Understanding the processes causing flooding and the development of simulation models to evaluate countermeasures to control that damage are important issues. This study deals with the application of a 2D hydraulic flood propagation model for flood hazard and risk assessment. It focuses on two components: 1) how well does it predict the spatial-dynamic chara...
Modeling of power electronic systems with EMTP
Tam, Kwa-Sur; Dravid, Narayan V.
1989-01-01
In view of the potential impact of power electronics on power systems, there is need for a computer modeling/analysis tool to perform simulation studies on power systems with power electronic components as well as to educate engineering students about such systems. The modeling of the major power electronic components of the NASA Space Station Freedom Electric Power System is described along with ElectroMagnetic Transients Program (EMTP) and it is demonstrated that EMTP can serve as a very useful tool for teaching, design, analysis, and research in the area of power systems with power electronic components. EMTP modeling of power electronic circuits is described and simulation results are presented.
Adaptive Control System of Hydraulic Pressure Based on The Mathematical Modeling
Pilipenko, A. V.; Pilipenko, A. P.; Kanatnikov, N. V.
2016-04-01
In this paper, the authors highlight the problem of replacing an old heavy industrial equipment, and offer the replacement of obsolete control systems on the modern adaptive control system, which takes into account changes in the hydraulic system of the press and compensates them with a corrective action. The proposed system can reduce a water hammer and thereby increase the durability of the hydraulic system and tools.
Institute of Scientific and Technical Information of China (English)
张宪宇; 陈小虎; 何庆飞; 万俊盛
2012-01-01
A hydraulic system test-bed was taken as research object, and AMESim was used for simulation analysis. Hie HCD simulation model of the hydraulic system was built. In order to verify the correctness of the model, characteristics simulation was proceeded and compared with physical characteristics. The HCD simulation model was used to analyze the characteristic factors which in- flueneed hydraulic actuator velocity. The quantification contrast curves of hydraulic actuator velocity were gotten, which were influenced by flow, piston diameter, piston rod diameter and leakage. It provides basis for hydraulic system design and fault diagnosis.%以某液压实验台为研究对象,运用AMESim对液压系统进行仿真分析.建立液压系统的HCD仿真模型；进行特性仿真,并与物理特性进行对比,验证了HCD仿真模型的正确性；运用所建立的HCD仿真模型对影响液压缸运动速度的因素进行分析,给出不同的流量、活塞缸直径、活塞杆直径及泄漏影响液压缸运动速度的量化对比曲线,从而为液压系统的设计及故障诊断提供依据.
Directory of Open Access Journals (Sweden)
B. Scharnagl
2011-10-01
Full Text Available In situ observations of soil water state variables under natural boundary conditions are often used to estimate the soil hydraulic properties. However, many contributions to the soil hydrological literature have demonstrated that the information content of such data is insufficient to accurately and precisely estimate all the soil hydraulic parameters. In this case study, we explored to which degree prior information about the soil hydraulic parameters can help improve parameter identifiability in inverse modelling of in situ soil water dynamics under natural boundary conditions. We used percentages of sand, silt, and clay as input variables to the ROSETTA pedotransfer function that predicts the parameters in the van Genuchten-Mualem (VGM model of the soil hydraulic functions. To derive additional information about the correlation structure of the predicted parameters, which is not readily provided by ROSETTA, we employed a Monte Carlo approach. We formulated three prior distributions that incorporate to different extents the prior information about the VGM parameters derived with ROSETTA. The inverse problem was posed in a formal Bayesian framework and solved using Markov chain Monte Carlo (MCMC simulation with the DiffeRential Evolution Adaptive Metropolis (DREAM algorithm. Synthetic and real-world soil water content data were used to illustrate the approach. The results of this study demonstrated that prior information about the soil hydraulic parameters significantly improved parameter identifiability and that this approach was effective and robust, even in case of biased prior information. To be effective and robust, however, it was essential to use a prior distribution that incorporates information about parameter correlation.
Directory of Open Access Journals (Sweden)
Narendra K. Singh
2016-09-01
Full Text Available Rotary hydraulic dashpot used for shut-off rod drive mechanism application of a nuclear reactor has been studied in this paper for impact free operation. The rotary hydraulic dashpot has been modeled as a system with 1 degree of freedom (DOF and the simulation results are experimentally validated. The dashpot is modeled as a hinge joint with moving and fixed vanes as rigid bodies. Shut-off rods are used to shut-down a nuclear reactor and hydraulic dashpot absorbs the energy of freely falling shut-off rod at the end of rod travel. With the increase in the environmental temperature the dashpot becomes underdamped at a point because of reduction in the viscosity of oil and results into impact on mechanism components. Hydraulic dashpot designs are finalized with an optimum combination of dashpot clearances and oil viscosity to meet the drop time criterion and impact free operation at room temperature as well as at elevated temperature. Also with the change in mechanical loads the dashpot becomes underdamped. So the study is further extended to see the effects of various parameters such as moment of inertia, constraint angle and applied moment on the dashpot. Study is focused on obtaining dashpot responses in terms of relative rotation, relative angular velocity and relative angular acceleration at various environmental temperatures. Finite element commercial code COMSOL Multiphysics 5.1 has been used for numerical simulations. Equations for both rigid body dynamics and heat transfer in solids are solved simultaneously. Thus, energy absorbed and local temperature rise in the dashpot operation is also obtained. Both simulation and experimental results at wide range of environmental temperature are presented and compared in this paper. This study forms a good tool to design a hydraulic dashpot, which gives impact free operation in a shut-off rod free fall.
DEFF Research Database (Denmark)
Conrad, Finn
2005-01-01
The paper presents research results using IT-Tools for CAD and dynamic modelling, simulation, analysis, and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. Matlab/Simulink and CATIA are used as IT-Tools. The contributions include results from on......-going research projects on fluid power and mechatronics based on tap water hydraulic servovalves and linear servo actuators and rotary vane actuators for motion control and power transmission. Development and design a novel water hydraulic rotary vane actuator for robot manipulators. Proposed mathematical...... modelling, control and simulation of a water hydraulic rotary vane actuator applied to power and control a two-links manipulator and evaluate performance. The results include engineering design and test of the proposed simulation models compared with IHA Tampere University’s presentation of research...
Indian Academy of Sciences (India)
NEENA ISAAC; T I ELDHO
2017-07-01
Storage capacity of hydropower reservoirs is lost due to sediment deposition. The problem is severe in projects located on rivers with high sediment concentration during the flood season. Removing the sediment deposition hydraulically by drawdown flushing is one of the most effective methods for restoring the storagecapacity. Effectiveness of the flushing depends on various factors, as most of them are site specific. Physical/mathematical models can be effectively used to simulate the flushing operation, and based on the results of the simulation, the layout design and operation schedule of such projects can be modified for better sediment management. This paper presents the drawdown flushing studies of the reservoir of a Himalayan River Hydroelectric Project called Kotlibhel in Uttarakhand, India. For the hydraulic model studies, a 1:100 scale geometrically similar model was constructed. Simulation studies in the model indicated that drawdown flushing for duration of 12 h with a discharge of 500 m3/s or more is effective in removing the annual sediment deposition in the reservoir. The model studies show that the sedimentation problem of the reservoir can be effectively managed through hydraulic flushing.
Computational simulation of thermal hydraulic processes in the model LMFBR fuel assembly
Bayaskhalanov, M. V.; Merinov, I. G.; Korsun, A. S.; Vlasov, M. N.
2017-01-01
The aim of this study was to verify a developed software module on the experimental fuel assembly with partial blockage of the flow section. The developed software module for simulation of thermal hydraulic processes in liquid metal coolant is based on theory of anisotropic porous media with specially developed integral turbulence model for coefficients determination. The finite element method is used for numerical solution. Experimental data for hexahedral assembly with electrically heated smooth cylindrical rods cooled by liquid sodium are considered. The results of calculation obtained with developed software module for a case of corner blockade are presented. The calculated distribution of coolant velocities showed the presence of the vortex flow behind the blockade. Features vortex region are in a good quantitative and qualitative agreement with experimental data. This demonstrates the efficiency of the hydrodynamic unit for developed software module. But obtained radial coolant temperature profiles differ significantly from the experimental in the vortex flow region. The possible reasons for this discrepancy were analyzed.
Directory of Open Access Journals (Sweden)
Junyi Zou
2017-01-01
Full Text Available To reduce energy consumption or improve energy efficiency, the regenerative devices recently have drawn the public’s eyes. In this paper, a novel hydraulic energy-regenerative shock absorber (HERSA is developed for vehicle suspension to regenerate the vibration energy which is dissipated by conventional viscous dampers into heat waste. At first, the schematic of HERSA is presented and a mathematic model is developed to describe the characteristic of HERSA. Then the parametric sensitivity analysis of the vibration energy is expounded, and the ranking of their influences is k1≫m2>m1>k2≈cs. Besides, a parametric study of HERSA is adopted to research the influences of the key parameters on the characteristic of HERSA. Moreover, an optimization of HERSA is carried out to regenerate more power as far as possible without devitalizing the damping characteristic. To make the optimization results more close to the actual condition, the displacement data of the shock absorber in the road test is selected as the excitation in the optimization. The results show that the RMS of regenerated energy is up to 107.94 W under the actual excitation. Moreover it indicates that the HERSA can improve its performance through the damping control.
Development and validation of the ASTEC-Na thermal-hydraulic models
Energy Technology Data Exchange (ETDEWEB)
Herranz, L. E.; Perez, S.; Bandini, G.; Jacq, F.; Parisi, C.; Berna, C.
2014-07-01
Last years the interest in sodium-cooled fast reactors (SFR) has been fostered worldwide by the search for higher nuclear energy sustainability. This has been reflected in the various international initiatives like GEN-IV International Forum, INPRO or ESNII platforms. At the same time, innovative nuclear reactor designs, particularly SFR, are aiming at even higher safety standards than current LWRs. A proof of it is the consideration of severe accidents since the earliest stages of reactor design. commonalities of LWR and SFR severe accident scenarios suggest that some of the knowledge achieved in the LWR arena might be applicable to some extent to SFRs. This is the spirit underneath of the EU-JASMIN project, which generic goal is developing the ASTEC-Na code from the LWR ASTEC platform. This will entail to t extend and adapt some existing models as well as to implement new ones in all the areas covered, from neutronics and pin thermo-mechanics and pin thermo-mechanics to the in-containment source term behavior by these, going through the indispensable Na thermal-hydraulics. (Author)
Caviedes-Voullième, Daniel; Kesserwani, Georges
2015-12-01
Numerical modelling of wide ranges of different physical scales, which are involved in Shallow Water (SW) problems, has been a key challenge in computational hydraulics. Adaptive meshing techniques have been commonly coupled with numerical methods in an attempt to address this challenge. The combination of MultiWavelets (MW) with the Runge-Kutta Discontinuous Galerkin (RKDG) method offers a new philosophy to readily achieve mesh adaptivity driven by the local variability of the numerical solution, and without requiring more than one threshold value set by the user. However, the practical merits and implications of the MWRKDG, in terms of how far it contributes to address the key challenge above, are yet to be explored. This work systematically explores this, through the verification and validation of the MWRKDG for selected steady and transient benchmark tests, which involves the features of real SW problems. Our findings reveal a practical promise of the SW-MWRKDG solver, in terms of efficient and accurate mesh-adaptivity, but also suggest further improvement in the SW-RKDG reference scheme to better intertwine with, and harness the prowess of, the MW-based adaptivity.
Using hydraulic modeling to address social impacts of small dam removals in southern New Jersey.
Wyrick, Joshua R; Rischman, Brian A; Burke, Christopher A; McGee, Craig; Williams, Chasity
2009-07-01
Small relic mill dams are common in the watersheds of southern New Jersey, dotting the landscape with many small neighborhood lakes. Originally built in the late 1800s, most of these dams have become increasingly unable to handle current design storms due to increased urbanization of the watersheds. Several of these dams have also been classified as "high hazard" by the New Jersey Department of Environmental Protection Dam Safety Division because their failure has the potential for loss of life or extensive property damage. The current private owners are generally unable to afford the high repair costs needed to rehabilitate the dams to current safety standards, and are therefore more inclined to remove them. This research analyses both the physical and social impacts of the removal of two small dams in southern New Jersey, and integrates the two seemingly disparate concepts. Using hydraulic modeling and previous case studies, it is predicted that there will be limited effects to the hydrological and biological characteristics of the stream corridor. A survey distributed to the affected homeowners that live on these lakes shows that the community, however, expects significant impacts to the bio-physical characteristics of the stream corridor, as well financial impacts to their property value and social impacts to their recreational activities. The current study exposes the widening gap between policy makers and landowners, and highlights where complete stakeholder interaction could and should occur.
Ugron, Adám; Szikora, István; Paál, György
2014-06-01
Flow diverters (FDs) have been successfully applied in the recent decade to the treatment of intracranial aneurysms by impairing the communication between the flows in the parent artery and the aneurysm and, thus, the blood within the aneurysm sac. It would be desirable to have a simple and accurate computational method to follow the changes in the peri- and intraaneurysmal flow caused by the presence of FDs. The detailed flow simulation around the intricate wire structure of the FDs has three disadvantages: need for high amount of computational resources and highly skilled professionals to prepare the computational grid, and also the lack of validation that makes the invested effort questionable. In this paper, we propose a porous layer method to model the hydraulic resistance (HR) of one or several layers of the FDs. The basis of this proposal is twofold: first, from an application point of view, the only interesting parameter regarding the function of the FD is its HR; second, we have developed a method to measure the HR with a simple apparatus. We present the results of these measurements and demonstrate their utility in numerical simulations of patient-specific aneurysm simulations.
FORCE FEEDBACK MODEL OF ELECTRO-HYDRAULIC SERVO TELE-OPERATION ROBOT BASED ON VELOCITY CONTROL
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
The tele-operation robotic system which consists of an excavator as the construction robot, and two joysticks for operating the robot from a safe place are useful for performing restoration in damaged areas. In order to accomplish a precise task, the operator needs to feel a realistic sense of task force brought about from a feedback force between the fork glove of slave robot and unfamiliar environment. A novel force feedback model is proposed based on velocity control of cylinder to determine environment force acting" on fork glove. Namely, the feedback force is formed by the error of displacement of joystick with velocity and driving force of piston, and the gain is calculated by the driving force and threshold of driving force of hydraulic cylinder. Moreover, the variable gain improved algorithm is developed to overcome the defect for grasping soft object. Experimental results for fork glove freedom of robotic system are provided to demonstrate the developed algorithm is available for grasping soft object.
Directory of Open Access Journals (Sweden)
Joseph Mtamba
2015-01-01
Full Text Available Vegetation resistance influences water flow in floodplains. Characterization of vegetation for hydraulic modeling includes the description of the spatial variability of vegetation type, height and density. In this research, we explored the use of dual polarized Radarsat-2 wide swath mode backscatter coefficients (σ° and Landsat 5 TM to derive spatial hydraulic roughness. The spatial roughness parameterization included four steps: (i land use classification from Landsat 5 TM; (ii establishing a relationship between σ° statistics and vegetation parameters; (iii relative surface roughness (Ks determination from Synthetic Aperture Radar (SAR backscatter temporal variability; (iv derivation of the spatial distribution of the spatial hydraulic roughness both from Manning’s roughness coefficient look up table (LUT and relative surface roughness. Hydraulic simulations were performed using the FLO-2D hydrodynamic model to evaluate model performance under three different hydraulic modeling simulations results with different Manning’s coefficient parameterizations, which includes SWL1, SWL2 and SWL3. SWL1 is simulated water levels with optimum floodplain roughness (np with channel roughness nc = 0.03 m−1/3/s; SWL2 is simulated water levels with calibrated values for both floodplain roughness np = 0.65 m−1/3/s and channel roughness nc = 0.021 m−1/3/s; and SWL3 is simulated water levels with calibrated channel roughness nc and spatial Manning’s coefficients as derived with aid of relative surface roughness. The model performance was evaluated using Nash-Sutcliffe model efficiency coefficient (E and coefficient of determination (R2, based on water levels measured at a gauging station in the wetland. The overall performance of scenario SWL1 was characterized with E = 0.75 and R2 = 0.95, which was improved in SWL2 to E = 0.95 and R2 = 0.99. When spatially distributed Manning values derived from SAR relative surface values were parameterized in
Development of thermal-hydraulic models for the safety evaluation of CANDU reactors
Energy Technology Data Exchange (ETDEWEB)
Lee, Jae Young; Hwang, Gi Suk; Jung, Yun Sik [Handong Univ., Pohang (Korea, Republic of); No, Hee Cheon; Moon, Young Min [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)
2003-03-15
The objective of the present research is to evaluate the safety analysis for CANDU and to improve the Horizontal Stratification Entrainment Model (HSEM) of RELAP5/MOD3.3. This report includes two items : the one is the development of experimental facility for the safety evaluation of CANDU, the other is the results of comparison with the existing correlations and data. The literature reviews are performed and the database for previous off-take experiments are built. By a survey of state-of-the-articles, the deficiencies of previous works and limitations of existing models are examined. The hydraulic behavior branching through the feeder pipes from the header pipe is analyzed and the test facility of off-take experiment is designed and manufactured as the prototype CANDU6, by a proper scaling methodologies. The test facility contains various branch pipes not only for three directions (top, side and bottom), but for arbitrary directions. The experiments about the onset of entrainment and branch quality only for three directions (top, side and bottom) are carried out by using air-water as working fluids. On the whole, the existing correlations predict the present experimental results well branch quality, entrainment, which validates the availability of experimental facility and methodology. Especially, for the branch quality with top and bottom branches, the different results are shown because of the unstable flow regimes in the horizontal pipe and the different branch diameters. The deficiencies of previous works and limitations of existing models are considered. The off-take experiment for arbitrary branch angles continues as the next year research.
Wong, J. S.; Freer, J.; Bates, P. D.; Sear, D. A.
2012-04-01
Recent research into modelling floodplain inundation processes is primarily concentrated on the simulation of inundation flow without considering the influences of channel morphology and sediment delivery from upstream. River channels are often represented by simplified geometry and implicitly assumed to remain unchanged. However, during and after flood episodes the river bed elevation can change quickly and in some cases drastically. Despite this, the effect of channel geometry and topographic complexity on model results has been largely unexplored. To address this issue, the impact of channel cross-section geometry, and channel long-profile variability on flood inundation extent are examined using a simplified 1D-2D hydraulic model (LISFLOOD-FP) of the Cockermouth floods of November 2009 within an uncertainty analysis framework. The Cockermouth region provides a useful test site for such study because of the availability of channel and floodplain data, the collection of post-event water and wrack marks and the presence of pre-and post-event morphological surveyed data. More importantly, in some areas the river has undergone significant course change and additionally the deposition of stones and debris on the floodplain. The use of relatively simple formulations of critical velocities in the initiation of motion formula enables the construction of a series of hypothetical bedform scenarios among cross-sections. These scenarios can be used as input to LISFLOOD-FP. Slope gradient, Manning roughness coefficients, grain size characteristic, and critical shear stress will be considered in a Monte Carlo simulation framework. The November 2009 Cockermouth flood is simulated and the results are analysed to quantify the accuracy associated with each bedform scenario and to assess how different channel long-profiles affects the performance of LISFLOOD-FP. The study will further analyse and quantify the variability and uncertainty of flood inundation extent resulting from
Global dynamic modeling of electro-hydraulic 3-UPS/S parallel stabilized platform by bond graph
Zhang, Lijie; Guo, Fei; Li, Yongquan; Lu, Wenjuan
2016-08-01
Dynamic modeling of a parallel manipulator(PM) is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the global dynamic model of the PM system becomes increasingly prominent. Currently there lacks further research in global dynamic modeling. A unified modeling approach for the multi-energy domains PM system is proposed based on bond graph and a global dynamic model of the 3-UPS/S parallel stabilized platform involving mechanical and electrical-hydraulic elements is built. Firstly, the screw bond graph theory is improved based on the screw theory, the modular joint model is modeled and the normalized dynamic model of the mechanism is established. Secondly, combined with the electro-hydraulic servo system model built by traditional bond graph, the global dynamic model of the system is obtained, and then the motion, force and power of any element can be obtained directly. Lastly, the experiments and simulations of the driving forces, pressure and flow are performed, and the results show that, the theoretical calculation results of the driving forces are in accord with the experimental ones, and the pressure and flow of the first limb and the third limb are symmetry with each other. The results are reasonable and verify the correctness and effectiveness of the model and the method. The proposed dynamic modeling method provides a reference for modeling of other multi-energy domains system which contains complex PM.
