Computational Fluid Dynamics and Building Energy Performance Simulation
DEFF Research Database (Denmark)
Nielsen, Peter V.; Tryggvason, Tryggvi
An interconnection between a building energy performance simulation program and a Computational Fluid Dynamics program (CFD) for room air distribution will be introduced for improvement of the predictions of both the energy consumption and the indoor environment. The building energy performance...
High-Performance Java Codes for Computational Fluid Dynamics
Riley, Christopher; Chatterjee, Siddhartha; Biswas, Rupak; Biegel, Bryan (Technical Monitor)
2001-01-01
The computational science community is reluctant to write large-scale computationally -intensive applications in Java due to concerns over Java's poor performance, despite the claimed software engineering advantages of its object-oriented features. Naive Java implementations of numerical algorithms can perform poorly compared to corresponding Fortran or C implementations. To achieve high performance, Java applications must be designed with good performance as a primary goal. This paper presents the object-oriented design and implementation of two real-world applications from the field of Computational Fluid Dynamics (CFD): a finite-volume fluid flow solver (LAURA, from NASA Langley Research Center), and an unstructured mesh adaptation algorithm (2D_TAG, from NASA Ames Research Center). This work builds on our previous experience with the design of high-performance numerical libraries in Java. We examine the performance of the applications using the currently available Java infrastructure and show that the Java version of the flow solver LAURA performs almost within a factor of 2 of the original procedural version. Our Java version of the mesh adaptation algorithm 2D_TAG performs within a factor of 1.5 of its original procedural version on certain platforms. Our results demonstrate that object-oriented software design principles are not necessarily inimical to high performance.
Computational Fluid Dynamics and Building Energy Performance Simulation
DEFF Research Database (Denmark)
Nielsen, Peter Vilhelm; Tryggvason, T.
1998-01-01
An interconnection between a building energy performance simulation program and a Computational Fluid Dynamics program (CFD) for room air distribution will be introduced for improvement of the predictions of both the energy consumption and the indoor environment. The building energy performance...... simulation program requires a detailed description of the energy flow in the air movement which can be obtained by a CFD program. The paper describes an energy consumption calculation in a large building, where the building energy simulation program is modified by CFD predictions of the flow between three...... zones connected by open areas with pressure and buoyancy driven air flow. The two programs are interconnected in an iterative procedure. The paper shows also an evaluation of the air quality in the main area of the buildings based on CFD predictions. It is shown that an interconnection between a CFD...
National Research Council Canada - National Science Library
Hisley, Dixie
1999-01-01
.... The goals of this report are: (1) to investigate the performance of message passing and loop level parallelization techniques, as they were implemented in the computational fluid dynamics (CFD...
National Research Council Canada - National Science Library
Edge, Harris
1999-01-01
...), computational fluid dynamics (CFD) 6 project. Under the project, a proven zonal Navier-Stokes solver was rewritten for scalable parallel performance on both shared memory and distributed memory high performance computers...
Comparison of two methods to determine fan performance curves using computational fluid dynamics
Onma, Patinya; Chantrasmi, Tonkid
2018-01-01
This work investigates a systematic numerical approach that employs Computational Fluid Dynamics (CFD) to obtain performance curves of a backward-curved centrifugal fan. Generating the performance curves requires a number of three-dimensional simulations with varying system loads at a fixed rotational speed. Two methods were used and their results compared to experimental data. The first method incrementally changes the mass flow late through the inlet boundary condition while the second method utilizes a series of meshes representing the physical damper blade at various angles. The generated performance curves from both methods are compared with an experiment setup in accordance with the AMCA fan performance testing standard.
Interactive Data Exploration for High-Performance Fluid Flow Computations through Porous Media
Perovic, Nevena
2014-09-01
© 2014 IEEE. Huge data advent in high-performance computing (HPC) applications such as fluid flow simulations usually hinders the interactive processing and exploration of simulation results. Such an interactive data exploration not only allows scientiest to \\'play\\' with their data but also to visualise huge (distributed) data sets in both an efficient and easy way. Therefore, we propose an HPC data exploration service based on a sliding window concept, that enables researches to access remote data (available on a supercomputer or cluster) during simulation runtime without exceeding any bandwidth limitations between the HPC back-end and the user front-end.