Directory of Open Access Journals (Sweden)
B. Scharnagl
2011-02-01
Full Text Available In situ observations of soil water state variables under natural boundary conditions are often used to estimate field-scale soil hydraulic properties. However, many contributions to the soil hydrological literature have demonstrated that the information content of such data is insufficient to reliably estimate all the soil hydraulic parameters. In this case study, we tested whether prior information about the soil hydraulic properties could help improve the identifiability of the van Genuchten-Mualem (VGM parameters. Three different prior distributions with increasing complexity were formulated using the ROSETTA pedotransfer function (PTF with input data that constitutes basic soil information and is readily available in most vadose zone studies. The inverse problem was posed in a formal Bayesian framework and solved using Markov chain Monte Carlo (MCMC simulation with the DiffeRential Evolution Adaptive Metropolis (DREAM algorithm. Synthetic and real-world soil water content data were used to illustrate our approach. The results of this study corroborate and explicate findings previously reported in the literature. Indeed, soil water content data alone contained insufficient information to reasonably constrain all VGM parameters. The identifiability of these soil hydraulic parameters was substantially improved when an informative prior distribution was used with detailed knowledge of the correlation structure among the respective VGM parameters. A biased prior did not distort the results, which inspires confidence in the robustness and effectiveness of the presented method. The Bayesian framework presented in this study can be applied to a wide range of vadose zone studies and provides a blueprint for the use of prior information in inverse modelling of soil hydraulic properties at various spatial scales.
Energy Technology Data Exchange (ETDEWEB)
Nithianandan, C.K.; Klingenfus, J.A.; Reilly, S.S. [B& W Nuclear Technologies, Lynchburg, VA (United States)
1995-09-01
Droplet breakup at spacer grids and a cladding swelled and ruptured locations plays an important role in the cooling of nuclear fuel rods during the reflooding period of a loss-of-coolant accident (LOCA) in a pressurized water reactor (PWR). During the reflood phase, a spacer grid affects the thermal-hydraulic system behavior through increased turbulence, droplet breakup due to impact on grid straps, grid rewetting, and liquid holdup due to grid form losses. Recently, models to simulate spacer grid effects and blockage and rupture effects on system thermal hydraulics were added to the B&W Nuclear Technologies (BWNT) version of the RELAP5/MOD2 computer code. Several FLECHT-SEASET forced reflood tests, CCTF Tests C1-19 and C2-6, SCTF Test S3-15, and G2 Test 561 were simulated using RELAP5/MOD2-B&W to verify the applicability of the model at the cladding swelled and rupture locations. The results demonstrate the importance of modeling the thermal-hydraulic effects due to grids, and clad swelling and rupture to correctly predict the clad temperature response during the reflood phase of large break LOCA. The RELAP5 models and the test results are described in this paper.
Energy Technology Data Exchange (ETDEWEB)
Chung, Ji Bum [Institute for Advanced Engineering, Yongin (Korea, Republic of); Park, Jong Woon [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
1998-12-31
In order to enhance the dynamic and interactive simulation capability of a system thermal hydraulic code for nuclear power plant, applicability of flow network models in SINDA/FLUINT{sup TM} has been tested by modeling feedwater system and coupling to DSNP which is one of a system thermal hydraulic simulation code for a pressurized heavy water reactor. The feedwater system is selected since it is one of the most important balance of plant systems with a potential to greatly affect the behavior of nuclear steam supply system. The flow network model of this feedwater system consists of condenser, condensate pumps, low and high pressure heaters, deaerator, feedwater pumps, and control valves. This complicated flow network is modeled and coupled to DSNP and it is tested for several normal and abnormal transient conditions such turbine load maneuvering, turbine trip, and loss of class IV power. The results show reasonable behavior of the coupled code and also gives a good dynamic and interactive simulation capabilities for the several mild transient conditions. It has been found that coupling system thermal hydraulic code with a flow network code is a proper way of upgrading simulation capability of DSNP to mature nuclear plant analyzer (NPA). 5 refs., 10 figs. (Author)
Hydraulic manipulator research at ORNL
Energy Technology Data Exchange (ETDEWEB)
Kress, R.L.; Jansen, J.F. [Oak Ridge National Lab., TN (United States); Love, L.J. [Oak Ridge Inst. for Science and Education, TN (United States)
1997-03-01
Recently, task requirements have dictated that manipulator payload capacity increase to accommodate greater payloads, greater manipulator length, and larger environmental interaction forces. General tasks such as waste storage tank cleanup and facility dismantlement and decommissioning require manipulator life capacities in the range of hundreds of pounds rather than tens of pounds. To meet the increased payload capacities demanded by present-day tasks, manipulator designers have turned once again to hydraulics as a means of actuation. In order to successfully design, build, and deploy a new hydraulic manipulator (or subsystem), sophisticated modeling, analysis, and control experiments are usually needed. Oak Ridge National Laboratory (ORNL) has a history of projects that incorporate hydraulics technology, including mobile robots, teleoperated manipulators, and full-scale construction equipment. In addition, to support the development and deployment of new hydraulic manipulators, ORNL has outfitted a significant experimental laboratory and has developed the software capability for research into hydraulic manipulators, hydraulic actuators, hydraulic systems, modeling of hydraulic systems, and hydraulic controls. The purpose of this article is to describe the past hydraulic manipulator developments and current hydraulic manipulator research capabilities at ORNL. Included are example experimental results from ORNL`s flexible/prismatic test stand.
Indian Academy of Sciences (India)
J C Fu; M H Hsu; Y Duann
2016-02-01
Flood is the worst weather-related hazard in Taiwan because of steep terrain and storm. The tropical storm often results in disastrous flash flood. To provide reliable forecast of water stages in rivers is indispensable for proper actions in the emergency response during flood. The river hydraulic model based on dynamic wave theory using an implicit finite-difference method is developed with river roughness updating for flash flood forecast. The artificial neural network (ANN) is employed to update the roughness of rivers in accordance with the observed river stages at each time-step of the flood routing process. Several typhoon events at Tamsui River are utilized to evaluate the accuracy of flood forecasting. The results present the adaptive n-values of roughness for river hydraulic model that can provide a better flow state for subsequent forecasting at significant locations and longitudinal profiles along rivers.
Boltzmann-Electron Model in Aleph.
Energy Technology Data Exchange (ETDEWEB)
Hughes, Thomas Patrick; Hooper, Russell
2014-11-01
We apply the Boltzmann-electron model in the electrostatic, particle-in-cell, finite- element code Aleph to a plasma sheath. By assuming a Boltzmann energy distribution for the electrons, the model eliminates the need to resolve the electron plasma fre- quency, and avoids the numerical "grid instability" that can cause unphysical heating of electrons. This allows much larger timesteps to be used than with kinetic electrons. Ions are treated with the standard PIC algorithm. The Boltzmann-electron model re- quires solution of a nonlinear Poisson equation, for which we use an iterative Newton solver (NOX) from the Trilinos Project. Results for the spatial variation of density and voltage in the plasma sheath agree well with an analytic model
Smith, P D
1982-01-01
BASIC Hydraulics aims to help students both to become proficient in the BASIC programming language by actually using the language in an important field of engineering and to use computing as a means of mastering the subject of hydraulics. The book begins with a summary of the technique of computing in BASIC together with comments and listing of the main commands and statements. Subsequent chapters introduce the fundamental concepts and appropriate governing equations. Topics covered include principles of fluid mechanics; flow in pipes, pipe networks and open channels; hydraulic machinery;
Gvozdik, L.; Polak, M.; Zaruba, J.; Vanecek, M.
2010-12-01
chamber at a constant hydraulic gradient were simulated. As an input data, the values of total porosity measured by several laboratory methods, the results of mercury porosimetry and the statistical evaluation of the size and shape of microfractures measured with electron and optical microscopy were used. For each model solution calibrated on laboratory-measured data the sensitivity analysis of the influence of dimension and character of the microfractures on permeability of rock matrix were carried out. Results will be used in the next phase of the project for model evaluation of transport (advection-dispersion and diffusion) properties of the rock matrix. The presented work is supported by the Ministry of Industry and Trade of Czech Republic under project No. FR-TI1/367.
Energy Technology Data Exchange (ETDEWEB)
Chatzidakis, S., E-mail: schatzid@purdue.edu [Purdue University, School of Nuclear Engineering, West Lafayette, IN 47907 (United States); Hainoun, A. [Atomic Energy Commission of Syria (AECS), Nuclear Engineering Department, P.O. Box 6091, Damascus (Syrian Arab Republic); Doval, A. [Nuclear Engineering Department, Av. Cmdt. Luis Piedrabuena 4950, C.P. 8400, San Carlos de Bariloche, Rio Negro (Argentina); Alhabet, F. [Atomic Energy Commission of Syria (AECS), Nuclear Engineering Department, P.O. Box 6091, Damascus (Syrian Arab Republic); Francioni, F. [Nuclear Engineering Department, Av. Cmdt. Luis Piedrabuena 4950, C.P. 8400, San Carlos de Bariloche, Rio Negro (Argentina); Ikonomopoulos, A. [Institute of Nuclear and Radiological Sciences, Energy, Technology and Safety, National Center for Scientific Research ‘Demokritos’, 15130, Aghia Paraskevi, Athens (Greece); Ridikas, D. [Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna International Centre, A-1400 Vienna (Austria)
2014-03-15
Highlights: • Increased use of thermal-hydraulic codes requires assessment of important phenomena in RRs. • Three independent modeling teams performed analysis of loss of flow transient. • Purpose of this work is to examine the thermal-hydraulic codes response. • To perform benchmark analysis comparing the different codes with experimental measurements. • To identify the impact of the user effect on the computed results, performed with the same codes. - Abstract: This study presents the comparative assessment of three thermal-hydraulic codes employed to model the Indonesian research reactor (RSG-GAS) and simulate the reactor behavior under steady state and loss of flow transient (LOFT). The RELAP5/MOD3, MERSAT and PARET-ANL thermal-hydraulic codes are used by independent research groups to perform benchmark analysis against measurements of coolant and clad temperatures, conducted on an instrumented fuel element inside RSG-GAS core. The results obtained confirm the applicability of RELAP5/MOD3, MERSAT and PARET-ANL on the modeling of loss of flow transient in research reactors. In particular, the three codes are able to simulate flow reversal from downward forced to upward natural convection after pump trip and successful reactor scram. The benchmark results show that the codes predict maximum clad temperature of hot channel conservatively with a maximum overestimation of 27% for RELAP5/MOD3, 17% for MERSAT and 8% for PARET-ANL. As an additional effort, the impact of user effect on the simulation results has been assessed for the code RELAP5/MOD3, where the main differences among the models are presented and discussed.
Bressan, F.; Mantilla, R.
2014-12-01
Sediment movement along the main stem of a watershed is strongly affected by the sediment supply and the channel morphology. Anthropogenic interventions tend to alter the hydraulic conveyance and consequently modify the sediment regime of the main stem. This connection between channel hydraulics and sediment transport is often overlooked in hydrologic models where simplified methods are used for flow and sediment routing. In this study, we adopt a hydrologic-hydraulic modeling approach to quantify the fluvial sediment transport along the main stem of a watershed during a storm event. The hydrologic model CUENCAS is implemented to estimate the sub-hourly hydrographs of the major tributaries of the watershed. The simulated hydrographs are used as boundary conditions for the depth-averaged two-dimensional hydraulic model FESMWS to simulate the propagation of the flood wave along the main stem. The corresponding sub-hourly, unsteady non-equilibrium sediment transport along the main stem is also simulated with FESWMS. This procedure is applied to a highly managed agricultural watershed of Iowa. The study site has a catchment area of 70 Km2 with soils that are silty clay loams. The land-use is mostly row crop, but in the past decade a large portion of the watershed was converted to native prairie. The main stem is a meandering stream with a length of 15 Km and ten major tributaries contribute to its flow. Several sections of the main stem have been heavily channelized and straightened since the 1930s. Different grain size distributions and sediment boundary conditions are investigated to discern the effects of land-use changes and channelization on the sediment regime along the main stem. The simulations are able to capture the typical hysteresis between flow and sediment transport. The results indicate that the in-stream sediment transport rate is in general higher in the channelized sections and depends, to a certain extent, on the degree of straightening.
A Graph Theoretic Approach for Hydraulic Fracturing and Wellbore Leakage Risk Modeling
Glosser, D.; Rose, K.; Bauer, J. R.; Warner, T.
2016-12-01
Recent large scale development of unconventional formations for fossil energy has raised concerns over the potential for fluid leakage between subsurface systems and wellbores. This is particularly true in regions with extensive drilling history, where spatial densities of wellbores are higher, and where significant uncertainties in the location and mechanical integrity of such wellbores exist. The generation of induced fracture networks during hydraulic fracturing may increase subsurface connectivity, and create the potential for unwanted fluid migration between operational and legacy wellbores and subsurface fracture networks. We present a graph theoretic approach for identifying geospatial regions and wellbores at increased risk for subsurface connectivity based on wellbore proximity and local geologic characteristics. The algorithm transforms user inputted geospatial data (geologic and wellbore x,y,z) to graph structure, where wellbores are represented as nodes, and where potential overlapping fracture network zones are represented as edges. The algorithm can be used to complement existing fracture models to better account for the reach of induced fractures, and to identify spatial extents at increased risk for unwanted subsurface connectivity. Additionally, the model can be used to identify regions in need of geophysical detection methods for locating undocumented wells. As a result, the method can be part of a cumulative strategy to reduce uncertainty inherent to combined geologic and engineered systems. The algorithm has been successfully tested against a known leakage scenario in Pennsylvania. In addition to identifying wells associated with the leakage event, the algorithm identified two other higher risk networks in the region. The algorithm output provides valuable information for industry to develop environmentally safe drilling and injection plans; and for regulators to identify specific wellbores at greater risk for leakage, and to develop targeted
Mathews, Alyssa
Emissions from the combustion of fossil fuels are a growing pollution concern throughout the global community, as they have been linked to numerous health issues. The freight transportation sector is a large source of these emissions and is expected to continue growing as globalization persists. Within the US, the expanding development of the natural gas industry is helping to support many industries and leading to increased transportation. The process of High Volume Hydraulic Fracturing (HVHF) is one of the newer advanced extraction techniques that is increasing natural gas and oil reserves dramatically within the US, however the technique is very resource intensive. HVHF requires large volumes of water and sand per well, which is primarily transported by trucks in rural areas. Trucks are also used to transport waste away from HVHF well sites. This study focused on the emissions generated from the transportation of HVHF materials to remote well sites, dispersion, and subsequent health impacts. The Geospatial Intermodal Freight Transport (GIFT) model was used in this analysis within ArcGIS to identify roadways with high volume traffic and emissions. High traffic road segments were used as emissions sources to determine the atmospheric dispersion of particulate matter using AERMOD, an EPA model that calculates geographic dispersion and concentrations of pollutants. Output from AERMOD was overlaid with census data to determine which communities may be impacted by increased emissions from HVHF transport. The anticipated number of mortalities within the impacted communities was calculated, and mortality rates from these additional emissions were computed to be 1 in 10 million people for a simulated truck fleet meeting stricter 2007 emission standards, representing a best case scenario. Mortality rates due to increased truck emissions from average, in-use vehicles, which represent a mixed age truck fleet, are expected to be higher (1 death per 341,000 people annually).
Mallants, Dirk; Simunek, Jirka; Gerke, Kirill
2015-04-01
Coal Seam Gas production generates large volumes of "produced" water that may contain compounds originating from the use of hydraulic fracturing fluids. Such produced water also contains elevated concentrations of naturally occurring inorganic and organic compounds, and usually has a high salinity. Leaching of produced water from storage ponds may occur as a result of flooding or containment failure. Some produced water is used for irrigation of specific crops tolerant to elevated salt levels. These chemicals may potentially contaminate soil, shallow groundwater, and groundwater, as well as receiving surface waters. This paper presents an application of scenario modelling using the reactive transport model for variably-saturated media HP1 (coupled HYDRUS-1D and PHREEQC). We evaluate the fate of hydraulic fracturing chemicals and naturally occurring chemicals in soil as a result of unintentional release from storage ponds or when produced water from Coal Seam Gas operations is used in irrigation practices. We present a review of exposure pathways and relevant hydro-bio-geo-chemical processes, a collation of physico-chemical properties of organic/inorganic contaminants as input to a set of generic simulations of transport and attenuation in variably saturated soil profiles. We demonstrate the ability to model the coupled processes of flow and transport in soil of contaminants associated with hydraulic fracturing fluids and naturally occurring contaminants.
Rotational nuclear models and electron scattering
Energy Technology Data Exchange (ETDEWEB)
Moya de Guerra, E.
1986-05-01
A review is made of the basic formalism involved in the application of nuclear rotational models to the problem of electron scattering from axially symmetric deformed nuclei. Emphasis is made on the use of electron scattering to extract information on the nature of the collective rotational model. In this respect, the interest of using polarized beam and target is discussed with the help of illustrative examples. Concerning the nuclear structure four rotational models are considered: Two microscopic models, namely the Projected Hartree-Fock (PHF) and cranking models; and two collective models, the rigid rotor and the irrotational flow models. The problem of current conservation within the different models is also discussed.
Vrettas, M. D.; Fung, I. Y.
2015-12-01
High-frequency multi-year observations of the water table at several wells in the Angelo Coast Range Reserve in the Eel River Watershed in northern California show rapid fluctuations, where the water table, some 10-15 meters below the surface, rises by as much as 1 meter in a day or two after the first storms of the rain season. The observations highlight preferential flow through weathered bedrock, which can store as much as 30% of the moisture in the column ("rock moisture"). This rapid transfer of moisture and storage at depth could have a significant impact on ecosystem dynamics and the water and energy budgets of the atmosphere on various time scales. Despite its high importance, preferential flow through weather bedrock is not routinely captured in most climate models. This work presents a new hydraulic conductivity parameterization that captures the preferential flow, with straightforward implementation into current global climate models. The hydraulic conductivity is represented as a product of the effective saturation (normalized water content) and a background hydraulic conductivity Kbkg, drawn from a depth dependent lognormal distribution. A unique feature of the parameterization is that the variance of hydraulic conductivity is large when there is little rock moisture, and decreases with increasing saturation, mimicking flow through fractures. The new method is applied to seven wells locations on a steep (35 degrees) hill-slope in the Eel River watershed in Northern California, for the duration of six years and estimates of the model parameters are provided by assimilating, into Richards' equation, measurements of precipitation [mm] and water table depths [m] at 30-minute time intervals. The simulation results show that the new approach yields a good agreement of the rapid rise of the observed water table at the tested well locations. Furthermore, the water stored in the weathered bedrock is estimated to be in the range between 32% and 41%, which could
Carles Brangarí, Albert; Sanchez-Vila, Xavier; Freixa, Anna; M. Romaní, Anna; Rubol, Simonetta; FernÃ ndez-Garcia, Daniel
2017-01-01
The accumulation of biofilms in porous media is likely to influence the overall hydraulic properties and, consequently, a sound understanding of the process is required for the proper design and management of many technological applications. In order to bring some light into this phenomenon we present a mechanistic model to study the variably saturated hydraulic properties of bio-amended soils. Special emphasis is laid on the distribution of phases at pore-scale and the mechanisms to retain and let water flow through, providing valuable insights into phenomena behind bioclogging. Our approach consists in modeling the porous media as an ensemble of capillary tubes, obtained from the biofilm-free water retention curve. This methodology is extended by the incorporation of a biofilm composed of bacterial cells and extracellular polymeric substances (EPS). Moreover, such a microbial consortium displays a channeled geometry that shrinks/swells with suction. Analytical equations for the volumetric water content and the relative permeability can then be derived by assuming that biomass reshapes the pore space following specific geometrical patterns. The model is discussed by using data from laboratory studies and other approaches already existing in the literature. It can reproduce (i) displacements of the retention curve toward higher saturations and (ii) permeability reductions of distinct orders of magnitude. Our findings also illustrate how even very small amounts of biofilm may lead to significant changes in the hydraulic properties. We, therefore, state the importance of accounting for the hydraulic characteristics of biofilms and for a complex/more realistic geometry of colonies at the pore-scale.
Energy Technology Data Exchange (ETDEWEB)
Fanselau, R.W.; Thakkar, J.G.; Hiestand, J.W.; Cassell, D.
1981-03-01
The Comparative Thermal-Hydraulic Evaluation of Steam Generators program represents an analytical investigation of the thermal-hydraulic characteristics of four PWR steam generators. The analytical tool utilized in this investigation is the CALIPSOS code, a three-dimensional flow distribution code. This report presents the steady state thermal-hydraulic characteristics on the secondary side of a Westinghouse Model 51 steam generator. Details of the CALIPSOS model with accompanying assumptions, operating parameters, and transport correlations are identified. Comprehensive graphical and numerical results are presented to facilitate the desired comparison with other steam generators analyzed by the same flow distribution code.
Johnson, S.; Chiaramonte, L.; Cruz, L.; Izadi, G.
2016-12-01
Advances in the accuracy and fidelity of numerical methods have significantly improved our understanding of coupled processes in unconventional reservoirs. However, such multi-physics models are typically characterized by many parameters and require exceptional computational resources to evaluate systems of practical importance, making these models difficult to use for field analyses or uncertainty quantification. One approach to remove these limitations is through targeted complexity reduction and field data constrained parameterization. For the latter, a variety of field data streams may be available to engineers and asset teams, including micro-seismicity from proximate sites, well logs, and 3D surveys, which can constrain possible states of the reservoir as well as the distributions of parameters. We describe one such workflow, using the Argos multi-physics code and requisite geomechanical analysis to parameterize the underlying models. We illustrate with a field study involving a constraint analysis of various field data and details of the numerical optimizations and model reduction to demonstrate how complex models can be applied to operation design in hydraulic fracturing operations, including selection of controllable completion and fluid injection design properties. The implication of this work is that numerical methods are mature and computationally tractable enough to enable complex engineering analysis and deterministic field estimates and to advance research into stochastic analyses for uncertainty quantification and value of information applications.
Department of Homeland Security — This table is required whenever hydraulic structures are shown in the flood profile. It is also required if levees are shown on the FIRM, channels containing the...
Liedl, Rudolf; Ptak, Thomas
2003-11-01
A new reactive transport modelling approach and examples of its application are presented, dealing with the impact of sorption/desorption kinetics on the spreading of solutes, e.g. organic contaminants, in groundwater. Slow sorption/desorption is known from the literature to be strongly responsible for the retardation of organic contaminants. The modelling concept applied in this paper quantifies sorption/desorption kinetics by an intra-particle diffusion approach. According to this idea, solute uptake by or release from the aquifer material is modelled at small scale by a "slow" diffusion process where the diffusion coefficient is reduced as compared to the aqueous diffusion coefficient due to (i) the size and shape of intra-particle pores and (ii) retarded transport of solutes within intra-particle pores governed by a nonlinear sorption isotherm. This process-based concept has the advantage of requiring only measurable model parameters, thus avoiding fitting parameters like first-order rate coefficients. In addition, the approach presented here allows for modelling of slow sorption/desorption in lithologically nonuniform media. Therefore, it accounts for well-known experimental findings indicating that sorptive properties depend on (i) the grain size distribution of the aquifer material and (ii) the lithological composition (e.g. percentage of quartz, sandstone, limestone, etc.) of each grain size fraction. The small-scale physico-chemical model describing sorption/desorption is coupled to a large-scale model of groundwater flow and solute transport. Consequently, hydraulic heterogeneities may also be considered by the overall model. This coupling is regarded as an essential prerequisite for simulating field-scale scenarios which will be addressed by a forthcoming publication. This paper focuses on mathematical model formulation, implementation of the numerical code and lab-scale model applications highlighting the sorption and desorption behavior of an organic
Matgen, P.; Montanari, M.; Hostache, R.; Pfister, L.; Hoffmann, L.; Plaza, D.; Pauwels, V. R. N.; de Lannoy, G. J. M.; de Keyser, R.; Savenije, H. H. G.
2010-09-01
With the onset of new satellite radar constellations (e.g. Sentinel-1) and advances in computational science (e.g. grid computing) enabling the supply and processing of multi-mission satellite data at a temporal frequency that is compatible with real-time flood forecasting requirements, this study presents a new concept for the sequential assimilation of Synthetic Aperture Radar (SAR)-derived water stages into coupled hydrologic-hydraulic models. The proposed methodology consists of adjusting storages and fluxes simulated by a coupled hydrologic-hydraulic model using a Particle Filter-based data assimilation scheme. Synthetic observations of water levels, representing satellite measurements, are assimilated into the coupled model in order to investigate the performance of the proposed assimilation scheme as a function of both accuracy and frequency of water level observations. The use of the Particle Filter provides flexibility regarding the form of the probability densities of both model simulations and remote sensing observations. We illustrate the potential of the proposed methodology using a twin experiment over a widely studied river reach located in the Grand-Duchy of Luxembourg. The study demonstrates that the Particle Filter algorithm leads to significant uncertainty reduction of water level and discharge at the time step of assimilation. However, updating the storages of the model only improves the model forecast over a very short time horizon. A more effective way of updating thus consists in adjusting both states and inputs. The proposed methodology, which consists in updating the biased forcing of the hydraulic model using information on model errors that is inferred from satellite observations, enables persistent model improvement. The present schedule of satellite radar missions is such that it is likely that there will be continuity for SAR-based operational water management services. This research contributes to evolve reactive flood management into
U.S. Geological Survey, Department of the Interior — This digital geospatial data set contains the locations, values, and uncertainties of hydraulic-head observations used in the calibration of the transient model of...
U.S. Geological Survey, Department of the Interior — This digital data set defines the hydraulic-head values in 16 model layers used to initiate the transient simulation of the Death Valley regional ground-water flow...
U.S. Geological Survey, Department of the Interior — This digital geospatial data set contains the locations, values, and uncertainties of hydraulic-head observations used in the calibration of the transient model of...
Jhorar, R.K.
2002-01-01
Key words: evapotranspiration, effective soil hydraulic parameters, remote sensing, regional water management, groundwater use, Bhakra Irrigation System, India.The meaningful application of water management simulation models at regional scale for the analysis of alternate water manage
DEFF Research Database (Denmark)
Conrad, Finn
2006-01-01
The paper presents and discusses a R&D-view on trends in development and best practise in modelling, simulation and design of both low-pressure and high-pressure tap water hydraulic components and systems for motion control as well as open-ended solutions various industrial applications. The focus...... is on the advantages using ordinary tap water and the range of application areas are illustrated with examples, in particular within the food processing industry, humidification operations, water mist systems for fire fighting, high water pressure cleaners, water moisturising systems for wood processing, lumber drying...... is that the components operate with pure water from the tap without additives of any kind. Hence water hydraulics takes the benefit of pure water as fluid being environmentally friendly, easy to clean sanitary design, non-toxic, non-flammable, inexpensive, readily available and easily disposable. The low-pressure tap...
Hayek, Mohamed
2016-04-01
This work develops a simple exact and explicit solution of the one-dimensional transient and nonlinear Richards' equation for soils in a special case of exponential water retention curve and power law hydraulic conductivity. The exact solution is obtained as traveling wave based on the approach proposed by Philip (1957, 1967) and adopted by Zlotnik et al. (2007). The obtained solution is novel, and it expresses explicitly the water content as function of the depth and time. It can be useful to model infiltration into semi-infinite soils with time-dependent boundary conditions and infiltration with constant boundary condition but space-dependent initial condition. A complete analytical inverse procedure based on the proposed analytical solution is presented which allows the estimation of hydraulic parameters. The proposed exact solution is also important for the verification of numerical schemes as well as for checking the implementation of time-dependent boundary conditions.
Institute of Scientific and Technical Information of China (English)
WONG Pak-kin; TAM Lap-mou; LI Ke
2007-01-01
In modern four-stroke engine technology, variable valve timing and lift control offers potential benefits for making a high-performance engine. A novel electro-hydraulic fully variable valve train for four-stroke automotive engines is introduced. The construction of the nonlinear mathematic model of the valve train system and its dynamic analysis are also presented. Experimental and simulation results show that the novel electro-hydraulic valve train can achieve fully variable valve timing and lift control. Consequently the engine performance on different loads and speeds will be significantly increased. The technology also permits the elimination of the traditional throttle valve in the gasoline engines and increases engine design flexibility.
Energy Technology Data Exchange (ETDEWEB)
SPILIOTOPOULOS AA; SWANSON LC; SHANNON R; TONKIN MJ
2011-04-07
Robust performance evaluation represents one of the most challenging aspects of groundwater pump-and-treat (P&T) remedy implementation. In most cases, the primary goal of the P&T system is hydraulic containment, and ultimately recovery, of contaminants to protect downgradient receptors. Estimating the extent of hydraulic containment is particularly challenging under changing flow patterns due to variable pumping, boundaries and/or other conditions. We present a systematic approach to estimate hydraulic containment using multiple lines of evidence based on (a) water-level mapping and (b) groundwater modeling. Capture Frequency Maps (CFMs) are developed by particle tracking on water-level maps developed for each available water level data set using universal kriging. In a similar manner, Capture Efficiency Maps (CEMs) are developed by particle tracking on water-levels calculated using a transient groundwater flow model: tracking is undertaken independently for each stress period using a very low effective porosity, depicting the 'instantaneous' fate of each particle each stress period. Although conceptually similar, the two methods differ in their underlying assumptions and their limitations: their use together identifies areas where containment may be reliable (i.e., where the methods are in agreement) and where containment is uncertain (typically, where the methods disagree). A field-scale example is presented to illustrate these concepts.
Development of modelling tools for thermo-hydraulic analyses and design of JT-60SA TF coils
Energy Technology Data Exchange (ETDEWEB)
Lacroix, Benoit, E-mail: benoit.lacroix@cea.fr [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Portafaix, Christophe [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Barabaschi, Pietro [Fusion For Energy, D-85748 Garching (Germany); Duchateau, Jean-Luc; Hertout, Patrick; Lamaison, Valerie; Nicollet, Sylvie; Reynaud, Pascal [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Villari, Rosaria [Euratom-ENEA Association, IT-00044 Frascati (Italy); Zani, Louis [Fusion For Energy, D-85748 Garching (Germany)
2011-10-15
In the framework of the JT-60SA project, the Toroidal Field (TF) coils design has required to address reliably the choice between multiple design options and to calculate the temperature margin criterion for the superconductor. For this purpose, a tool was developed in two stages, interfacing the ANSYS code, used to model the thermal diffusion between the casing and the winding pack, with the GANDALF code which solves the 1D thermo-hydraulics inside each conductor. The first version of this Thermo-hydraulic EXtended TOol (TEXTO) was developed for producing conservative results and has allowed to simulate the fast discharge of the magnet, providing valuable results such as the mass flow expelled from each pancake. In the second stage, the ANSYS code was configured for modelling the helium transport in the casing and in the winding pack, thus computing more realistic transverse heat fluxes to be injected into the GANDALF code for an accurate calculation of the temperature margin. This second version of TEXTO, which integrates the TACOS (Thermo-hydraulic Ansys COmputation Semi 3D) module, has been used for studying the feasibility of positioning the helium inlets in the electrical connections. The temperature margin has then been found close but below the criterion of 1 K.
Directory of Open Access Journals (Sweden)
Ingrid Tomac
2017-02-01
Full Text Available This paper presents an improved understanding of coupled hydro-thermo-mechanical (HTM hydraulic fracturing of quasi-brittle rock using the bonded particle model (BPM within the discrete element method (DEM. BPM has been recently extended by the authors to account for coupled convective–conductive heat flow and transport, and to enable full hydro-thermal fluid–solid coupled modeling. The application of the work is on enhanced geothermal systems (EGSs, and hydraulic fracturing of hot dry rock (HDR is studied in terms of the impact of temperature difference between rock and a flowing fracturing fluid. Micro-mechanical investigation of temperature and fracturing fluid effects on hydraulic fracturing damage in rocks is presented. It was found that fracture is shorter with pronounced secondary microcracking along the main fracture for the case when the convective–conductive thermal heat exchange is considered. First, the convection heat exchange during low-viscosity fluid infiltration in permeable rock around the wellbore causes significant rock cooling, where a finger-like fluid infiltration was observed. Second, fluid infiltration inhibits pressure rise during pumping and delays fracture initiation and propagation. Additionally, thermal damage occurs in the whole area around the wellbore due to rock cooling and cold fluid infiltration. The size of a damaged area around the wellbore increases with decreasing fluid dynamic viscosity. Fluid and rock compressibility ratio was found to have significant effect on the fracture propagation velocity.
Directory of Open Access Journals (Sweden)
N.P. Serdun
2015-12-01
Full Text Available The paper presents an experimental study into the thermal-hydraulic performance of the VK-300 reactor based on a model of a single draft tube at a pressure of 3.4MPa, various flow rates and the model inlet relative enthalpies of –0.05 to 0.2. The experimental procedures include generation of a steam-water mixture circulation with a preset flow rate and a relative enthalpy through the test section at a pressure of 3.3 to 3.4MPa, and measurement of thermal-hydraulic parameters within the circuit's representative upflow and downflow lengths of practical interest. There have been confirmed the designs used to support the reactor facility serviceability and the assumptions concerning the thermal-hydraulic performance of a natural circulation circuit used in the analysis thereof. It has been shown that, across the analyzed range of the relative enthalpy values, the draft tube has an annular-dispersed or an annular flow of the steam-water mixture, both providing for the significant separation of the steam-water mixture (Ksep=0.4 at the draft tube edges and in the mixing chamber. The perforation in the upper part of the draft tubes allows the separation coefficient to be increased at the first stage and creates more favorable conditions for the second-stage separation. The measured values of the void fraction in the mixing chamber and in the draft tube are in a satisfactory agreement with calculations based on Z.L. Miropolskiy's method and the RELAP code and may be used to verify the VK-300 thermal-hydraulic codes. It has been shown that steam may enter the ring slit that simulates the annular space and reach the reactor core inlet. Further investigations need to be conducted to study this effect for its guaranteed exclusion and for the development of emergency response procedures.
Smith, L. A.; Barbour, S. L.; Hendry, M. J.; Novakowski, K.; van der Kamp, G.
2016-07-01
Characterizing the hydraulic conductivity (K) of aquitards is difficult due to technical and logistical difficulties associated with field-based methods as well as the cost and challenge of collecting representative and competent core samples for laboratory analysis. The objective of this study was to produce a multiscale comparison of vertical and horizontal hydraulic conductivity (Kv and Kh, respectively) of a regionally extensive Cretaceous clay-rich aquitard in southern Saskatchewan. Ten vibrating wire pressure transducers were lowered into place at depths between 25 and 325 m, then the annular was space was filled with a cement-bentonite grout. The in situ Kh was estimated at the location of each transducer by simulating the early-time pore pressure measurements following setting of the grout using a 2-D axisymmetric, finite element, numerical model. Core samples were collected during drilling for conventional laboratory testing for Kv to compare with the transducer-determined in situ Kh. Results highlight the importance of scale and consideration of the presence of possible secondary features (e.g., fractures) in the aquitard. The proximity of the transducers to an active potash mine (˜1 km) where depressurization of an underlying aquifer resulted in drawdown through the aquitard provided a unique opportunity to model the current hydraulic head profile using both the Kh and Kv estimates. Results indicate that the transducer-determined Kh estimates would allow for the development of the current hydraulic head distribution, and that simulating the pore pressure recovery can be used to estimate moderately low in situ Kh (<10-11 m s-1).
Directory of Open Access Journals (Sweden)
G. Baroni
2010-02-01
Full Text Available Data of soil hydraulic properties forms often a limiting factor in unsaturated zone modelling, especially at the larger scales. Investigations for the hydraulic characterization of soils are time-consuming and costly, and the accuracy of the results obtained by the different methodologies is still debated. However, we may wonder how the uncertainty in soil hydraulic parameters relates to the uncertainty of the selected modelling approach. We performed an intensive monitoring study during the cropping season of a 10 ha maize field in Northern Italy. The data were used to: i compare different methods for determining soil hydraulic parameters and ii evaluate the effect of the uncertainty in these parameters on different variables (i.e. evapotranspiration, average water content in the root zone, flux at the bottom boundary of the root zone simulated by two hydrological models of different complexity: SWAP, a widely used model of soil moisture dynamics in unsaturated soils based on Richards equation, and ALHyMUS, a conceptual model of the same dynamics based on a reservoir cascade scheme. We employed five direct and indirect methods to determine soil hydraulic parameters for each horizon of the experimental profile. Two methods were based on a parameter optimization of: a laboratory measured retention and hydraulic conductivity data and b field measured retention and hydraulic conductivity data. The remaining three methods were based on the application of widely used Pedo-Transfer Functions: c Rawls and Brakensiek, d HYPRES, and e ROSETTA. Simulations were performed using meteorological, irrigation and crop data measured at the experimental site during the period June – October 2006. Results showed a wide range of soil hydraulic parameter values generated with the different methods, especially for the saturated hydraulic conductivity K_{sat} and the shape parameter α of the van Genuchten curve. This is reflected in a variability of
Directory of Open Access Journals (Sweden)
G. Baroni
2009-06-01
Full Text Available Data of soil hydraulic properties forms often a limiting factor in unsaturated zone modelling, especially at the larger scales. Investigations for the hydraulic characterization of soils are time-consuming and costly, and the accuracy of the results obtained by the different methodologies is still debated. However, we may wonder how the uncertainty in soil hydraulic parameters relates to the uncertainty of the selected modelling approach.
We performed an intensive monitoring study during the cropping season of a 10 ha maize field in Northern Italy. These data were used to: i compare different methods for determining soil hydraulic parameters and ii evaluate the effect of the uncertainty in these parameters on different outputs (i.e. evapotranspiration, water content in the root zone, fluxes through the bottom boundary of the root zone of two hydrological models with different complexity: SWAP, a widely used model of soil moisture dynamics in unsaturated soils based on Richards equation, and ALHyMUS, a conceptual model of the same dynamics based on a reservoir cascade scheme. We employed five direct and indirect methods to determine soil hydraulic parameters for each horizon of the experimental field. Two methods were based on a parameter optimization of: a laboratory measured retention and hydraulic conductivity data and b field measured retention and hydraulic conductivity data. Three methods were based on the application of widely used Pedo-Transfer Functions: c Rawls and Brakensiek; d HYPRES; and e ROSETTA. Simulations were performed using meteorological, irrigation and crop data measured at the experimental site during the period June–October 2006.
Results showed a wide range of soil hydraulic parameter values evaluated with the different methods, especially for the saturated hydraulic conductivity K_{sat} and the shape parameter α of the Van Genuchten curve. This is reflected in a variability of the
Hydraulic pressing of oilseeds: Experimental determination and modeling of yield and pressing rates
Willems, P.; Kuipers, N.J.M.; de Haan, A.B.
2008-01-01
The influence of pressure, temperature and moisture content on the oil yield and rate of conventional hydraulic expression of sesame and linseed is discussed as well as the influence of pressure and temperature for rapeseed, palm kernel, jatropha and dehulled jatropha. Yield increased with increase
Hydraulic pressing of oilseeds: Experimental determination and modeling of yield and pressing rates
Willems, P.; Kuipers, N.J.M.; Haan, de A.B.
2008-01-01
The influence of pressure, temperature and moisture content on the oil yield and rate of conventional hydraulic expression of sesame and linseed is discussed as well as the influence of pressure and temperature for rapeseed, palm kernel, jatropha and dehulled jatropha. Yield increased with increase
Blokker, E.J.M.
2010-01-01
In the water distribution network water quality process take place influenced by de flow velocity and residence time of the water in the network. In order to understand how the water quality changes in the water distribution network, a good understanding of hydraulics is required. Specifically in
Serpooshan, Vahid
Among various natural biopolymers, type I collagen gels have demonstrated the highest potential as biomimetic scaffolds for tissue engineering (TE). However, the successful application of collagen gels requires a greater understanding of the relationship between their microstructure and physical-mechanical properties. Therefore, a precise method to modulate collagen gel microstructure in order to attain optimal scaffold properties for diverse biomedical applications is necessary. This dissertation describes a new approach to produce collagen gels with defined microstructures, quantified by hydraulic permeability ( k), in order to optimize scaffold properties for TE applications. It was hypothesized that the measurement of k can be used to study the role of microstructure in collagen gel properties, as well as cell function and cell-scaffold interactions. Applying increasing levels of plastic compression (PC) to the highly hydrated collagen gels resulted in an increase in collagen fibrillar density, reduced Happel model derived k values, increased gel stiffness, promoted MSC metabolic activity, osteogenic differentiation, and mineral deposition, while cell-induced gel contraction diminished. Thus, collagen gels with lower k and higher stiffness values exhibited greater potential for bone tissue engineering. Correlating between collagen gel microstructure, k, and fibroblast function within collagen gels indicated that increasing the level of PC yielded a reduction in pore size and an increase in fibril bundle diameter. Decrease in k values resulted in a decrease in gel contraction and an increase in cell metabolic activity. An increase in cell density accelerated contraction. Therefore, fibroblast function within collagen gels can be optimised by a balance between the microstructure, k, and cell seeding density. Developing a micromechanical model to measure experimental k of collagen gels during confined compression revealed the formation of a dense collagen lamella
Nanoscale zero-valent iron for metal/metalloid removal from model hydraulic fracturing wastewater.