International Nuclear Information System (INIS)
Myeong, Hyeon Guk
1999-06-01
This book deals with computational fluid dynamics with basic and history of numerical fluid dynamics, introduction of finite volume method using one-dimensional heat conduction equation, solution of two-dimensional heat conduction equation, solution of Navier-Stokes equation, fluid with heat transport, turbulent flow and turbulent model, Navier-Stokes solution by generalized coordinate system such as coordinate conversion, conversion of basic equation, program and example of calculation, application of abnormal problem and high speed solution of numerical fluid dynamics.
High-performance computational fluid dynamics: a custom-code approach
International Nuclear Information System (INIS)
Fannon, James; Náraigh, Lennon Ó; Loiseau, Jean-Christophe; Valluri, Prashant; Bethune, Iain
2016-01-01
We introduce a modified and simplified version of the pre-existing fully parallelized three-dimensional Navier–Stokes flow solver known as TPLS. We demonstrate how the simplified version can be used as a pedagogical tool for the study of computational fluid dynamics (CFDs) and parallel computing. TPLS is at its heart a two-phase flow solver, and uses calls to a range of external libraries to accelerate its performance. However, in the present context we narrow the focus of the study to basic hydrodynamics and parallel computing techniques, and the code is therefore simplified and modified to simulate pressure-driven single-phase flow in a channel, using only relatively simple Fortran 90 code with MPI parallelization, but no calls to any other external libraries. The modified code is analysed in order to both validate its accuracy and investigate its scalability up to 1000 CPU cores. Simulations are performed for several benchmark cases in pressure-driven channel flow, including a turbulent simulation, wherein the turbulence is incorporated via the large-eddy simulation technique. The work may be of use to advanced undergraduate and graduate students as an introductory study in CFDs, while also providing insight for those interested in more general aspects of high-performance computing. (paper)
High-performance computational fluid dynamics: a custom-code approach
Fannon, James; Loiseau, Jean-Christophe; Valluri, Prashant; Bethune, Iain; Náraigh, Lennon Ó.
2016-07-01
We introduce a modified and simplified version of the pre-existing fully parallelized three-dimensional Navier-Stokes flow solver known as TPLS. We demonstrate how the simplified version can be used as a pedagogical tool for the study of computational fluid dynamics (CFDs) and parallel computing. TPLS is at its heart a two-phase flow solver, and uses calls to a range of external libraries to accelerate its performance. However, in the present context we narrow the focus of the study to basic hydrodynamics and parallel computing techniques, and the code is therefore simplified and modified to simulate pressure-driven single-phase flow in a channel, using only relatively simple Fortran 90 code with MPI parallelization, but no calls to any other external libraries. The modified code is analysed in order to both validate its accuracy and investigate its scalability up to 1000 CPU cores. Simulations are performed for several benchmark cases in pressure-driven channel flow, including a turbulent simulation, wherein the turbulence is incorporated via the large-eddy simulation technique. The work may be of use to advanced undergraduate and graduate students as an introductory study in CFDs, while also providing insight for those interested in more general aspects of high-performance computing.
Directory of Open Access Journals (Sweden)
Shankhadeep Das
2016-01-01
Full Text Available Sedimentation is one of the most popular wastewater treatment processes, and is used to separate solid particles from carrier fluid in settling tanks known as clarifiers. The clarifier, as the last major facility in wastewater treatment plants (WWTPs, can limit or define the performance of the overall WWTP. This paper presents a novel three-dimensional unsteady computational fluid dynamics (CFD model to improve the efficiency of an industrial clarifier that had been experiencing underperformance and reduction in wastewater handling capacity. We propose a numerical technique to address the transient process of removing sludge from the floor of clarifiers by using rotating rakes. The CFD model was first applied to analyzing the ramifications of the current clarifier geometry on performance. The results show that the root causes for underperformance are related to the unconventional top side feed design of the clarifier, which leads to significant asymmetry in the flow distribution. The CFD model was next used to investigate various design modifications with the goal of improving the clarifier performance. A few geometry modification ideas such as an inward baffle, dissipating inlets, and a submerged skirt were found to create a more uniform flow distribution in the clarifier, significantly reducing the backflow into the feedwell and the velocity of the flow exiting the feedwell, which helps the solid particles to settle in the clarifier. These three designs were found to reduce the effluent total suspended solids (TSS by more than 80% and thus significantly improve clarifier performance. It is believed that the CFD model developed in this study can become a computationally efficient tool for investigating the performance of industrial clarifiers with complex geometries and rotating rakes.