Sun, Yuqing; Lei, Cheng; Khan, Eakalak; Chen, Season S; Tsang, Daniel C W; Ok, Yong Sik; Lin, Daohui; Feng, Yujie; Li, Xiang-Dong
2017-06-01
Nanoscale zero-valent iron (nZVI) was tested for the removal of Cu(II), Zn(II), Cr(VI), and As(V) in model saline wastewaters from hydraulic fracturing. Increasing ionic strength (I) from 0.35 to 4.10 M (Day-1 to Day-90 wastewaters) increased Cu(II) removal (25.4-80.0%), inhibited Zn(II) removal (58.7-42.9%), slightly increased and then reduced Cr(VI) removal (65.7-44.1%), and almost unaffected As(V) removal (66.7-75.1%) by 8-h reaction with nZVI at 1-2 g L(-1). The removal kinetics conformed to pseudo-second-order model, and increasing I decreased the surface area-normalized rate coefficient (ksa) of Cu(II) and Cr(VI), probably because agglomeration of nZVI in saline wastewaters restricted diffusion of metal(loid)s to active surface sites. Increasing I induced severe Fe dissolution from 0.37 to 0.77% in DIW to 4.87-13.0% in Day-90 wastewater; and Fe dissolution showed a significant positive correlation with Cu(II) removal. With surface stabilization by alginate and polyvinyl alcohol, the performance of entrapped nZVI in Day-90 wastewater was improved for Zn(II) and Cr(VI), and Fe dissolution was restrained (3.20-7.36%). The X-ray spectroscopic analysis and chemical speciation modelling demonstrated that the difference in removal trends from Day-1 to Day-90 wastewaters was attributed to: (i) distinctive removal mechanisms of Cu(II) and Cr(VI) (adsorption, (co-)precipitation, and reduction), compared to Zn(II) (adsorption) and As(V) (bidentate inner-sphere complexation); and (ii) changes in solution speciation (e.g., from Zn(2+) to ZnCl3(-) and ZnCl4(2-); from CrO4(2-) to CaCrO4 complex). Bare nZVI was susceptible to variations in wastewater chemistry while entrapped nZVI was more stable and environmentally benign, which could be used to remove metals/metalloids before subsequent treatment for reuse/disposal. Copyright © 2017 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
O. Laganier
2013-09-01
Full Text Available Mediterranean catchments are regularly affected by fast and flash floods. Numerous hydrologic models were developed, and allow to reconstruct these floods. However, these approaches often concern average size basins, of some hundreds km2. At more important scales (>1000 km2, a coupling of hydrologic and hydraulic models appears to be an adapted solution. This study analyses the performances of a coupling of models and compares them with those of others modelling strategies. The distributed SCS-LR hydrologic model implemented in the ATHYS modelling platform ( http://www.athys-soft.org , and the MASCARET hydraulic modelling code, based on full Saint-Venant equations, are employed. The coupling is applied to the Gardon river basin (2040 km2, in the southeast of France. The results are satisfactory at the downstream stations. Furthermore, the coupling has few parameters, expecting interesting perspectives for flood forecasting.
Electronic Education System Model-2
Güllü, Fatih; Kuusik, Rein; Laanpere, Mart
2015-01-01
In this study we presented new EES Model-2 extended from EES model for more productive implementation in e-learning process design and modelling in higher education. The most updates were related to uppermost instructional layer. We updated learning processes object of the layer for adaptation of educational process for young and old people,…
Neumann, R. B.; Cardon, Z. G.; Rockwell, F. E.; Teshera-Levye, J.; Zwieniecki, M.; Holbrook, N. M.
2013-12-01
The movement of water from moist to dry soil layers through the root systems of plants, referred to as hydraulic redistribution (HR), occurs throughout the world and is thought to influence carbon and water budgets and ecosystem functioning. The realized hydrologic, biogeochemical, and ecological consequences of HR depend on the amount of redistributed water, while the ability to assess these impacts requires models that correctly capture HR magnitude and timing. Using several soil types and two eco-types of Helianthus annuus L. in split-pot experiments, we examined how well the widely used HR modeling formulation developed by Ryel et al. (2002) could match experimental determination of HR across a range of water potential driving gradients. H. annuus carries out extensive nighttime transpiration, and though over the last decade it has become more widely recognized that nighttime transpiration occurs in multiple species and many ecosystems, the original Ryel et al. (2002) formulation does not include the effect of nighttime transpiration on HR. We developed and added a representation of nighttime transpiration into the formulation, and only then was the model able to capture the dynamics and magnitude of HR we observed as soils dried and nighttime stomatal behavior changed, both influencing HR.
Mackay, D. S.; Ewers, B. E.; Roberts, D. E.; McDowell, N. G.; Pendall, E.; Frank, J. M.; Reed, D. E.; Massman, W. J.; Mitra, B.
2011-12-01
Changing climate drivers including temperature, humidity, precipitation, and carbon dioxide (CO2) concentrations directly control land surface exchanges of CO2 and water. In a profound way these responses are modulated by disturbances that are driven by or exacerbated by climate change. Predicting these changes is challenging given that the feedbacks between environmental controls, disturbances, and fluxes are complex. Flux data in areas of bark beetle outbreaks in the western U.S.A. show differential declines in carbon and water flux in response to the occlusion of xylem by associated fungi. For example, bark beetle infestation at the GLEES AmeriFlux site manifested in a decline in summer water use efficiency to 60% in the year after peak infestation compared to previous years, and no recovery of carbon uptake following a period of high vapor pressure deficit. This points to complex feedbacks between disturbance and differential ecosystem reaction and relaxation responses. Theory based on plant hydraulics and extending to include links to carbon storage and exhaustion has potential for explaining these dynamics with simple, yet rigorous models. In this spirit we developed a coupled model that combines an existing model of canopy water and carbon flow, TREES [e.g., Loranty et al., 2010], with the Sperry et al., [1998] plant hydraulic model. The new model simultaneously solves carbon uptake and losses along with plant hydraulics, and allows for testing specific hypotheses on feedbacks between xylem dysfunction, stomatal and non-stomatal controls on photosynthesis and carbon allocation, and autotrophic and heterotrophic respiration. These are constrained through gas exchange, root vulnerability to cavitation, sap flux, and eddy covariance data in a novel model complexity-testing framework. Our analysis focuses on an ecosystem gradient spanning sagebrush to subalpine forests. Our modeling results support hypotheses on feedbacks between hydraulic dysfunction and 1) non
Mirfenderesgi, Golnazalsadat; Bohrer, Gil; Matheny, Ashley M.; Fatichi, Simone; Moraes Frasson, Renato Prata; Schäfer, Karina V. R.
2016-07-01
The finite difference ecosystem-scale tree crown hydrodynamics model version 2 (FETCH2) is a tree-scale hydrodynamic model of transpiration. The FETCH2 model employs a finite difference numerical methodology and a simplified single-beam conduit system to explicitly resolve xylem water potentials throughout the vertical extent of a tree. Empirical equations relate water potential within the stem to stomatal conductance of the leaves at each height throughout the crown. While highly simplified, this approach brings additional realism to the simulation of transpiration by linking stomatal responses to stem water potential rather than directly to soil moisture, as is currently the case in the majority of land surface models. FETCH2 accounts for plant hydraulic traits, such as the degree of anisohydric/isohydric response of stomata, maximal xylem conductivity, vertical distribution of leaf area, and maximal and minimal xylem water content. We used FETCH2 along with sap flow and eddy covariance data sets collected from a mixed plot of two genera (oak/pine) in Silas Little Experimental Forest, NJ, USA, to conduct an analysis of the intergeneric variation of hydraulic strategies and their effects on diurnal and seasonal transpiration dynamics. We define these strategies through the parameters that describe the genus level transpiration and xylem conductivity responses to changes in stem water potential. Our evaluation revealed that FETCH2 considerably improved the simulation of ecosystem transpiration and latent heat flux in comparison to more conventional models. A virtual experiment showed that the model was able to capture the effect of hydraulic strategies such as isohydric/anisohydric behavior on stomatal conductance under different soil-water availability conditions.
Electronic noise modeling in statistical iterative reconstruction.
Xu, Jingyan; Tsui, Benjamin M W
2009-06-01
We consider electronic noise modeling in tomographic image reconstruction when the measured signal is the sum of a Gaussian distributed electronic noise component and another random variable whose log-likelihood function satisfies a certain linearity condition. Examples of such likelihood functions include the Poisson distribution and an exponential dispersion (ED) model that can approximate the signal statistics in integration mode X-ray detectors. We formulate the image reconstruction problem as a maximum-likelihood estimation problem. Using an expectation-maximization approach, we demonstrate that a reconstruction algorithm can be obtained following a simple substitution rule from the one previously derived without electronic noise considerations. To illustrate the applicability of the substitution rule, we present examples of a fully iterative reconstruction algorithm and a sinogram smoothing algorithm both in transmission CT reconstruction when the measured signal contains additive electronic noise. Our simulation studies show the potential usefulness of accurate electronic noise modeling in low-dose CT applications.
Jatnieks, J.; Popovs, K.; Klints, I.; Timuhins, A.; Kalvans, A.; Delina, A.; Saks, T.
2012-04-01
The cover of Quaternary sediments especially in formerly glaciated territories usually is the most complex part of the sedimentary sequences. In regional hydro-geological models it is often assumed as a single layer with uniform or calibrated properties (Valner 2003). However, the properties and structure of Quaternary sediments control the groundwater recharge: it can either direct the groundwater flow horizontally towards discharge in topographic lows or vertically, recharging groundwater in the bedrock. This work aims to present calibration results and detail our experience while integrating a scalable generalization of hydraulic conductivity for Quaternary strata in the regional groundwater modelling system for the Baltic artesian basin - MOSYS V1. We also present a method for solving boundary transitions between spatial clusters of lithologically similar structure. In this study the main unit of generalization is the spatial cluster. Clusters are obtained from distance calculations combining the Normalized Compression Distance (NCD) metric, calculated by the CompLearn parameter-free machine learning toolkit, with normalized Euclidean distance measures for coordinates of the borehole log data. A hierarchical clustering solution is used for obtaining cluster membership identifier for each borehole. Using boreholes as generator points for Voronoi tessellation and dissolving resulting polygons according to their cluster membership attribute, allows us to obtain spatial regions representing a certain degree of similarity in lithological structure. This degree of similarity and the spatial heterogeneity of the cluster polygons can be varied by different flattening of the hierarchical cluster model into variable number of clusters. This provides a scalable generalization solution which can be adapted according to model calibration performance. Using the dissimilarity matrix of the NCD metric, a borehole most similar to all the others from the lithological structure
Courbet, C.; DICK, P.; Lefevre, M.; Wittebroodt, C.; Matray, J.; Barnichon, J.
2013-12-01
In the framework of its research on the deep disposal of radioactive waste in shale formations, the French Institute for Radiological Protection and Nuclear Safety (IRSN) has developed a large array of in situ programs concerning the confining properties of shales in their underground research laboratory at Tournemire (SW France). One of its aims is to evaluate the occurrence and processes controlling radionuclide migration through the host rock, from the disposal system to the biosphere. Past research programs carried out at Tournemire covered mechanical, hydro-mechanical and physico-chemical properties of the Tournemire shale as well as water chemistry and long-term behaviour of the host rock. Studies show that fluid circulations in the undisturbed matrix are very slow (hydraulic conductivity of 10-14 to 10-15 m.s-1). However, recent work related to the occurrence of small scale fractures and clay-rich fault gouges indicate that fluid circulations may have been significantly modified in the vicinity of such features. To assess the transport properties associated with such faults, IRSN designed a series of in situ and laboratory experiments to evaluate the contribution of both diffusive and advective process on water and solute flux through a clay-rich fault zone (fault core and damaged zone) and in an undisturbed shale formation. As part of these studies, Modular Mini-Packer System (MMPS) hydraulic testing was conducted in multiple boreholes to characterize hydraulic conductivities within the formation. Pressure data collected during the hydraulic tests were analyzed using the nSIGHTS (n-dimensional Statistical Inverse Graphical Hydraulic Test Simulator) code to estimate hydraulic conductivity and formation pressures of the tested intervals. Preliminary results indicate hydraulic conductivities of 5.10-12 m.s-1 in the fault core and damaged zone and 10-14 m.s-1 in the adjacent undisturbed shale. Furthermore, when compared with neutron porosity data from borehole
Status of Galileo interim radiation electron model
Garrett, H. B.; Jun, I.; Ratliff, J. M.; Evans, R. W.; Clough, G. A.; McEntire, R. W.
2003-01-01
Measurements of the high energy, omni-directional electron environment by the Galileo spacecraft Energetic Particle Detector (EDP) were used to develop a new model of Jupiter's trapped electron radiation in the jovian equatorial plane for the range 8 to 16 Jupiter radii.
Hydraulic rams; a comparative investigation
Tacke, J.H.P.M.
1988-01-01
A mathematical model describing the essential features of hydraulic ram operation is developed in order to clarify the possibilities and limitations of the ram relative to its site and its adjustments. The model distinguishes three different periods in the pumping cycle of the hydraulic ram: acceler
Energy Technology Data Exchange (ETDEWEB)
Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States); Gromov, R. [Argonne National Lab. (ANL), Argonne, IL (United States); Makarashvili, Vakhtang [Argonne National Lab. (ANL), Argonne, IL (United States); Heltemes, Thad [Argonne National Lab. (ANL), Argonne, IL (United States); Sun, Zaijing [Argonne National Lab. (ANL), Argonne, IL (United States); Wardle, Kent E. [Argonne National Lab. (ANL), Argonne, IL (United States); Bailey, James [Argonne National Lab. (ANL), Argonne, IL (United States); Stepinski, Dominique [Argonne National Lab. (ANL), Argonne, IL (United States); Jerden, James [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)
2015-01-30
In support of the development of accelerator-driven production of fission product Mo-99 as proposed by SHINE Medical Technologies, a 35 MeV electron linac was used to irradiate depleted-uranium (DU) uranyl sulfate dissolved in pH 1 sulfuric acid at average power densities of 6 kW, 12 kW, and 15 kW. During these irradiations, gas bubbles were generated in the solution due to the radiolytic decomposition of water molecules in the solution. Multiple video cameras were used to record the behavior of bubble generation and transport in the solution. Seven six-channel thermocouples were used to record temperature gradients in the solution from self-heating. Measurements of hydrogen and oxygen concentrations in a helium sweep gas were recorded by a gas chromatograph to estimate production rates during irradiation. These data are being used to validate a computational fluid dynamics (CFD) model of the experiment that includes multiphase flow and a custom bubble injection model for the solution region.
DEFF Research Database (Denmark)
Conrad, Finn; Pobedza, J.; Sobczyk, A.
2003-01-01
proportional valves and servo actuators for motion control and power transmission undertaken in co-operation by Technical University, DTU and Cracow University of Technology, CUT. The results of this research co-operation include engineering design and test of simulation models compared with two mechatronic......The paper presents experimental-based modelling, simulation, analysis and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. The contributions includes results from on-going research projects on fluid power and mechatronics based on tap water hydraulic...... test rig facilities powered by environmental friendly water hydraulic servo actuator system. Test rigs with measurement and data acquisition system were designed and build up with tap water hydraulic components of the Danfoss Nessie® product family. This paper presents selected experimental...
Modeling microwave/electron-cloud interaction
Mattes, M; Zimmermann, F
2013-01-01
Starting from the separate codes BI-RME and ECLOUD or PyECLOUD, we are developing a novel joint simulation tool, which models the combined effect of a charged particle beam and of microwaves on an electron cloud. Possible applications include the degradation of microwave transmission in tele-communication satellites by electron clouds; the microwave-transmission tecchniques being used in particle accelerators for the purpose of electroncloud diagnostics; the microwave emission by the electron cloud itself in the presence of a magnetic field; and the possible suppression of electron-cloud formation in an accelerator by injecting microwaves of suitable amplitude and frequency. A few early simulation results are presented.
Energy Technology Data Exchange (ETDEWEB)
Rakowski, Cynthia L.; Serkowski, John A.; Richmond, Marshall C.; Perkins, William A.
2010-12-01
Although fisheries biology studies are frequently performed at US Army Corps of Engineers (USACE) projects along the Columbia and Snake Rivers, there is currently no consistent definition of the ``forebay'' and ``tailrace'' regions for these studies. At this time, each study may use somewhat arbitrary lines (e.g., the Boat Restriction Zone) to define the upstream and downstream limits of the study, which may be significantly different at each project. Fisheries researchers are interested in establishing a consistent definition of project forebay and tailrace regions for the hydroelectric projects on the lower Columbia and Snake rivers. The Hydraulic Extent of a project was defined by USACE (Brad Eppard, USACE-CENWP) as follows: The river reach directly upstream (forebay) and downstream (tailrace) of a project that is influenced by the normal range of dam operations. Outside this reach, for a particular river discharge, changes in dam operations cannot be detected by hydraulic measurement. The purpose of this study was to, in consultation with USACE and regional representatives, develop and apply a consistent set of criteria for determining the hydraulic extent of each of the projects in the lower Columbia and Snake rivers. A 2D depth-averaged river model, MASS2, was applied to the Snake and Columbia Rivers. New computational meshes were developed most reaches and the underlying bathymetric data updated to the most current survey data. The computational meshes resolved each spillway bay and turbine unit at each project and extended from project to project. MASS2 was run for a range of total river flows and each flow for a range of project operations at each project. The modeled flow was analyzed to determine the range of velocity magnitude differences and the range of flow direction differences at each location in the computational mesh for each total river flow. Maps of the differences in flow direction and velocity magnitude were created. USACE
Le Bourgeois, O.; Bouvier, C.; Brunet, P.; Ayral, P.-A.
2016-10-01
Modeling soil water flow requires the knowledge of numerous parameters associated to the water content and the soil hydraulic properties. Direct estimations of those parameters in laboratory require expensive equipment and the obtained parameters are generally not representative at the field scale because of the limitation of core sample size. Indirect methods such as inverse modeling are known to get efficient estimations and are easier to set up and process for large-scale studies. In this study, we investigated the capacity of an inverse modeling procedure to estimate the soil and the bedrock hydrodynamic properties only from in situ soil water content measurements at multiple depths under natural conditions. Multi-objective parameter optimization was performed using the HYDRUS-1D software and an external optimization procedure based on the NSGA-II algorithm. In a midslope shallow soil, water content was monitored at 3 depths, 20, 40, and 60 cm during 12 intense rainfall events, whose amounts ranged between 50 and 250 mm and duration between 1 and 5 days. The vertical profile was considered as 2 layers of soils above a third layer representing the weathered schist rock. This deep layer acted as a deep boundary condition, which features the bedrock permeability and water storage. Each layer was described trough the 6 parameters of the Mualem-van Genuchten formulation. The calibrated parameters appeared to have very low uncertainty while allowing a good modelisation of the observed water content variations. The calibrated saturated water content was close to the laboratory porosity measurements while the saturated hydraulic conductivity showed that the soil was highly permeable, as measured in the field. The inverse modeling approach allowed an estimation of the hydraulic properties of the bedrock layer where no measurement was available. The bedrock layer was found to have a low saturated hydraulic conductivity (model failed sometimes to reproduce the saturation
Energy Technology Data Exchange (ETDEWEB)
Saghafi, Mahdi [Department of Energy Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); Ghofrani, Mohammad Bagher, E-mail: ghofrani@sharif.edu [Department of Energy Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); D’Auria, Francesco [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, San Piero a Grado, Pisa (Italy)
2016-07-15
Highlights: • A thermal-hydraulic nodalization for PSB-VVER test facility has been developed. • Station blackout accident is modeled with the developed nodalization in MELCOR code. • The developed nodalization is qualified at both steady state and transient levels. • MELCOR predictions are qualitatively and quantitatively in acceptable range. • Fast Fourier Transform Base Method is used to quantify accuracy of code predictions. - Abstract: This paper deals with the development of a qualified thermal-hydraulic nodalization for modeling Station Black-Out (SBO) accident in PSB-VVER Integral Test Facility (ITF). This study has been performed in the framework of a research project, aiming to develop an appropriate accident management support tool for Bushehr nuclear power plant. In this regard, a nodalization has been developed for thermal-hydraulic modeling of the PSB-VVER ITF by MELCOR integrated code. The nodalization is qualitatively and quantitatively qualified at both steady-state and transient levels. The accuracy of the MELCOR predictions is quantified in the transient level using the Fast Fourier Transform Base Method (FFTBM). FFTBM provides an integral representation for quantification of the code accuracy in the frequency domain. It was observed that MELCOR predictions are qualitatively and quantitatively in the acceptable range. In addition, the influence of different nodalizations on MELCOR predictions was evaluated and quantified using FFTBM by developing 8 sensitivity cases with different numbers of control volumes and heat structures in the core region and steam generator U-tubes. The most appropriate case, which provided results with minimum deviations from the experimental data, was then considered as the qualified nodalization for analysis of SBO accident in the PSB-VVER ITF. This qualified nodalization can be used for modeling of VVER-1000 nuclear power plants when performing SBO accident analysis by MELCOR code.
Wei, Zhongbao; Zhao, Jiyun; Skyllas-Kazacos, Maria; Xiong, Binyu
2014-08-01
The present study focuses on dynamic thermal-hydraulic modeling for the all-vanadium flow battery and investigations on the impact of stack flow patterns on battery performance. The inhomogeneity of flow rate distribution and reversible entropic heat are included in the thermal-hydraulic model. The electrolyte temperature in tanks is modeled with the finite element modeling (FEM) technique considering the possible non-uniform distribution of electrolyte temperature. Results show that the established model predicts electrolyte temperature accurately under various ambient temperatures and current densities. Significant temperature gradients exist in the battery system at extremely low flow rates, while the electrolyte temperature tends to be the same in different components under relatively high flow rates. Three stack flow patterns including flow without distribution channels and two cases of flow with distribution channels are compared to investigate their effects on battery performance. It is found that the flow rates are not uniformly distributed in cells especially when the stack is not well designed, while adding distribution channels alleviates the inhomogeneous phenomenon. By comparing the three flow patterns, it is found that the serpentine-parallel pattern is preferable and effectively controls the uniformity of flow rates, pressure drop and electrolyte temperature all at expected levels.
Neutronic and thermal-hydraulic coupling for 3D reactor core modeling combining MCB and fluent
Directory of Open Access Journals (Sweden)
Królikowski Igor P.
2015-09-01
Full Text Available Three-dimensional simulations of neutronics and thermal hydraulics of nuclear reactors are a tool used to design nuclear reactors. The coupling of MCB and FLUENT is presented, MCB allows to simulate neutronics, whereas FLUENT is computational fluid dynamics (CFD code. The main purpose of the coupling is to exchange data such as temperature and power profile between both codes. Temperature required as an input parameter for neutronics is significant since cross sections of nuclear reactions depend on temperature. Temperature may be calculated in thermal hydraulics, but this analysis needs as an input the power profile, which is a result from neutronic simulations. Exchange of data between both analyses is required to solve this problem. The coupling is a better solution compared to the assumption of estimated values of the temperatures or the power profiles; therefore the coupled analysis was created. This analysis includes single transient neutronic simulation and several steady-state thermal simulations. The power profile is generated in defined points in time during the neutronic simulation for the thermal analysis to calculate temperature. The coupled simulation gives information about thermal behavior of the reactor, nuclear reactions in the core, and the fuel evolution in time. Results show that there is strong influence of neutronics on thermal hydraulics. This impact is stronger than the impact of thermal hydraulics on neutronics. Influence of the coupling on temperature and neutron multiplication factor is presented. The analysis has been performed for the ELECTRA reactor, which is lead-cooled fast reactor concept, where the coolant fl ow is generated only by natural convection
Multidisciplinary Modelling Tools for Power Electronic Circuits
DEFF Research Database (Denmark)
Bahman, Amir Sajjad
This thesis presents multidisciplinary modelling techniques in a Design For Reliability (DFR) approach for power electronic circuits. With increasing penetration of renewable energy systems, the demand for reliable power conversion systems is becoming critical. Since a large part of electricity...... in reliability assessment of power modules, a three-dimensional lumped thermal network is proposed to be used for fast, accurate and detailed temperature estimation of power module in dynamic operation and different boundary conditions. Since an important issue in the reliability of power electronics...... are generic and valid to be used in circuit simulators or any programing software. These models are important building blocks for the reliable design process or performance assessment of power electronic circuits. The models can save time and cost in power electronics packaging and power converter to evaluate...
McGuire, Daniel
A numerical tool for the simulation of the thermal dynamics of pipe networks with heat transfer has been developed with the novel capability of modeling supercritical fluids. The tool was developed to support the design and deployment of two thermal-hydraulic loops at Carleton University for the purpose of heat transfer studies in supercritical and near-critical fluids. First, the system was characterized based on its defining features; the characteristic length of the flow path is orders of magnitude larger than the other characteristic lengths that define the system's geometry; the behaviour of the working fluid in the supercritical thermodynamic state. An analysis of the transient thermal behaviour of the model's domains is then performed to determine the accuracy and range of validity of the modeling approach for simulating the transient thermal behaviour of a thermal-hydraulic loop. Preliminary designs of three test section geometries, for the purpose of heat transfer studies, are presented in support of the overall design of the Carleton supercritical thermal-hydraulic loops. A 7-rod-bundle, annular and tubular geometries are developed with support from the new numerical tool. Materials capable of meeting the experimental requirements while operating in supercritical water are determined. The necessary geometries to satisfy the experimental goals are then developed based on the material characteristics and predicted heat transfer behaviour from previous simulation results. An initial safety analysis is performed on the test section designs, where they are evaluated against the ASME Boiler, Pressure Vessel, and Pressure Piping Code standard, required for safe operation and certification.
Directory of Open Access Journals (Sweden)
Ireneusz Laks
2017-04-01
Full Text Available The paper presents a method for the correction of low quality DEMs, based on aerial photographs, for use in 2D flood modeling. The proposed method was developed and tested on the example of the floodplain of the Warta River, which is the third biggest river in Poland. The correction of DEM is based on a series of a small number of measurements using GPS-RTK, which enable calculations of the global statistics like mean error (ME, root mean square error (RMSE and standard deviation (SD. The impact of DEM accuracy was estimated by using a 2D numerical model. The calculated values of flow velocities, inundation area and volume of floodplain for each tested DEM were compared. The analyses indicate that, after the correction procedure, the predictions of corrected DEM based on poor quality data is in good quantitative and qualitative agreement with the referenced LIDAR DEM. The proposed method may be applied in the areas for which high resolution DEMs based on LIDAR data are not available.
Zhang, Jie; Tejada-Martínez, Andrés E; Zhang, Qiong; Lei, Hongxia
2014-04-01
The capability of predicting hydraulic and disinfection efficiencies of ozone disinfection contactors is essential for evaluating existing contactors and improving future designs. Previous attempts based on ideal and non-ideal models for the hydraulics and simplified mechanisms for chemical reaction modeling have resulted in low accuracy and are restricted to contactors with simple geometries. This manuscript develops a modeling framework for the ozonation process by combining computational fluid dynamics (CFD) with a kinetics-based reaction modeling for the first time. This computational framework has been applied to the full-scale ozone contactor operated by the City of Tampa Water Department. Flow fields, residence time distribution, ozone concentration distribution, and concentration-contact time (CT) distribution within the contactor have been predicted via the computational framework. The predictions of ozone and bromate concentrations at sample points agree well with physical experimental data measured in the contactor. The predicted CT values at the contactor outlet demonstrate that the disinfection performance of the ozone contactor operated by the City of Tampa Water Department is sufficient to meet regulation requirements. The impact of seasonal flow rate change on disinfection performance is found to be significant and deserves attention during the management and operation of a water treatment plant.
Directory of Open Access Journals (Sweden)
Soroosh Mahmoodi
2016-01-01
Full Text Available An interesting model which was able to recuperate and reuse braking energy was investigated. It was named series hybrid hydraulic/electric system (SHHES. The innovated model was presented for heavy hybrid vehicles to overcome the existing drawbacks of single energy storage sources. The novelty of this paper was investigation of a new series hybrid vehicle with triple sources, combustion engine, electric motor, and hydraulic sources. It was simulated with MATLAB-Simulink and different operational mode of control system was investigated. The aim was to improve the efficiency of the energy-loading components in the power train system and the transmission system independently. The ability to store and reuse the kinetic energy was added to the system to prevent energy wasting while the vehicle was braking. Control models were also investigated to realize suitable control algorithms to offer the best efficiency in system components for different vehicle conditions. The torque control strategy based on fuzzy logic controller was proposed to achieve better vehicle performance while the fuel consumption was minimized. The results implied efficient storage and usage in the transmission system. A small vehicle model experimentally verified the simulation results.
Directory of Open Access Journals (Sweden)
J. A. P. Pollacco
2017-06-01
Full Text Available Descriptions of soil hydraulic properties, such as the soil moisture retention curve, θ(h, and saturated hydraulic conductivities, Ks, are a prerequisite for hydrological models. Since the measurement of Ks is expensive, it is frequently derived from statistical pedotransfer functions (PTFs. Because it is usually more difficult to describe Ks than θ(h from pedotransfer functions, Pollacco et al. (2013 developed a physical unimodal model to compute Ks solely from hydraulic parameters derived from the Kosugi θ(h. This unimodal Ks model, which is based on a unimodal Kosugi soil pore-size distribution, was developed by combining the approach of Hagen–Poiseuille with Darcy's law and by introducing three tortuosity parameters. We report here on (1 the suitability of the Pollacco unimodal Ks model to predict Ks for a range of New Zealand soils from the New Zealand soil database (S-map and (2 further adaptations to this model to adapt it to dual-porosity structured soils by computing the soil water flux through a continuous function of an improved bimodal pore-size distribution. The improved bimodal Ks model was tested with a New Zealand data set derived from historical measurements of Ks and θ(h for a range of soils derived from sandstone and siltstone. The Ks data were collected using a small core size of 10 cm diameter, causing large uncertainty in replicate measurements. Predictions of Ks were further improved by distinguishing topsoils from subsoil. Nevertheless, as expected, stratifying the data with soil texture only slightly improved the predictions of the physical Ks models because the Ks model is based on pore-size distribution and the calibrated parameters were obtained within the physically feasible range. The improvements made to the unimodal Ks model by using the new bimodal Ks model are modest when compared to the unimodal model, which is explained by the poor accuracy of measured total porosity. Nevertheless, the new bimodal
Pollacco, Joseph Alexander Paul; Webb, Trevor; McNeill, Stephen; Hu, Wei; Carrick, Sam; Hewitt, Allan; Lilburne, Linda
2017-06-01
Descriptions of soil hydraulic properties, such as the soil moisture retention curve, θ(h), and saturated hydraulic conductivities, Ks, are a prerequisite for hydrological models. Since the measurement of Ks is expensive, it is frequently derived from statistical pedotransfer functions (PTFs). Because it is usually more difficult to describe Ks than θ(h) from pedotransfer functions, Pollacco et al. (2013) developed a physical unimodal model to compute Ks solely from hydraulic parameters derived from the Kosugi θ(h). This unimodal Ks model, which is based on a unimodal Kosugi soil pore-size distribution, was developed by combining the approach of Hagen-Poiseuille with Darcy's law and by introducing three tortuosity parameters. We report here on (1) the suitability of the Pollacco unimodal Ks model to predict Ks for a range of New Zealand soils from the New Zealand soil database (S-map) and (2) further adaptations to this model to adapt it to dual-porosity structured soils by computing the soil water flux through a continuous function of an improved bimodal pore-size distribution. The improved bimodal Ks model was tested with a New Zealand data set derived from historical measurements of Ks and θ(h) for a range of soils derived from sandstone and siltstone. The Ks data were collected using a small core size of 10 cm diameter, causing large uncertainty in replicate measurements. Predictions of Ks were further improved by distinguishing topsoils from subsoil. Nevertheless, as expected, stratifying the data with soil texture only slightly improved the predictions of the physical Ks models because the Ks model is based on pore-size distribution and the calibrated parameters were obtained within the physically feasible range. The improvements made to the unimodal Ks model by using the new bimodal Ks model are modest when compared to the unimodal model, which is explained by the poor accuracy of measured total porosity. Nevertheless, the new bimodal model provides an
Shalaginova, Z. I.
2016-03-01
The mathematical model and calculation method of the thermal-hydraulic modes of heat points, based on the theory of hydraulic circuits, being developed at the Melentiev Energy Systems Institute are presented. The redundant circuit of the heat point was developed, in which all possible connecting circuits (CC) of the heat engineering equipment and the places of possible installation of control valve were inserted. It allows simulating the operating modes both at central heat points (CHP) and individual heat points (IHP). The configuration of the desired circuit is carried out automatically by removing the unnecessary links. The following circuits connecting the heating systems (HS) are considered: the dependent circuit (direct and through mixing elevator) and independent one (through the heater). The following connecting circuits of the load of hot water supply (HWS) were considered: open CC (direct water pumping from pipelines of heat networks) and a closed CC with connecting the HWS heaters on single-level (serial and parallel) and two-level (sequential and combined) circuits. The following connecting circuits of the ventilation systems (VS) were also considered: dependent circuit and independent one through a common heat exchanger with HS load. In the heat points, water temperature regulators for the hot water supply and ventilation and flow regulators for the heating system, as well as to the inlet as a whole, are possible. According to the accepted decomposition, the model of the heat point is an integral part of the overall heat-hydraulic model of the heat-supplying system having intermediate control stages (CHP and IHP), which allows to consider the operating modes of the heat networks of different levels connected with each other through CHP as well as connected through IHP of consumers with various connecting circuits of local systems of heat consumption: heating, ventilation and hot water supply. The model is implemented in the Angara data
Jackisch, Conrad; Demand, Dominic; Allroggen, Niklas; Loritz, Ralf; Zehe, Erwin
2017-04-01
In order to discuss hypothesis testing in hydrology, the question of the solid foundation of such tests has to be answered. But how certain are we about our measurements of the components of the water balance and the states and dynamics of the complex systems? What implicit assumptions or bias are already embedded in our perception of the processes? How can we find light in the darkness of heterogeneity? We will contribute examples from experimental findings, modelling approaches and landscape analysis to the discussion. Example soil moisture and the soil continuum: The definition of soil moisture as fraction of water in the porous medium assumes locally well-mixed conditions. Moreover, a unique relation of soil water retention presumes instant local thermodynamic equilibrium in the pore water arrangement. We will show findings from soil moisture responses to precipitation events, from irrigation experiments, and from a model study of initial infiltration velocities. The results highlight, that the implicit assumption relating soil moisture state dynamics with actual soil water flow is biased towards the slow end of the actual velocity distribution and rather blind for preferential flow acting in a very small proportion of the pore space. Moreover, we highlight the assumption of a well-defined continuum during the extrapolation of point-scale measurements and why spatially and temporally continuous observation techniques of soil water states are essential for advancing our understanding and development of subsurface process theories. Example hydraulic conductivity: Hydraulic conductivity lies at the heart of hydrological research and modelling. Its values can range across several orders of magnitude at a single site alone. Yet, we often consider it a crisp, effective parameter. We have conducted measurements of soil hydraulic conductivity in the lab and in the field. Moreover, we assessed infiltration capacity and conducted plot-scale irrigation experiments to
Chen, Huili; Liang, Zhongyao; Liu, Yong; Liang, Qiuhua; Xie, Shuguang
2017-10-01
The projected frequent occurrences of extreme flood events will cause significant losses to crops and will threaten food security. To reduce the potential risk and provide support for agricultural flood management, prevention, and mitigation, it is important to account for flood damage to crop production and to understand the relationship between flood characteristics and crop losses. A quantitative and effective evaluation tool is therefore essential to explore what and how flood characteristics will affect the associated crop loss, based on accurately understanding the spatiotemporal dynamics of flood evolution and crop growth. Current evaluation methods are generally integrally or qualitatively based on statistic data or ex-post survey with less diagnosis into the process and dynamics of historical flood events. Therefore, a quantitative and spatial evaluation framework is presented in this study that integrates remote sensing imagery and hydraulic model simulation to facilitate the identification of historical flood characteristics that influence crop losses. Remote sensing imagery can capture the spatial variation of crop yields and yield losses from floods on a grid scale over large areas; however, it is incapable of providing spatial information regarding flood progress. Two-dimensional hydraulic model can simulate the dynamics of surface runoff and accomplish spatial and temporal quantification of flood characteristics on a grid scale over watersheds, i.e., flow velocity and flood duration. The methodological framework developed herein includes the following: (a) Vegetation indices for the critical period of crop growth from mid-high temporal and spatial remote sensing imagery in association with agricultural statistics data were used to develop empirical models to monitor the crop yield and evaluate yield losses from flood; (b) The two-dimensional hydraulic model coupled with the SCS-CN hydrologic model was employed to simulate the flood evolution process
Valdes-Abellan, Javier; Jiménez-Martínez, Joaquín; Candela, Lucila; Jacques, Diederik; Kohfahl, Claus; Tamoh, Karim
2017-06-01
The use of non-conventional water (e.g., treated wastewater, desalinated water) for different purposes is increasing in many water scarce regions of the world. Its use for irrigation may have potential drawbacks, because of mineral dissolution/precipitation processes, such as changes in soil physical and hydraulic properties (e.g., porosity, permeability), modifying infiltration and aquifer recharge processes or blocking root growth. Prediction of soil and groundwater impacts is essential for achieving sustainable agricultural practices. A numerical model to solve unsaturated water flow and non-isothermal multicomponent reactive transport has been modified implementing the spatio-temporal evolution of soil physical and hydraulic properties. A long-term process simulation (30 years) of agricultural irrigation with desalinated water, based on a calibrated/validated 1D numerical model in a semi-arid region, is presented. Different scenarios conditioning reactive transport (i.e., rainwater irrigation, lack of gypsum in the soil profile, and lower partial pressure of CO2 (pCO2)) have also been considered. Results show that although boundary conditions and mineral soil composition highly influence the reactive processes, dissolution/precipitation of carbonate species is triggered mainly by pCO2, closely related to plant roots. Calcite dissolution occurs in the root zone, precipitation takes place under it and at the soil surface, which will lead a root growth blockage and a direct soil evaporation decrease, respectively. For the studied soil, a gypsum dissolution up to 40 cm depth is expected at long-term, with a general increase of porosity and hydraulic conductivity.
Meller, Michael; Chipka, Jordan; Volkov, Alexander; Bryant, Matthew; Garcia, Ephrahim
2016-11-03
Hydraulic control systems have become increasingly popular as the means of actuation for human-scale legged robots and assistive devices. One of the biggest limitations to these systems is their run time untethered from a power source. One way to increase endurance is by improving actuation efficiency. We investigate reducing servovalve throttling losses by using a selective recruitment artificial muscle bundle comprised of three motor units. Each motor unit is made up of a pair of hydraulic McKibben muscles connected to one servovalve. The pressure and recruitment state of the artificial muscle bundle can be adjusted to match the load in an efficient manner, much like the firing rate and total number of recruited motor units is adjusted in skeletal muscle. A volume-based effective initial braid angle is used in the model of each recruitment level. This semi-empirical model is utilized to predict the efficiency gains of the proposed variable recruitment actuation scheme versus a throttling-only approach. A real-time orderly recruitment controller with pressure-based thresholds is developed. This controller is used to experimentally validate the model-predicted efficiency gains of recruitment on a robot arm. The results show that utilizing variable recruitment allows for much higher efficiencies over a broader operating envelope.
Hydraulic Stability of Accropode Armour
DEFF Research Database (Denmark)
Jensen, T.; Burcharth, H. F.; Frigaard, Peter
, and to assess the influence of core permeability on the hydraulic stability of Accropodes. Two structures were examined, one with a relatively permeable core and one with a relatively impermeable core. In November/December 1995, Ph.D.-student Marten Christensen carried out the model tests on the structure...... with permeable core (crushed granite with a gradation of 5-8 mm). The outcome of this study is described in "Hydraulic Stability of Single-Layer Dolos and Accropode Armour Layers" by Christensen & Burcharth (1995). In January/February 1996, Research Assistant Thomas Jensen carried out a similar study......The present report describes the hydraulic model tests of Accropode armour layers carried out at the Hydraulics Laboratory at Aalborg University from November 1995 through March 1996. The objective of the model tests was to investigate the hydraulic stability of Accropode armour layers...
Hydraulic Stability of Accropode Armour
DEFF Research Database (Denmark)
Jensen, T.; Burcharth, H. F.; Frigaard, Peter
, and to assess the influence of core permeability on the hydraulic stability of Accropodes. Two structures were examined, one with a relatively permeable core and one with a relatively impermeable core. In November/December 1995, Ph.D.-student Marten Christensen carried out the model tests on the structure...... with permeable core (crushed granite with a gradation of 5-8 mm). The outcome of this study is described in "Hydraulic Stability of Single-Layer Dolos and Accropode Armour Layers" by Christensen & Burcharth (1995). In January/February 1996, Research Assistant Thomas Jensen carried out a similar study......The present report describes the hydraulic model tests of Accropode armour layers carried out at the Hydraulics Laboratory at Aalborg University from November 1995 through March 1996. The objective of the model tests was to investigate the hydraulic stability of Accropode armour layers...
Energy Technology Data Exchange (ETDEWEB)
Vallejos, G.; Ponce Caballero, C.; Quintal Franco, C.; Mendez Novelo, R.
2009-07-01
The main objective of this study was to assess the portions of plug flow and death zones using tracer tests by empiric models as Wolf-Resnick and Dispersion in evaluate bed-packed reactors with horizontal subsurface flow, as a model of a constructed wetland. In order to assess the hydraulic behavior of systems such as packed-bed reactors and constructed wetlands both of subsurface flow, it is necessary to study and evaluate them modifying some variables while others remain constant. As well it is important to use mathematical models to describe, as precise as possible, the different phenomenon inside the systems, in such a way that these models bring information in an integral way to predict the behavior of the systems. (Author)
Directory of Open Access Journals (Sweden)
Petr Pelikán
2016-01-01
Full Text Available The paper is focused on a hydraulic problem of water overfall on hydrotechnic structures, especially outlets and spillways of water reservoirs. The main parameter of such structures is its discharge capacity depending on overfall coefficient, dimensions of spillway, gravitational constant and height of overflowing water jet. The aim of investigation was the mathematical derivation of formula for calculation of overfall coefficient for sharp-crested spillway from observed data. The problem was solved with the aid of statistical method of nonlinear regression analysis, Gauss-Newton algorithm (nonlinear least squares. The objective of investigation was achieved by the design of new equation providing high confidential results.