Unit physics performance of a mix model in Eulerian fluid computations
Energy Technology Data Exchange (ETDEWEB)
Vold, Erik [Los Alamos National Laboratory; Douglass, Rod [Los Alamos National Laboratory
2011-01-25
In this report, we evaluate the performance of a K-L drag-buoyancy mix model, described in a reference study by Dimonte-Tipton [1] hereafter denoted as [D-T]. The model was implemented in an Eulerian multi-material AMR code, and the results are discussed here for a series of unit physics tests. The tests were chosen to calibrate the model coefficients against empirical data, principally from RT (Rayleigh-Taylor) and RM (Richtmyer-Meshkov) experiments, and the present results are compared to experiments and to results reported in [D-T]. Results show the Eulerian implementation of the mix model agrees well with expectations for test problems in which there is no convective flow of the mass averaged fluid, i.e., in RT mix or in the decay of homogeneous isotropic turbulence (HIT). In RM shock-driven mix, the mix layer moves through the Eulerian computational grid, and there are differences with the previous results computed in a Lagrange frame [D-T]. The differences are attributed to the mass averaged fluid motion and examined in detail. Shock and re-shock mix are not well matched simultaneously. Results are also presented and discussed regarding model sensitivity to coefficient values and to initial conditions (IC), grid convergence, and the generation of atomically mixed volume fractions.
Directory of Open Access Journals (Sweden)
Paolo Maria Congedo
2016-11-01
Full Text Available Improving energy efficiency in buildings and promoting renewables are key objectives of European energy policies. Several technological measures are being developed to enhance the energy performance of buildings. Among these, geothermal systems present a huge potential to reduce energy consumption for mechanical ventilation and cooling, but their behavior depending on varying parameters, boundary and climatic conditions is not fully established. In this paper a horizontal air-ground heat exchanger (HAGHE system is studied by the development of a computational fluid dynamics (CFD model. Summer and winter conditions representative of the Mediterranean climate are analyzed to evaluate operation and thermal performance differences. A particular focus is given to humidity variations as this parameter has a major impact on indoor air quality and comfort. Results show the benefits that HAGHE systems can provide in reducing energy consumption in all seasons, in summer when free-cooling can be implemented avoiding post air treatment using heat pumps.
International Nuclear Information System (INIS)
Duan, Shengbing; Ni, Weijia; Luo, Hongzhen; Shi, Zhongping; Liu, Fan; Yuan, Guoqiang; Zhao, Yanli
2013-01-01
Cephalosporin C (CPC) fermentation by Acremonium chrysogenum is an extremely high oxygen-consuming process and oxygen transfer rate in a bioreactor directly affects fermentation performance. In this study, fluid dynamics and oxygen transfer in a 7 L bioreactor with different impellers combinations were simulated by computational fluid dynamics (CFD) model. Based on the simulation results, two impeller combinations with higher oxygen transfer rate (K_La) were selected to conduct CPC fermentations, aiming at achieving high CPC concentration and low accumulation of major by-product, deacetoxycephalosporin (DAOC). It was found that an impeller combination with a higher K_La and moderate shear force is the prerequisite for efficient CPC production in a stirred bioreactor. The best impeller combination, which installed a six-bladed turbine and a four-pitched-blade turbine at bottom and upper layers but with a shortened impellers inter-distance, produced the highest CPC concentration of 35.77 g/L and lowest DAOC/CPC ratio of 0.5%
Energy Technology Data Exchange (ETDEWEB)
Duan, Shengbing; Ni, Weijia; Luo, Hongzhen; Shi, Zhongping; Liu, Fan [Jiangnan University, Wuxi (China); Yuan, Guoqiang; Zhao, Yanli [CSPC Hebei Zhongrun Pharmaceutical Co. Ltd., Shijiazhuang (China)
2013-05-15
Cephalosporin C (CPC) fermentation by Acremonium chrysogenum is an extremely high oxygen-consuming process and oxygen transfer rate in a bioreactor directly affects fermentation performance. In this study, fluid dynamics and oxygen transfer in a 7 L bioreactor with different impellers combinations were simulated by computational fluid dynamics (CFD) model. Based on the simulation results, two impeller combinations with higher oxygen transfer rate (K{sub L}a) were selected to conduct CPC fermentations, aiming at achieving high CPC concentration and low accumulation of major by-product, deacetoxycephalosporin (DAOC). It was found that an impeller combination with a higher K{sub L}a and moderate shear force is the prerequisite for efficient CPC production in a stirred bioreactor. The best impeller combination, which installed a six-bladed turbine and a four-pitched-blade turbine at bottom and upper layers but with a shortened impellers inter-distance, produced the highest CPC concentration of 35.77 g/L and lowest DAOC/CPC ratio of 0.5%.