Dalla Valle, Nicolas; Wutzler, Thomas; Meyer, Stefanie; Potthast, Karin; Michalzik, Beate
2017-04-01
Dual-permeability type models are widely used to simulate water fluxes and solute transport in structured soils. These models contain two spatially overlapping flow domains with different parameterizations or even entirely different conceptual descriptions of flow processes. They are usually able to capture preferential flow phenomena, but a large set of parameters is needed, which are very laborious to obtain or cannot be measured at all. Therefore, model inversions are often used to derive the necessary parameters. Although these require sufficient input data themselves, they can use measurements of state variables instead, which are often easier to obtain and can be monitored by automated measurement systems. In this work we show a method to estimate soil hydraulic parameters from high frequency soil moisture time series data gathered at two different measurement depths by inversion of a simple one dimensional dual-permeability model. The model uses an advection equation based on the kinematic wave theory to describe the flow in the fracture domain and a Richards equation for the flow in the matrix domain. The soil moisture time series data were measured in mesocosms during sprinkling experiments. The inversion consists of three consecutive steps: First, the parameters of the water retention function were assessed using vertical soil moisture profiles in hydraulic equilibrium. This was done using two different exponential retention functions and the Campbell function. Second, the soil sorptivity and diffusivity functions were estimated from Boltzmann-transformed soil moisture data, which allowed the calculation of the hydraulic conductivity function. Third, the parameters governing flow in the fracture domain were determined using the whole soil moisture time series. The resulting retention functions were within the range of values predicted by pedotransfer functions apart from very dry conditions, where all retention functions predicted lower matrix potentials
Teaching Chemistry with Electron Density Models
Shusterman, Gwendolyn P.; Shusterman, Alan J.
1997-07-01
Linus Pauling once said that a topic must satisfy two criteria before it can be taught to students. First, students must be able to assimilate the topic within a reasonable amount of time. Second, the topic must be relevant to the educational needs and interests of the students. Unfortunately, the standard general chemistry textbook presentation of "electronic structure theory", set as it is in the language of molecular orbitals, has a difficult time satisfying either criterion. Many of the quantum mechanical aspects of molecular orbitals are too difficult for most beginning students to appreciate, much less master, and the few applications that are presented in the typical textbook are too limited in scope to excite much student interest. This article describes a powerful new method for teaching students about electronic structure and its relevance to chemical phenomena. This method, which we have developed and used for several years in general chemistry (G.P.S.) and organic chemistry (A.J.S.) courses, relies on computer-generated three-dimensional models of electron density distributions, and largely satisfies Pauling's two criteria. Students find electron density models easy to understand and use, and because these models are easily applied to a broad range of topics, they successfully convey to students the importance of electronic structure. In addition, when students finally learn about orbital concepts they are better prepared because they already have a well-developed three-dimensional picture of electronic structure to fall back on. We note in this regard that the types of models we use have found widespread, rigorous application in chemical research (1, 2), so students who understand and use electron density models do not need to "unlearn" anything before progressing to more advanced theories.
Analysis of and H∞ Controller Design For An Electro-Hydraulic Servo Pressure Regulator
DEFF Research Database (Denmark)
Stubkier, Søren; Pedersen, Henrik C.; Andersen, Torben Ole;
2011-01-01
-circuit pumps are still hydraulically controlled, there is however still a need for being able to generate a hydraulic pilot pressure. The focus of the current paper is on the analysis and controller design of an electrohydraulic servo pressure regulator, which generates a hydraulic LS-pressure for a variable......Currently mobile hydraulics is in a transition phase, where electronic sensors and digital signal processors are becoming standard on a high number of machines, hereby replacing hydraulic pilot lines and offering new possibilities with regard to both control and feasibility. As most open...... displacement pump based on an electrical reference. The paper first presents the considered system and an experimentally verified model of this. A linearized model and a stability analysis is then presented, based on which an H∞control strategy is selected. A nominal performance and a robustly stable...
Design and Optimization of Fast Switching Valves for Large Scale Digital Hydraulic Motors
DEFF Research Database (Denmark)
Roemer, Daniel Beck
of seat valves suitable for large scale digital hydraulic motors and detailed analysis methods for the pressure chambers of such machines. In addition, modeling methods of seat valves within this field have been developed, and a design method utilizing these models including optimization of subdomains has......The present thesis is on the design, analysis and optimization of fast switching valves for digital hydraulic motors with high power ratings. The need for such high power motors origins in the potential use of hydrostatic transmissions in wind turbine drive trains, as digital hydraulic machines...... have been shown to improve the overall efficiency and efficient operation range compared to traditional hydraulic machines. Digital hydraulic motors uses electronically controlled independent seat valves connected to the pressure chambers, which must be fast acting and exhibit low pressure losses...
Energy Technology Data Exchange (ETDEWEB)
Reis, Patricia A.L.; Costa, Antonella L.; Hamers, Adolfo R.; Pereira, Claubia; Rodrigues, Thiago D.A.; Mantecon, Javier G.; Veloso, Maria A.F., E-mail: patricialire@yahoo.com.br, E-mail: antonella@nuclear.ufmg.br, E-mail: adolforomerohamers@hotmail.com, E-mail: claubia@nuclear.ufmg.br, E-mail: thiagodanielbh@gmail.com, E-mail: mantecon1987@gmail.com, E-mail: dora@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Instituto Nacional de Ciencias e Tecnologia de Reatores Nucleares Inovadores (INCT/CNPq), Belo Horizonte (Brazil); Miro, Rafael; Verdu, Gumersindo, E-mail: rmiro@iqn.upv.es, E-mail: gverdu@iqn.upv.es [Universidad Politecnica de Valencia (Spain). Departamento de Ingenieria Quimica y Nuclear
2015-07-01
The computational advances observed in the last two decades have been provided direct impact on the researches related to nuclear simulations, which use several types of computer codes, including coupled between them, allowing representing with very accuracy the behavior of nuclear plants. Studies of complex scenarios in nuclear reactors have been improved by the use of thermal-hydraulic (TH) and neutron kinetics (NK) coupled codes. This technique consists in incorporating three-dimensional (3D) neutron modeling of the reactor core into codes, mainly to simulate transients that involve asymmetric core spatial power distributions and strong feedback effects between neutronics and reactor thermal-hydraulics. Therefore, this work presents preliminary results of TH RELAP5 and the NK PARCS calculations applied to model of the Angra 2 reactor. The WIMSD-5B code has been used to generate the macroscopic cross sections used in the NK code. The results obtained are satisfactory and represent important part of the development of this methodology. The next step is to couple the codes. (author)
Perkins, Kimberlie; Johnson, Brittany D.; Mirus, Benjamin B.
2014-01-01
Operations at the Idaho National Laboratory (INL) have the potential to contaminate the underlying Eastern Snake River Plain (ESRP) aquifer. Methods to quantitatively characterize unsaturated flow and recharge to the ESRP aquifer are needed to inform water-resources management decisions at INL. In particular, hydraulic properties are needed to parameterize distributed hydrologic models of unsaturated flow and transport at INL, but these properties are often difficult and costly to obtain for large areas. The unsaturated zone overlying the ESRP aquifer consists of alternating sequences of thick fractured volcanic rocks that can rapidly transmit water flow and thinner sedimentary interbeds that transmit water much more slowly. Consequently, the sedimentary interbeds are of considerable interest because they primarily restrict the vertical movement of water through the unsaturated zone. Previous efforts by the U.S. Geological Survey (USGS) have included extensive laboratory characterization of the sedimentary interbeds and regression analyses to develop property-transfer models, which relate readily available physical properties of the sedimentary interbeds (bulk density, median particle diameter, and uniformity coefficient) to water retention and unsaturated hydraulic conductivity curves.
Vafi, Kourosh; Brandt, Adam
2016-07-19
This paper introduces GHGfrack, an open-source engineering-based model that estimates energy consumption and associated GHG emissions from drilling and hydraulic fracturing operations. We describe verification and calibration of GHGfrack against field data for energy and fuel consumption. We run GHGfrack using data from 6927 wells in Eagle Ford and 4431 wells in Bakken oil fields. The average estimated energy consumption in Eagle Ford wells using lateral hole diameters of 8 (3)/4 and 6 (1)/8 in. are 2.25 and 2.73 TJ/well, respectively. The average estimated energy consumption in Bakken wells using hole diameters of 6 in. for horizontal section is 2.16 TJ/well. We estimate average greenhouse gas (GHG) emissions of 419 and 510 tonne of equivalent CO2 per well (tonne of CO2 eq/well) for the two aforementioned assumed geometries in Eagle Ford, respectively, and 417 tonne of CO2 eq/well for the case of Bakken. These estimates are limited only to GHG emissions from combustion of diesel fuel to supply energy only for rotation of drill string, drilling mud circulation, and fracturing pumps. Sensitivity analysis of the model shows that the top three key variables in driving energy intensity in drilling are the lateral hole diameter, drill pipe internal diameter, and mud flow rate. In hydraulic fracturing, the top three are lateral casing diameter, fracturing fluid volume, and length of the lateral.
Energy Technology Data Exchange (ETDEWEB)
Badea, Aurelian F., E-mail: aurelian.badea@kit.edu [Karlsruhe Institute of Technology, Vincenz-Prießnitz-Str. 3, 76131 Karlsruhe (Germany); Cacuci, Dan G. [Center for Nuclear Science and Energy/Dept. of ME, University of South Carolina, 300 Main Street, Columbia, SC 29208 (United States)
2017-03-15
Highlights: • BWR Turbine Trip 2 (BWR-TT2) benchmark. • Substantial (up to 50%) reduction of uncertainties in the predicted transient power. • 6660 uncertain model parameters were calibrated. - Abstract: By applying a comprehensive predictive modeling methodology, this work demonstrates a substantial (up to 50%) reduction of uncertainties in the predicted total transient power in the BWR Turbine Trip 2 (BWR-TT2) benchmark while calibrating the numerical simulation of this benchmark, comprising 6090 macroscopic cross sections, and 570 thermal-hydraulics parameters involved in modeling the phase-slip correlation, transient outlet pressure, and total mass flow. The BWR-TT2 benchmark is based on an experiment that was carried out in 1977 in the NPP Peach Bottom 2, involving the closure of the turbine stop valve which caused a pressure wave that propagated with attenuation into the reactor core. The condensation of the steam in the reactor core caused by the pressure increase led to a positive reactivity insertion. The subsequent rise of power was limited by the feedback and the insertion of the control rods. The BWR-TT2 benchmark was modeled with the three-dimensional reactor physics code system DYN3D, by coupling neutron kinetics with two-phase thermal-hydraulics. All 6660 DYN3D model parameters were calibrated by applying a predictive modeling methodology that combines experimental and computational information to produce optimally predicted best-estimate results with reduced predicted uncertainties. Simultaneously, the predictive modeling methodology yields optimally predicted values for the BWR total transient power while reducing significantly the accompanying predicted standard deviations.
DEFF Research Database (Denmark)
Vasquez, Vicente; Thomsen, Anton Gårde; Iversen, Bo Vangsø;
them have been reported. To compare among methods, one year of four large-scale lysimeters drainage (D) was evaluated against modeled soil deep percolation using either profile soil moisture, bromide breakthrough curves from suction cups, or measured soil hydraulic properties in the laboratory...... model using field q, and 572 mm with the laboratory measured soil hydraulic properties. In conclusion, lysimeters presented the lowest D and can be considered as a lower bound for D; whereas either laboratory measured soil hydraulic properties or models calibrated with profile soil moisture yielded......Quantifying recharge to shallow aquifers via soil deep percolation is needed for sustainable management of water resources. This includes modeled predictions to address the effects of climate change on recharge. Different methods to estimate soil deep percolation exist but few comparisons among...
Wood, M.; Neal, J. C.; Hostache, R.; Corato, G.; Chini, M.; Giustarini, L.; Matgen, P.; Wagener, T.; Bates, P. D.
2015-12-01
Synthetic Aperture Radar (SAR) satellites are capable of all-weather day and night observations that can discriminate between land and smooth open water surfaces over large scales. Because of this there has been much interest in the use of SAR satellite data to improve our understanding of water processes, in particular for fluvial flood inundation mechanisms. Past studies prove that integrating SAR derived data with hydraulic models can improve simulations of flooding. However while much of this work focusses on improving model channel roughness values or inflows in ungauged catchments, improvement of model bathymetry is often overlooked. The provision of good bathymetric data is critical to the performance of hydraulic models but there are only a small number of ways to obtain bathymetry information where no direct measurements exist. Spatially distributed river depths are also rarely available. We present a methodology for calibration of model average channel depth and roughness parameters concurrently using SAR images of flood extent and a Sub-Grid model utilising hydraulic geometry concepts. The methodology uses real data from the European Space Agency's archive of ENVISAT[1] Wide Swath Mode images of the River Severn between Worcester and Tewkesbury during flood peaks between 2007 and 2010. Historic ENVISAT WSM images are currently free and easy to access from archive but the methodology can be applied with any available SAR data. The approach makes use of the SAR image processing algorithm of Giustarini[2] et al. (2013) to generate binary flood maps. A unique feature of the calibration methodology is to also use parameter 'identifiability' to locate the parameters with higher accuracy from a pre-assigned range (adopting the DYNIA method proposed by Wagener[3] et al., 2003). [1] https://gpod.eo.esa.int/services/ [2] Giustarini. 2013. 'A Change Detection Approach to Flood Mapping in Urban Areas Using TerraSAR-X'. IEEE Transactions on Geoscience and Remote
Abdelbaki, Chérifa; Benchaib, Mohamed Mouâd; Benziada, Salim; Mahmoudi, Hacène; Goosen, Mattheus
2016-04-01
For more effective management of water distribution network in an arid region, Mapinfo GIS (8.0) software was coupled with a hydraulic model (EPANET 2.0) and applied to a case study region, Chetouane, situated in the north-west of Algeria. The area is characterized not only by water scarcity but also by poor water management practices. The results showed that a combination of GIS and modeling permits network operators to better analyze malfunctions with a resulting more rapid response as well as facilitating in an improved understanding of the work performed on the network. The grouping of GIS and modeling as an operating tool allows managers to diagnosis a network, to study solutions of problems and to predict future situations. The later can assist them in making informed decisions to ensure an acceptable performance level for optimal network operation.
Abdelbaki, Chérifa; Benchaib, Mohamed Mouâd; Benziada, Salim; Mahmoudi, Hacène; Goosen, Mattheus
2017-06-01
For more effective management of water distribution network in an arid region, Mapinfo GIS (8.0) software was coupled with a hydraulic model (EPANET 2.0) and applied to a case study region, Chetouane, situated in the north-west of Algeria. The area is characterized not only by water scarcity but also by poor water management practices. The results showed that a combination of GIS and modeling permits network operators to better analyze malfunctions with a resulting more rapid response as well as facilitating in an improved understanding of the work performed on the network. The grouping of GIS and modeling as an operating tool allows managers to diagnosis a network, to study solutions of problems and to predict future situations. The later can assist them in making informed decisions to ensure an acceptable performance level for optimal network operation.
DEFF Research Database (Denmark)
Conrad, Finn
2005-01-01
The paper presents research results using IT-Tools for CAD and dynamic modelling, simulation, analysis, and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. Matlab/Simulink and CATIA are used as IT-Tools. The contributions include results from on-going...
Elshamy, M.; Pietroniro, A.; Wheater, H. S.
2016-12-01
Accurate simulation of river streamflow is essential for water resources management and climate change impact studies. Hydrological models often route the streamflow using simple hydrological routing techniques that does not consider the characteristics of river channels or complex morphology present in certain rivers. Yet, for large river systems, as well as for regional and global modelling, routing effects can have a very significant impact on the magnitude of flood peaks and the timing of flows to seas and oceans. In this study, an approach to couple the MESH (Modélisation Environmentale Communautaire-Surface and Hydrology) model, which embeds the Canadian land surface scheme (CLASS), with a one-dimensional river hydraulic model (River-1D) of the main Mackenzie river and the 3 of its main tributaries (Peace, Athabasca, and Slave) is reported. Of particular interest is ensuring the complexity of dealing with the large delta environment where flow reversal and overbank storage is possible and can be a significant part of the water budget. Inflows at designated locations on those rivers are generated by the MESH hydrologic model run at 0.125° spatial resolution and 30 minutes temporal resolution. The one-dimensional hydraulic model simulates the routing along the river in a one-way coupling mode with due consideration to river ice processes including freeze-up and break-up. This approach improves the accuracy of river flow simulations along the main stem of the Mackenzie and its main tributes and allows for studying sediment transport and dynamic events, such as dam breaches or ice jam release and formation events.
Manners, R.; Schmidt, J. C.; Wheaton, J. M.
2011-12-01
An enduring question in geomorphology is the role of riparian vegetation in inducing or exacerbating channel narrowing. It is typically difficult to isolate the role of vegetation in causing channel narrowing, because narrowing typically occurs where there are changes in stream flow, sediment supply, the invasion of non-native vegetation, and sometimes climate change. Therefore, linkages between changes in vegetation communities and changes in channel form are often difficult to identify. We took a mechanistic approach to isolate the role of the invasive riparian shrub tamarisk (Tamarix spp) in influencing channel narrowing in the Colorado River basin. Detailed geomorphic reconstructions of two sites on the Yampa and Green Rivers, respectively, in Dinosaur National Monument show that channel narrowing has been progressive and that tamarisk encroachment has also occurred; at the same time, dams have been constructed, diversions increased, and spring snowmelt runoff has been occurring earlier in spring. We simulated hydraulic and sediment transport conditions during the two largest floods of record -- 1984 and 2011. Two-dimensional hydraulic models were built to reflect these conditions and allowed us to perform sensitivity tests to determine the dominant determinants of the observed patterns of erosion and deposition. Channel and floodplain topography were constrained through detailed stratigraphic analysis, including precise dating of deposits based on dating of buried tamarisk plants in a series of floodplain trenches and pits. We also used historical air photos to establish past channel topography. To parameterize the influence of riparian vegetation, we developed a model that links detailed terrestrial laser scan (TLS) measurements of stand structure and its corresponding hydraulic roughness at the patch scale to reach-scale riparian vegetation patterns determined from airborne LiDaR (ALS). This model, in conjunction with maps of the ages and establishment
Itinerant electron model and conductance of DNA
Institute of Scientific and Technical Information of China (English)
Zhen QU; Da-wei KANG; Xu-tuan GAO; Shi-jie XIE
2008-01-01
DNA (Deoxyribonucleic acid) has recently caught the attention of chemists and physicists.A major reason for this interest is DNA's potential use in nanoelectronie devices,both as a template for assembling nanocireuits and as an element of such circuits.However,the electronic properties of the DNA molecule remain very controversial. Charge-transfer reactions and conductivity measurements show a large variety of possible electronic behavior,ranging from Anderson and bandgap insulators to effective molecular wires and induced superconductors.In this review article,we summarize the wide-ranging experimental and theoretical results of charge transport in DNA.An itinerant electron model is suggested and the effect of the density of itinerant electrons on the conductivity of DNA is studied.Calculations show that a DNA molecule may show conductivity from insulating to metallic,which explains the controversial and profuse electric characteristics of DNA to some extent.
Radiation Belt Electron Dynamics: Modeling Atmospheric Losses
Selesnick, R. S.
2003-01-01
The first year of work on this project has been completed. This report provides a summary of the progress made and the plan for the coming year. Also included with this report is a preprint of an article that was accepted for publication in Journal of Geophysical Research and describes in detail most of the results from the first year of effort. The goal for the first year was to develop a radiation belt electron model for fitting to data from the SAMPEX and Polar satellites that would provide an empirical description of the electron losses into the upper atmosphere. This was largely accomplished according to the original plan (with one exception being that, for reasons described below, the inclusion of the loss cone electrons in the model was deferred). The main concerns at the start were to accurately represent the balance between pitch angle diffusion and eastward drift that determines the dominant features of the low altitude data, and then to accurately convert the model into simulated data based on the characteristics of the particular electron detectors. Considerable effort was devoted to achieving these ends. Once the model was providing accurate results it was applied to data sets selected from appropriate periods in 1997, 1998, and 1999. For each interval of -30 to 60 days, the model parameters were calculated daily, thus providing good short and long term temporal resolution, and for a range of radial locations from L = 2.7 to 3.9. .
Hydraulic Press CAD System Based on 3D Feature Modeling Technology%基于三维特征建模的液压机CAD系统
Institute of Scientific and Technical Information of China (English)
张涛
2011-01-01
在分析目前单柱式液压机CAD设计应用的基础上，提出引入实例推理原理和三维特征建模的参数化设计体系结构，应用特征建模技术建立模型，实现液压机主要结构的三维设计。%Based on the analysis of application situation of the design of hydraulic press, this paper presents the structure of hydraulic press system design with Case-based Reasoning principle and parametric design based on 3D feature modeling. The action of main function is also discussed. The models are established by using the technology of feature modeling, and the 3D design of hydraulic press is realized.
Profit, Matthew; Dutko, Martin; Yu, Jianguo; Cole, Sarah; Angus, Doug; Baird, Alan
2016-04-01
This paper presents a novel approach to predict the propagation of hydraulic fractures in tight shale reservoirs. Many hydraulic fracture modelling schemes assume that the fracture direction is pre-seeded in the problem domain discretisation. This is a severe limitation as the reservoir often contains large numbers of pre-existing fractures that strongly influence the direction of the propagating fracture. To circumvent these shortcomings, a new fracture modelling treatment is proposed where the introduction of discrete fracture surfaces is based on new and dynamically updated geometrical entities rather than the topology of the underlying spatial discretisation. Hydraulic fracturing is an inherently coupled engineering problem with interactions between fluid flow and fracturing when the stress state of the reservoir rock attains a failure criterion. This work follows a staggered hydro-mechanical coupled finite/discrete element approach to capture the key interplay between fluid pressure and fracture growth. In field practice, the fracture growth is hidden from the design engineer and microseismicity is often used to infer hydraulic fracture lengths and directions. Microseismic output can also be computed from changes of the effective stress in the geomechanical model and compared against field microseismicity. A number of hydraulic fracture numerical examples are presented to illustrate the new technology.
Directory of Open Access Journals (Sweden)
Esch Markus
2014-01-01
Full Text Available For future high temperature reactor projects, e. g., for electricity production or nuclear process heat applications, the steam generator is a crucial component. A typical design is a helical coil steam generator consisting of several tubes connected in parallel forming cylinders of different diameters. This type of steam generator was a significant component used at the thorium high temperature reactor. In the work presented the temperature profile is being analyzed by the nodal thermal hydraulics code TRACE for the thorium high temperature reactor steam generator. The influence of the nodalization is being investigated within the scope of this study and compared to experimental results from the past. The results of the standard TRACE code are compared to results using a modified Nusselt number for the primary side. The implemented heat transfer correlation was developed within the past German HTR program. This study shows that both TRACE versions are stable and provides a discussion of the nodalization requirements.
Energy Technology Data Exchange (ETDEWEB)
KALINICHENKO,S.D.KROSHILIN,A.E.KROSHILIN,V.E.SMIRNOV,A.V.KOHUT,P.
2004-03-15
In this paper we present verification results of the BAGIRA code that was performed using data from integral thermal-hydraulic experimental test facilities as well as data obtained from operating nuclear power plants. BAGIRA is a three-dimensional numerical best-estimate code that includes non-homogeneous modeling. Special consideration was given to the recently completed experimental data from the PSB-VVER integral test facility (EREC, Electrogorsk, Russia)--a new Russian large-scale four-loop unit, which has been designed to model the primary circuits of VVER-1000 type reactors. It is demonstrated that the code BAGIRA can be used to analyze nuclear reactor behavior under normal and accident conditions.
Electron Correlation Models for Optical Activity
DEFF Research Database (Denmark)
Höhn, E. G.; O. E. Weigang, Jr.
1968-01-01
A two-system no-overlap model for rotatory strength is developed for electric-dipole forbidden as well as allowed transitions. General equations which allow for full utilization of symmetry in the chromophore and in the environment are obtained. The electron correlation terms are developed in full...
Kutílek, M; Jendele, L; Krejca, M
2009-02-16
The accelerated flow in soil pores is responsible for a rapid transport of pollutants from the soil surface to deeper layers up to groundwater. The term preferential flow is used for this type of transport. Our study was aimed at the preferential flow realized in the structural porous domain in bi-modal soils. We compared equations describing the soil water retention function h(theta) and unsaturated hydraulic conductivity K(h), eventually K(theta) modified for bi-modal soils, where theta is the soil water content and h is the pressure head. The analytical description of a curve passing experimental data sets of the soil hydraulic function is typical for the empirical equation characterized by fitting parameters only. If the measured data are described by the equation derived by the physical model without using fitting parameters, we speak about a physically based model. There exist several transitional subtypes between empirical and physically based models. They are denoted as semi-empirical, or semi-physical. We tested 3 models of soil water retention function and 3 models of unsaturated conductivity using experimental data sets of sand, silt, silt loam and loam. All used soils are typical by their bi-modality of the soil porous system. The model efficiency was estimated by RMSE (Root mean square error) and by RSE (Relative square error). The semi-empirical equation of the soil water retention function had the lowest values of RMSE and RSE and was qualified as "optimal" for the formal description of the shape of the water retention function. With this equation, the fit of the modelled data to experiments was the closest one. The fitting parameters smoothed the difference between the model and the physical reality of the soil porous media. The physical equation based upon the model of the pore size distribution did not allow exact fitting of the modelled data to the experimental data due to the rigidity and simplicity of the physical model when compared to the
Trapped Electron Model 2 (TEM-2)
2010-04-25
Ginet (AFRL and MIT/Lincoln Lab). We made extensive use of the IRBEM (formerly ONERA ) library of magnetic field models and field line tracing...several others. We are aware of other efforts to develop reanalysis models of the electron radiation belts. One effort, at ONERA (Office National...sensors on GPS and geosynchronous (GEO) satellites, the ONERA group has obtained promising results, including a first physics-based data
Congsheng Fu; Guiling Wang; Michael L. Goulden; Russell L. Scott; Kenneth Bible; Zoe G. Cardon
2016-01-01
Effects of hydraulic redistribution (HR) on hydrological, biogeochemical, and ecological processes have been demonstrated in the field, but the current generation of standard earth system models does not include a representation of HR. Though recent studies have examined the effect of incorporating HR into land surface models, few (if any) have done cross-site...
Geologically based model of heterogeneous hydraulic conductivity in an alluvial setting
Fogg, Graham E.; Noyes, Charles D.; Carle, Steven F.
Information on sediment texture and spatial continuity are inherent to sedimentary depositional facies descriptions, which are therefore potentially good predictors of spatially varying hydraulic conductivity (K). Analysis of complex alluvial heterogeneity in Livermore Valley, California, USA, using relatively abundant core descriptions and field pumping-test data, demonstrates a depositional-facies approach to characterization of subsurface heterogeneity. Conventional textural classifications of the core show a poor correlation with K; however, further refinement of the textural classifications into channel, levee, debris-flow, and flood-plain depositional facies reveals a systematic framework for spatial modeling of K. This geologic framework shows that most of the system is composed of very low-K flood-plain materials, and that the K measurements predominantly represent the other, higher-K facies. Joint interpretation of both the K and geologic data shows that spatial distribution of K in this system could not be adequately modeled without geologic data and analysis. Furthermore, it appears that K should not be assumed to be log-normally distributed, except perhaps within each facies. Markov chain modeling of transition probability, representing spatial correlation within and among the facies, captures the relevant geologic features while highlighting a new approach for statistical characterization of hydrofacies spatial variability. The presence of fining-upward facies sequences, cross correlation between facies, as well as other geologic attributes captured by the Markov chains provoke questions about the suitability of conventional geostatistical approaches based on variograms or covariances for modeling geologic heterogeneity. Résumé Les informations sur la texture des sédiments et leur continuité spatiale font partie des descriptions de faciès sédimentaires de dépôt. Par conséquent, ces descriptions sont d'excellents prédicteurs potentiels des
DEFF Research Database (Denmark)
Conrad, Finn; Pobedza, J.; Sobczyk, A.
2003-01-01
The paper presents experimental-based modelling, simulation, analysis and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. The contributions includes results from on-going research projects on fluid power and mechatronics based on tap water hydraulic...... proportional valves and servo actuators for motion control and power transmission undertaken in co-operation by Technical University, DTU and Cracow University of Technology, CUT. The results of this research co-operation include engineering design and test of simulation models compared with two mechatronic...
Mathematical model I. Electron and quantum mechanics
Gadre, Nitin Ramchandra
2011-03-01
The basic particle electron obeys various theories like electrodynamics, quantum mechanics and special relativity. Particle under different experimental conditions behaves differently, allowing us to observe different characteristics which become basis for these theories. In this paper, we have made an attempt to suggest a classical picture by studying the requirements of these three modern theories. The basic presumption is: There must be certain structural characteristics in a particle like electron which make it obey postulates of modern theories. As it is `difficult' to find structure of electron experimentally, we make a mathematical attempt. For a classical approach, we require well defined systems and we have studied a system with two charged particles, proton and electron in a hydrogen atom. An attempt has been made to give a model to describe electron as seen by the proton. We then discuss how the model can satisfy the requirements of the three modern theories in a classical manner. The paper discusses basic aspects of relativity and electrodynamics. However the focus of the paper is on quantum mechanics.
Mathematical model I. Electron and quantum mechanics
Directory of Open Access Journals (Sweden)
Nitin Ramchandra Gadre
2011-03-01
Full Text Available The basic particle electron obeys various theories like electrodynamics, quantum mechanics and special relativity. Particle under different experimental conditions behaves differently, allowing us to observe different characteristics which become basis for these theories. In this paper, we have made an attempt to suggest a classical picture by studying the requirements of these three modern theories. The basic presumption is: There must be certain structural characteristics in a particle like electron which make it obey postulates of modern theories. As it is ‘difficult’ to find structure of electron experimentally, we make a mathematical attempt. For a classical approach, we require well defined systems and we have studied a system with two charged particles, proton and electron in a hydrogen atom. An attempt has been made to give a model to describe electron as seen by the proton. We then discuss how the model can satisfy the requirements of the three modern theories in a classical manner. The paper discusses basic aspects of relativity and electrodynamics. However the focus of the paper is on quantum mechanics.
Barani, Hamidreza Rostami; Lashkaripour, Gholamreza; Ghafoori, Mohammad
2014-08-01
In the present study, a new model is proposed to predict the permeability per fracture in the fault zones by a new parameter named joint hydraulic factor (JH). JH is obtained from Water Pressure Test (WPT) and modified by the degree of fracturing. The results of JH correspond with quantitative fault zone descriptions, qualitative fracture, and fault rock properties. In this respect, a case study was done based on the data collected from Seyahoo dam site located in the east of Iran to provide the permeability prediction model of fault zone structures. Datasets including scan-lines, drill cores, and water pressure tests in the terrain of Andesite and Basalt rocks were used to analyse the variability of in-site relative permeability of a range from fault zones to host rocks. The rock mass joint permeability quality, therefore, is defined by the JH. JH data analysis showed that the background sub-zone had commonly core had permeability characteristics nearly as low as the outer damage zone, represented by 8 Lu (1.3 ×10-4 m 3/s) per fracture, with occasional peaks towards 12 Lu (2 ×10-4 m 3/s) per fracture. The maximum JH value belongs to the inner damage zone, marginal to the fault core, with 14-22 Lu (2.3 ×10-4-3.6 ×10-4 m 3/s) per fracture, locally exceeding 25 Lu (4.1 ×10-4 m 3/s) per fracture. This gives a proportional relationship for JH approximately 1:4:2 between the fault core, inner damage zone, and outer damage zone of extensional fault zones in crystalline rocks. The results of the verification exercise revealed that the new approach would be efficient and that the JH parameter is a reliable scale for the fracture permeability change. It can be concluded that using short duration hydraulic tests (WPTs) and fracture frequency (FF) to calculate the JH parameter provides a possibility to describe a complex situation and compare, discuss, and weigh the hydraulic quality to make predictions as to the permeability models and permeation amounts of different
Indian Academy of Sciences (India)
Hamidreza Rostami Barani; Gholamreza Lashkaripour; Mohammad Ghafoori
2014-08-01
In the present study, a new model is proposed to predict the permeability per fracture in the fault zones by a new parameter named joint hydraulic factor (JH). JH is obtained from Water Pressure Test WPT) and modified by the degree of fracturing. The results of JH correspond with quantitative fault zone descriptions, qualitative fracture, and fault rock properties. In this respect, a case study was done based on the data collected from Seyahoo dam site located in the east of Iran to provide the permeability prediction model of fault zone structures. Datasets including scan-lines, drill cores, and water pressure tests in the terrain of Andesite and Basalt rocks were used to analyse the variability of in-site relative permeability of a range from fault zones to host rocks. The rock mass joint permeability quality, therefore, is defined by the JH. JH data analysis showed that the background sub-zone had commonly > 3 Lu (less of 5 × 10−5 m3/s) per fracture, whereas the fault core had permeability characteristics nearly as low as the outer damage zone, represented by 8 Lu (1.3 × 10−4 m3/s) per fracture, with occasional peaks towards 12 Lu (2 × 10−4 m3/s) per fracture. The maximum JH value belongs to the inner damage zone, marginal to the fault core, with 14–22 Lu (2.3 × 10−4 –3.6 × 10−4 m3/s) per fracture, locally exceeding 25 Lu (4.1 × 10−4 m3/s) per fracture. This gives a proportional relationship for JH approximately 1:4:2 between the fault core, inner damage zone, and outer damage zone of extensional fault zones in crystalline rocks. The results of the verification exercise revealed that the new approach would be efficient and that the JH parameter is a reliable scale for the fracture permeability change. It can be concluded that using short duration hydraulic tests (WPTs) and fracture frequency (FF) to calculate the JH parameter provides a possibility to describe a complex situation and compare, discuss, and weigh the hydraulic quality to make
Energy Technology Data Exchange (ETDEWEB)
Zhou, Jing [Idaho National Lab. (INL), Idaho Falls, ID (United States); Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mattson, Earl [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Herb F. [Univ. of Wisconsin, Madison, WI (United States); Haimson, Bezalel C. [Univ. of Wisconsin, Madison, WI (United States); Doe, Thomas W. [Golder Associates Inc., Redmond, VA (United States); Oldenburg, Curtis M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dobson, Patrick F. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2017-02-01
Aimed at supporting the design of hydraulic fracturing experiments at the kISMET site, ~1500 m below ground in a deep mine, we performed pre-experimental hydraulic fracturing simulations in order to estimate the breakdown pressure, propagation pressure, fracture geometry, and the magnitude of induced seismicity using a newly developed fully coupled three-dimensional (3D) network flow and quasi-static discrete element model (DEM). The quasi-static DEM model, which is constructed by Delaunay tessellation of the rock volume, considers rock fabric heterogeneities by using the “disordered” DEM mesh and adding random perturbations to the stiffness and tensile/shear strengths of individual DEM elements and the elastic beams between them. A conjugate 3D flow network based on the DEM lattice is constructed to calculate the fluid flow in both the fracture and porous matrix. One distinctive advantage of the model is that fracturing is naturally described by the breakage of elastic beams between DEM elements. It is also extremely convenient to introduce mechanical anisotropy into the model by simply assigning orientation-dependent tensile/shear strengths to the elastic beams. In this paper, the 3D hydraulic fracturing model was verified against the analytic solution for a penny-shaped crack model. We applied the model to simulate fracture propagation from a vertical open borehole based on initial estimates of rock mechanical properties and in-situ stress conditions. The breakdown pressure and propagation pressure are directly obtained from the simulation. In addition, the released elastic strain energies of individual fracturing events were calculated and used as a conservative estimate for the magnitudes of the potential induced seismic activities associated with fracturing. The comparisons between model predictions and experimental results are still ongoing.
Model Order Reduction for Electronic Circuits:
DEFF Research Database (Denmark)
Hjorth, Poul G.; Shontz, Suzanne
Electronic circuits are ubiquitous; they are used in numerous industries including: the semiconductor, communication, robotics, auto, and music industries (among many others). As products become more and more complicated, their electronic circuits also grow in size and complexity. This increased ...... in the semiconductor industry. Circuit simulation proceeds by using Maxwell’s equations to create a mathematical model of the circuit. The boundary element method is then used to discretize the equations, and the variational form of the equations are then solved on the graph network....
Energy Technology Data Exchange (ETDEWEB)
Guerrero Angulo, Jose Oscar [Universidad Autonoma de Sinaloa (Mexico); Arreguin Cortes, Felipe [Instituto Mexicano de Tecnologia del Agua, Jiutepec, Morelos (Mexico)
2002-03-01
This paper presents a hydraulic simulation model for drinking water networks, including elements that are currently not considered household connections, spatially variable flowrate distribution pipelines, and tee secondary network. This model is determined by solving the equations needed for a conventional model following an indirect procedure for the solution of large equations systems. Household connection performance is considered as dependent of water pressure and the way in which users operate the taps of such intakes. This approach allows a better a acquaintance with the drinking water supply networks performance as well as solving problems that demand a more precise hydraulic simulation, such as water quality variations, leaks in networks, and the influence of home water tanks as regulating devices. [Spanish] Se presenta un modelo de simulacion hidraulica para redes de agua potable en el cual se incluyen elementos que no se toman en cuenta actualmente, como las tomas domiciliarias, los tubos de distribucion con gastos espacialmente variado y la red secundaria, resolviendo el numero de ecuaciones que seria necesario plantear en un modelo convencional mediante un procedimiento indirecto para la solucion de grandes sistemas de ecuaciones. En las tomas domiciliarias se considera que su funcionamiento depende de las presiones y la forma en que los usuarios operan las llaves de las mismas. Este planteamiento permite conocer mejor el funcionamiento de las redes de abastecimiento de agua potable y solucionar problemas que requieren de una simulacion hidraulica mas precisa, como el comportamiento de la calidad del agua, las fugas en las redes y la influencia reguladora de los tinacos de las casas.
Fernández, Alfonso; Najafi, Mohammad Reza; Durand, Michael; Mark, Bryan G.; Moritz, Mark; Jung, Hahn Chul; Neal, Jeffrey; Shastry, Apoorva; Laborde, Sarah; Phang, Sui Chian; Hamilton, Ian M.; Xiao, Ningchuan
2016-08-01
Recent innovations in hydraulic modeling have enabled global simulation of rivers, including simulation of their coupled wetlands and floodplains. Accurate simulations of floodplains using these approaches may imply tremendous advances in global hydrologic studies and in biogeochemical cycling. One such innovation is to explicitly treat sub-grid channels within two-dimensional models, given only remotely sensed data in areas with limited data availability. However, predicting inundated area in floodplains using a sub-grid model has not been rigorously validated. In this study, we applied the LISFLOOD-FP hydraulic model using a sub-grid channel parameterization to simulate inundation dynamics on the Logone River floodplain, in northern Cameroon, from 2001 to 2007. Our goal was to determine whether floodplain dynamics could be simulated with sufficient accuracy to understand human and natural contributions to current and future inundation patterns. Model inputs in this data-sparse region include in situ river discharge, satellite-derived rainfall, and the shuttle radar topography mission (SRTM) floodplain elevation. We found that the model accurately simulated total floodplain inundation, with a Pearson correlation coefficient greater than 0.9, and RMSE less than 700 km2, compared to peak inundation greater than 6000 km2. Predicted discharge downstream of the floodplain matched measurements (Nash-Sutcliffe efficiency of 0.81), and indicated that net flow from the channel to the floodplain was modeled accurately. However, the spatial pattern of inundation was not well simulated, apparently due to uncertainties in SRTM elevations. We evaluated model results at 250, 500 and 1000-m spatial resolutions, and found that results are insensitive to spatial resolution. We also compared the model output against results from a run of LISFLOOD-FP in which the sub-grid channel parameterization was disabled, finding that the sub-grid parameterization simulated more realistic
Indian Academy of Sciences (India)
M-H Shih; W-P Sung; M-J Wu
2010-10-01
A relief valve parallel to the throttle valve is added to a Velocity dependent hydraulic damper (VDHD) so that the oriﬁce size that regulates the oil ﬂow can be adjusted. This device adjustment will allow the damper to have an adaptive control of damping by changing its damping coefﬁcient. A mathematical model including a serial friction model and a small damper that is parallel to the friction model added to the Maxwell model for simulating the actual energy-dissipating behaviour of the VDHD was proposed in this research. To extend the useful value of VDHD, a numerical analysis model based on the SAP2000 nonlinear analysis program was applied to simulate the energy-dissipating characteristics of VDHD in this study. The analysis results obtained by using the mathematical model and the proposed SAP2000 numerical model conform to the seismic resistant test results, and conﬁrm that the SAP2000 nonlinear analysis program can accurately describe the actual energy-dissipating behaviour of the VDHD installed on structures under various energy-dissipating situations.