Computational fluid dynamic applications
Energy Technology Data Exchange (ETDEWEB)
Chang, S.-L.; Lottes, S. A.; Zhou, C. Q.
2000-04-03
The rapid advancement of computational capability including speed and memory size has prompted the wide use of computational fluid dynamics (CFD) codes to simulate complex flow systems. CFD simulations are used to study the operating problems encountered in system, to evaluate the impacts of operation/design parameters on the performance of a system, and to investigate novel design concepts. CFD codes are generally developed based on the conservation laws of mass, momentum, and energy that govern the characteristics of a flow. The governing equations are simplified and discretized for a selected computational grid system. Numerical methods are selected to simplify and calculate approximate flow properties. For turbulent, reacting, and multiphase flow systems the complex processes relating to these aspects of the flow, i.e., turbulent diffusion, combustion kinetics, interfacial drag and heat and mass transfer, etc., are described in mathematical models, based on a combination of fundamental physics and empirical data, that are incorporated into the code. CFD simulation has been applied to a large variety of practical and industrial scale flow systems.
International Nuclear Information System (INIS)
Smith, B.L.
2011-01-01
Such a target forms part of the evolutionary Accelerator-Driven System (ADS) concept in which neutrons are generated in an otherwise sub-critical core by spallation reactions resulting from bombardment by a proton beam. The international project MEGAPIE had the objective of demonstrating the feasibility of the spallation process for a particular target design under strict test conditions. The test was carried over a period of four months at the end of 2006 at the SINQ facility of the Paul Scherrer Institute in Switzerland. The design studies carried out for the MEGAPIE target prior to irradiation using Computational Fluid Dynamics (CFD) resulted in an optimum flow configuration being defined for the coolant circulation. Simultaneously, stresses in the structural components were examined using Finite Element Method (FEM) techniques. To this purpose, an interface program was written which enabled different specialist groups to carry out the thermal hydraulics and structural mechanics analyses within the project with fully consistent model data. Results for steady-state operation of the target show that the critical lower target components are adequately cooled, and that stresses and displacements are well within tolerances. Transient analyses were also performed to demonstrate the robustness of the design in the event of abnormal operation, including pump failure and burn-through of the target casing by the proton beam. In the latter case, the CFD analyses complemented and extended full-scale tests. (author)
Energy Technology Data Exchange (ETDEWEB)
Smith, B.L., E-mail: brian.smith@psi.ch [Paul Scherrer Institute, OHSA/C08, 5232 Villigen PSI (Switzerland)
2011-07-01
Such a target forms part of the evolutionary Accelerator-Driven System (ADS) concept in which neutrons are generated in an otherwise sub-critical core by spallation reactions resulting from bombardment by a proton beam. The international project MEGAPIE had the objective of demonstrating the feasibility of the spallation process for a particular target design under strict test conditions. The test was carried over a period of four months at the end of 2006 at the SINQ facility of the Paul Scherrer Institute in Switzerland. The design studies carried out for the MEGAPIE target prior to irradiation using Computational Fluid Dynamics (CFD) resulted in an optimum flow configuration being defined for the coolant circulation. Simultaneously, stresses in the structural components were examined using Finite Element Method (FEM) techniques. To this purpose, an interface program was written which enabled different specialist groups to carry out the thermal hydraulics and structural mechanics analyses within the project with fully consistent model data. Results for steady-state operation of the target show that the critical lower target components are adequately cooled, and that stresses and displacements are well within tolerances. Transient analyses were also performed to demonstrate the robustness of the design in the event of abnormal operation, including pump failure and burn-through of the target casing by the proton beam. In the latter case, the CFD analyses complemented and extended full-scale tests. (author)
DEFF Research Database (Denmark)
Nielsen, Peter Vilhelm
2003-01-01
An interconnection between a building energy performance simulation program and a Computational Fluid Dynamics program (CFD) for room air distribution is introduced for improvement of the predictions of both the energy consumption and the indoor environment.The article describes a calculation...