Exactly solvable models of strongly correlated electrons
Korepin, Vladimir E
1994-01-01
Systems of strongly correlated electrons are at the heart of recent developments in condensed matter theory. They have applications to phenomena like high-T c superconductivity and the fractional quantum hall effect. Analytical solutions to such models, though mainly limited to one spatial dimension, provide a complete and unambiguous picture of the dynamics involved. This volume is devoted to such solutions obtained using the Bethe Ansatz, and concentrates on the most important of such models, the Hubbard model. The reprints are complemented by reviews at the start of each chapter and an exte
HYDRAULICS, HAMPDEN COUNTY, MA, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data in this submittal include spatial datasets and model outputs necessary for computation of the 1-percent flooding extent. The minimum requirement for...
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Transporting sediment is a natural function of the river. To maintain the normal evolution of the river certain amount of water flow is required, which is called the instream flow requirements for transporting sediment (IFRTS). We defined the permitting flow velocity by the conception of IFRTS, and also put forward the ecological hydraulic radius model (EHRM) to estimate IFRTS. The calculating process of EHRM is explained by the example of Daofu Hydrological Station on Xianshui branch of Yalong River in the west line first-stage construction of South-North Water Transfer Project. The result shows that the IFRTS occupied 29.7%―59.5% of annual mean discharge in flood season, the average of IFRTS was about 100.2 m3/s during 1966―1987, it is close to the IFRTS 90 m3/s calculated by IFRTS conception. Hence, it is feasible to use EHRM to calculate IFRTS.
Modeling of high-speed electronic devices
Directory of Open Access Journals (Sweden)
V. G. Kudrya
2013-09-01
Full Text Available Introduction. The theme of this publication is the modeling of electronic tools that operate in the frequency range from zero to terahertz and higher. Application of new concepts and technologies, including biotechnology and nanotechnology in the development of monolithic integrated circuits led to a backlog of technologies of projecting from technologies and experimental research and manufacturing. The aim of this work is to develop algorithms for analysis, reflecting not only topological as well as morphological properties of the object, that is designing within the framework of accounting EMI communicational transmission of energy and information in the volume of the monolithic integrated circuit. Basic steps for constructing the algorithm. The object of design is presented in the form of basic elements, which can be combined with a communication structure. The object of design is presented in the form of basic elements, which can be combined with a communication structure. There are three types of matrix equations: component; component - communication structure; communication structure. Systems of equations are reduced to standardized descriptors of mathematical model by which to understand current of poles and voltage arcs whole set of basic elements. In this way obtained mathematical model that can be implemented in CAD nano and micro technology electronics. Conclusions. Mathematical models of analysis of high-speed digital and analog electronic means. The algorithm allows morphological optimization is to minimize the adverse effects outside the system of electromagnetic interaction between the components and communicator.
Directory of Open Access Journals (Sweden)
Andres San-Millan
2017-08-01
Full Text Available In this paper a two-input, two-output (TITO fractional order mathematical model of a laboratory prototype of a hydraulic canal is proposed. This canal is made up of two pools that have a strong interaction between them. The inputs of the TITO model are the pump flow and the opening of an intermediate gate, and the two outputs are the water levels in the two pools. Based on the experiments developed in a laboratory prototype the parameters of the mathematical models have been identified. Then, considering the TITO model, a first control loop of the pump is closed to reproduce real-world conditions in which the water level of the first pool is not dependent on the opening of the upstream gate, thus leading to an equivalent single input, single output (SISO system. The comparison of the resulting system with the classical first order systems typically utilized to model hydraulic canals shows that the proposed model has significantly lower error: about 50%, and, therefore, higher accuracy in capturing the canal dynamics. This model has also been utilized to optimize the design of the controller of the pump of the canal, thus achieving a faster response to step commands and thus minimizing the interaction between the two pools of the experimental platform.
Electronic circuits modeling using artificial neural networks
Directory of Open Access Journals (Sweden)
Andrejević Miona V.
2003-01-01
Full Text Available In this paper artificial neural networks (ANN are applied to modeling of electronic circuits. ANNs are used for application of the black-box modeling concept in the time domain. Modeling process is described, so the topology of the ANN, the testing signal used for excitation, together with the complexity of ANN are considered. The procedure is first exemplified in modeling of resistive circuits. MOS transistor, as a four-terminal device, is modeled. Then nonlinear negative resistive characteristic is modeled in order to be used as a piece-wise linear resistor in Chua's circuit. Examples of modeling nonlinear dynamic circuits are given encompassing a variety of modeling problems. A nonlinear circuit containing quartz oscillator is considered for modeling. Verification of the concept is performed by verifying the ability of the model to generalize i.e. to create acceptable responses to excitations not used during training. Implementation of these models within a behavioral simulator is exemplified. Every model is implemented in realistic surrounding in order to show its interaction, and of course, its usage and purpose.
Weissbrodt, David G; Holliger, Christof; Morgenroth, Eberhard
2017-03-21
New-generation bioprocesses using granular sludge aim for a high-rate removal of nutrients from wastewater with low footprint. Achieving enhanced biological phosphorus removal (EBPR) relies on the design of sludge beds and wastewater feeding conditions to optimally load the biomass and to select for polyphosphate- (PAOs) over glycogen-accumulating organisms (GAOs) and other heterotrophs. A hydraulic-metabolic mathematical model was developed to elucidate the impact of hydraulic transport patterns and environmental conditions on the PAO/GAO competition during up-flow feeding through an EBPR granular sludge bed. Tracer experiments highlighted plug-flow regimes with dispersion under both rapid (9 m h(-1) , Rebed = 1.6, Pez = 7.2, Pet = 4.6) and slow (0.9 m h(-1) , Rebed = 0.2, Pez = 21.3, Pet = 3.4) feeding. Non-turbulent regimes (Rebed Feeding time, pH, and temperature significantly impacted bacterial competition for carbon uptake under anaerobic slow feeding. Feeding duration should be designed to avoid full depletion of intracellular storage polymers within static granules. PAOs bear twice longer feeding than GAOs by using both polyphosphate and glycogen hydrolysis to sustain anaerobic C-uptake. Alkaline conditions (pH 7.25-8.0) by, e.g., dosing lime in the feed select for PAOs independently of temperature (10 - 30°C). A twice higher bed is required for full anaerobic conversions at 10 rather than 20 °C. Biosystem responses for anaerobic C-uptake can be anticipated using the model toward designing robust anaerobic selectors to manage the microbial resource in EBPR granular sludge. This article is protected by copyright. All rights reserved.
Cacace, Mauro; Jacquey, Antoine B.
2017-09-01
Theory and numerical implementation describing groundwater flow and the transport of heat and solute mass in fully saturated fractured rocks with elasto-plastic mechanical feedbacks are developed. In our formulation, fractures are considered as being of lower dimension than the hosting deformable porous rock and we consider their hydraulic and mechanical apertures as scaling parameters to ensure continuous exchange of fluid mass and energy within the fracture-solid matrix system. The coupled system of equations is implemented in a new simulator code that makes use of a Galerkin finite-element technique. The code builds on a flexible, object-oriented numerical framework (MOOSE, Multiphysics Object Oriented Simulation Environment) which provides an extensive scalable parallel and implicit coupling to solve for the multiphysics problem. The governing equations of groundwater flow, heat and mass transport, and rock deformation are solved in a weak sense (either by classical Newton-Raphson or by free Jacobian inexact Newton-Krylow schemes) on an underlying unstructured mesh. Nonlinear feedbacks among the active processes are enforced by considering evolving fluid and rock properties depending on the thermo-hydro-mechanical state of the system and the local structure, i.e. degree of connectivity, of the fracture system. A suite of applications is presented to illustrate the flexibility and capability of the new simulator to address problems of increasing complexity and occurring at different spatial (from centimetres to tens of kilometres) and temporal scales (from minutes to hundreds of years).
Land-use effects on flood generation – considering soil hydraulic measurements in modelling
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A. Münch
2009-08-01
Full Text Available The investigation in the catchment of the Mulde (51°0'55" N, 13°15'54" E Saxony, Germany researches the effect of afforestation measures on the soil hydraulic properties. The concept of a "false chronosequence" was used to quantify the time-dependent dynamical character of the forest impact. Four adjacent plots were identified at a test location with comparable pedological start conditions and a set of tree stands of different age: (1 arable field (initial state; (2 6-year-old afforestation; (3 50-year-old afforestation; (4 ancient natural forest ("target" stocking. Water retention curves and unsaturated conductivities were analysed in the lab. In the field, the undisturbed infiltration capacities were measured quantitatively (hood infiltrometer and qualitatively (brilliant blue tracer. Pronounced differences between all 4 plots were detected. The afforestation causes an increased infiltration and soil water retention potential. Especially the topsoil layers showed a distinct increase in conductivity and portion of coarse/middle pores. The influence of these changes on rainfall-runoff calculations at the test location was analysed in this study.
Parameter Identification on Lumped Parameters of the Hydraulic Engine Mount Model
Directory of Open Access Journals (Sweden)
Li Qian
2016-01-01
Full Text Available Hydraulic Engine Mounts (HEM are important vibration isolation components with compound structure in the vehicle powertrain mounting system. They have the characteristic that large damping and high dynamic stiffness in the high frequency region, and small damping and low dynamic stiffness in the low frequency region, which can meet the requirements of the vehicle powertrain mounting system better. The method to identify the lumped parameters of the HEM is not only the necessary work for the analysis and calculation in dynamic performance and can also provide the theory for the performance optimization and structure optimization of product in the future. The parameter identification method based on coupled fluid-structure interaction (FSI and finite element analysis (FEA was established in this study to identify the equivalent piston area of the rubber spring, the volume stiffness of the upper chamber, as well as the inertia coefficient and damping coefficient of the liquid through the inertia track. The simulated dynamic characteristic curves of the HEM with the parameters identified are in accordance with the measured dynamic characteristic curves well.
基于使用功能的双保险液压回路%New Model of Hydraulic Circuit Control of Double Insurance Based on Use Function
Institute of Scientific and Technical Information of China (English)
向思遇
2014-01-01
Taking the hydraulic control of the gas butterfly valve as an example and based on existing various defects and poten-tial risks of traditional hydraulic control loops,an optimized and innovative design combining three functions of continuous oil supply, standby of double insurance and automatic switch-over,was proposed. A new hydraulic circuit model with double insurance based on operational functions was built up. The functions,structural characteristics and working principles of this hydraulic circuit were ana-lyzed in order to solve the functional defects of traditional hydraulic control loops and avoid the potential accidents arising.%以煤气蝶阀的液压控制为例，针对传统液压回路所存在的各种隐患和缺陷，提出了持续给油供压、双保险备用和自动切换三大功能的有机统一，结合优化创新理念，构建一种基于使用功能的新型双保险液压回路模型，解析了该回路功能、结构特点和工作原理，解决了传统油路控制的功能缺陷和安全事故隐患。
Evaluation of Linear and Non-Linear Control Schemes Applied to a Hydraulic Servo System
DEFF Research Database (Denmark)
Andersen, Torben Ole; Hansen, Michael Rygaard; Pedersen, Henrik Clemmensen
2005-01-01
Due to the innovation of low-cost electronics such as sensors, microcontrollers etc., the focus on highperformance motion control is increasing. This work focuses on position control of single-input single-output hydraulic servo-systems in general. A hydraulically actuated robotic manipulator...... is used as test facility acting as load for the hydraulic servo system. An experimentally verified non-linear model of the complete system has been developed and used to design a series of both linear and non-linear control schemes. The controllers from each category are compared with respect to design...
Power electronics system modeling and simulation
Energy Technology Data Exchange (ETDEWEB)
Lai, Jih-Sheng
1994-12-31
This paper introduces control system design based softwares, SIMNON and MATLAB/SIMULINK, for power electronics system simulation. A complete power electronics system typically consists of a rectifier bridge along with its smoothing capacitor, an inverter, and a motor. The system components, featuring discrete or continuous, linear or nonlinear, are modeled in mathematical equations. Inverter control methods,such as pulse-width-modulation and hysteresis current control, are expressed in either computer algorithms or digital circuits. After describing component models and control methods, computer programs are then developed for complete systems simulation. Simulation results are mainly used for studying system performances, such as input and output current harmonics, torque ripples, and speed responses. Key computer programs and simulation results are demonstrated for educational purposes.
Modelling the inelastic scattering of fast electrons
Energy Technology Data Exchange (ETDEWEB)
Allen, L.J., E-mail: lja@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); D' Alfonso, A.J., E-mail: a.j@dalfonso.com.au [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Findlay, S.D. [School of Physics, Monash University, Clayton, Victoria 3800 (Australia)
2015-04-15
Imaging at atomic resolution based on the inelastic scattering of electrons has become firmly established in the last three decades. Harald Rose pioneered much of the early theoretical work on this topic, in particular emphasising the role of phase and the importance of a mixed dynamic form factor. In this paper we review how the modelling of inelastic scattering has subsequently developed and how numerical implementation has been achieved. A software package μSTEM is introduced, capable of simulating various imaging modes based on inelastic scattering in both scanning and conventional transmission electron microscopy. - Highlights: • Harald Rose was a pioneer of important work on atomic resolution imaging using inelastic scattering. • We review how the modelling of inelastic scattering has subsequently developed and been applied. • A software package μSTEM is introduced, capable of simulating various inelastic imaging modes.
1983-06-01
CONSTRUCTION TO PREVENT SCOUR Hydraulic Model Investigation by Lyndell Z . Hales, James R. Houston S.Hydraulics Laboratory .’, ! 1- N U.S. Army Engineer...hiVeStI9.e e1(_____________________________ 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(ek) 8. CONTRACT OR GRANT NUMBER(.) Lyodlell Z . Hiles James R...us t tO geerate ’ the reIpre-senatativye stonle weight, W it it the itlet-eayt’ tsectiatte. The e-xptressioni tir this- ctiese-rvi v- stabiltity
Cheviron, Bruno; Moussa, Roger
2016-09-01
This review paper investigates the determinants of modelling choices, for numerous applications of 1-D free-surface flow and morphodynamic equations in hydrology and hydraulics, across multiple spatiotemporal scales. We aim to characterize each case study by its signature composed of model refinement (Navier-Stokes: NS; Reynolds-averaged Navier-Stokes: RANS; Saint-Venant: SV; or approximations to Saint-Venant: ASV), spatiotemporal scales and subscales (domain length: L from 1 cm to 1000 km; temporal scale: T from 1 s to 1 year; flow depth: H from 1 mm to 10 m; spatial step for modelling: δL; temporal step: δT), flow typology (Overland: O; High gradient: Hg; Bedforms: B; Fluvial: F), and dimensionless numbers (dimensionless time period T*, Reynolds number Re, Froude number Fr, slope S, inundation ratio Λz, Shields number θ). The determinants of modelling choices are therefore sought in the interplay between flow characteristics and cross-scale and scale-independent views. The influence of spatiotemporal scales on modelling choices is first quantified through the expected correlation between increasing scales and decreasing model refinements (though modelling objectives also show through the chosen spatial and temporal subscales). Then flow typology appears a secondary but important determinant in the choice of model refinement. This finding is confirmed by the discriminating values of several dimensionless numbers, which prove preferential associations between model refinements and flow typologies. This review is intended to help modellers in positioning their choices with respect to the most frequent practices, within a generic, normative procedure possibly enriched by the community for a larger, comprehensive and updated image of modelling strategies.
Directory of Open Access Journals (Sweden)
A. Rais
2015-01-01
Full Text Available In order to analyze the steady state and transient behavior of the CROCUS reactor, several methods and models need to be developed in the areas of reactor physics, thermal-hydraulics, and multiphysics coupling. The long-term objectives of this project are to work towards the development of a modern method for the safety analysis of research reactors and to update the Final Safety Analysis Report of the CROCUS reactor. A first part of the paper deals with generation of a core simulator nuclear data library for the CROCUS reactor using the Serpent 2 Monte Carlo code and also with reactor core modeling using the PARCS code. PARCS eigenvalue, radial power distribution, and control rod reactivity worth results were benchmarked against Serpent 2 full-core model results. Using the Serpent 2 model as reference, PARCS eigenvalue predictions were within 240 pcm, radial power was within 3% in the central region of the core, and control rod reactivity worth was within 2%. A second part reviews the current methodology used for the safety analysis of the CROCUS reactor and presents the envisioned approach for the multiphysics modeling of the reactor.
Morbidelli, Renato; Corradini, Corrado; Govindaraju, Rao S.
2006-04-01
This study first explores the role of spatial heterogeneity, in both the saturated hydraulic conductivity Ks and rainfall intensity r, on the integrated hydrological response of a natural slope. On this basis, a mathematical model for estimating the expected areal-average infiltration is then formulated. Both Ks and r are considered as random variables with assessed probability density functions. The model relies upon a semi-analytical component, which describes the directly infiltrated rainfall, and an empirical component, which accounts further for the infiltration of surface water running downslope into pervious soils (the run-on effect). Monte Carlo simulations over a clay loam soil and a sandy loam soil were performed for constructing the ensemble averages of field-scale infiltration used for model validation. The model produced very accurate estimates of the expected field-scale infiltration rate, as well as of the outflow generated by significant rainfall events. Furthermore, the two model components were found to interact appropriately for different weights of the two infiltration mechanisms involved.
Energy Technology Data Exchange (ETDEWEB)
J. Chapman; A. Hassan; K. Pohlmann
2001-10-18
Groundwater models of seawater intrusion environments can be calibrated using both hydraulic and chemical information. The possible impact of the long-term transient process of sea level change is difficult to identify, but important to accurate simulation of present conditions. The response times of the pressure and chemical fields to major fluctuations in sea level change are investigated
Hydraulic analysis of water supply networks and controlling the leak using WATER GEMS model
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Mahmood Motevalizadeh
2016-03-01
Full Text Available Given that the discussion on water is strategic in terms of economic and social aspects as well as environmental impact, water leak in urban water-supply systems is very important, so, dealing with it is necessary and inevitable. Controlling and reducing water leak are of the main goals of water supplier organization due to limitations in terms of water resources, especially in dry lands which have few water resources. Pressure management is an efficient tool to reduce costs, enhance the operation of the network and therefore, it reduces the leak and increases the life of facilities and equipment and reduces the number of accidents. Smart pressure containment is a good way to prevent excess pressure in network to control undesirable phenomenon of leak which is directly related to pressure. In this study, Badamuiyeh water supply complex in Kerman City was selected to study on adjusting the pressure to control the leak of water and the hydraulic analysis was performed with demand-based method (DDSM, which is common technique and demand is constant, by Water GEMS software. For this end, the pressure reducing valves (prv were installed in critical point and they were timed to provide standard pressure in all nodes of the network and then, the impact of smart pressure management on water supply system has been investigated. Then its impact on the leak was examined and the results show that smart pressure control through pressure-reducing valve is a proper method for optimal management of water and reducing the leak significantly that with 45.15% reduction in average pressure, one can reduce the leak as much as 25.67% that as its result, 15380 m3 of water is annually saved in this region which is equal to 27.18% of consuming water.
Llopis-Albert, C.; Capilla, J. E.
2010-09-01
SummaryMajor factors affecting groundwater flow through fractured rocks include the geometry of each fracture, its properties and the fracture-network connectivity together with the porosity and conductivity of the rock matrix. When modelling fractured rocks this is translated into attaining a characterization of the hydraulic conductivity ( K) as adequately as possible, despite its high heterogeneity. This links with the main goal of this paper, which is to present an improvement of a stochastic inverse model, named as Gradual Conditioning (GC) method, to better characterise K in a fractured rock medium by considering different K stochastic structures, belonging to independent K statistical populations (SP) of fracture families and the rock matrix, each one with its own statistical properties. The new methodology is carried out by applying independent deformations to each SP during the conditioning process for constraining stochastic simulations to data. This allows that the statistical properties of each SPs tend to be preserved during the iterative optimization process. It is worthwhile mentioning that so far, no other stochastic inverse modelling technique, with the whole capabilities implemented in the GC method, is able to work with a domain covered by several different stochastic structures taking into account the independence of different populations. The GC method is based on a procedure that gradually changes an initial K field, which is conditioned only to K data, to approximate the reproduction of other types of information, i.e., piezometric head and solute concentration data. The approach is applied to the Äspö Hard Rock Laboratory (HRL) in Sweden, where, since the middle nineties, many experiments have been carried out to increase confidence in alternative radionuclide transport modelling approaches. Because the description of fracture locations and the distribution of hydrodynamic parameters within them are not accurate enough, we address the
Wang, Yunquan; Ma, Jinzhu; Guan, Huade; Zhu, Gaofeng
2017-06-01
Difficulty in measuring hydraulic conductivity, particularly under dry conditions, calls for methods of predicting the conductivity from easily obtained soil properties. As a complement to the recently published EMFX model, a method based on two specific suction conditions is proposed to estimate saturated film conductivity from the soil water retention curve. This method reduces one fitting parameter in the previous EMFX model, making it possible to predict the hydraulic conductivity from the soil water retention curve over the complete moisture range. Model performance is evaluated with published data of soils in a broad texture range from sand to clay. The testing results indicate that 1) the modified EMFX model (namely the EMFX-K model), incorp