de Boer, Anne H.; Hagedoorn, Paul; Woolhouse, Robert; Wynn, Ed
Objectives To use computational fluid dynamics (CFD) for evaluating and understanding the performance of the high-dose disposable Twincer (TM) dry powder inhaler, as well as to learn the effect of design modifications on dose entrainment, powder dispersion and retention behaviour. Methods Comparison
Holden, Jacob R.
Descending maple seeds generate lift to slow their fall and remain aloft in a blowing wind; have the wings of these seeds evolved to descend as slowly as possible? A unique energy balance equation, experimental data, and computational fluid dynamics simulations have all been developed to explore this question from a turbomachinery perspective. The computational fluid dynamics in this work is the first to be performed in the relative reference frame. Maple seed performance has been analyzed for the first time based on principles of wind turbine analysis. Application of the Betz Limit and one-dimensional momentum theory allowed for empirical and computational power and thrust coefficients to be computed for maple seeds. It has been determined that the investigated species of maple seeds perform near the Betz limit for power conversion and thrust coefficient. The power coefficient for a maple seed is found to be in the range of 48-54% and the thrust coefficient in the range of 66-84%. From Betz theory, the stream tube area expansion of the maple seed is necessary for power extraction. Further investigation of computational solutions and mechanical analysis find three key reasons for high maple seed performance. First, the area expansion is driven by maple seed lift generation changing the fluid momentum and requiring area to increase. Second, radial flow along the seed surface is promoted by a sustained leading edge vortex that centrifuges low momentum fluid outward. Finally, the area expansion is also driven by the spanwise area variation of the maple seed imparting a radial force on the flow. These mechanisms result in a highly effective device for the purpose of seed dispersal. However, the maple seed also provides insight into fundamental questions about how turbines can most effectively change the momentum of moving fluids in order to extract useful power or dissipate kinetic energy.
Essential Computational Fluid Dynamics
Zikanov, Oleg
2011-01-01
This book serves as a complete and self-contained introduction to the principles of Computational Fluid Dynamic (CFD) analysis. It is deliberately short (at approximately 300 pages) and can be used as a text for the first part of the course of applied CFD followed by a software tutorial. The main objectives of this non-traditional format are: 1) To introduce and explain, using simple examples where possible, the principles and methods of CFD analysis and to demystify the `black box’ of a CFD software tool, and 2) To provide a basic understanding of how CFD problems are set and
Directory of Open Access Journals (Sweden)
W. P. Martignoni
2007-03-01
Full Text Available Cyclone models have been used without relevant modifications for more than a century. Most of the attention has been focused on finding new methods to improve performance parameters. Recently, some studies were conducted to improve equipment performance by evaluating geometric effects on projects. In this work, the effect of cyclone geometry was studied through the creation of a symmetrical inlet and a volute scroll outlet section in an experimental cyclone and comparison to an ordinary single tangential inlet. The study was performed for gas-solid flow, based on an experimental study available in the literature, where a conventional cyclone model was used. Numerical experiments were performed by using CFX 5.7.1. The axial and tangential velocity components were evaluated using RSM and LES turbulence models. Results showed that these new designs can improve the cyclone performance parameters significantly and very interesting details were found on cyclone fluid dynamics properties using RSM and LES.
Fluid simulation for computer graphics
Bridson, Robert
2008-01-01
Animating fluids like water, smoke, and fire using physics-based simulation is increasingly important in visual effects, in particular in movies, like The Day After Tomorrow, and in computer games. This book provides a practical introduction to fluid simulation for graphics. The focus is on animating fully three-dimensional incompressible flow, from understanding the math and the algorithms to the actual implementation.
Hassan, H. A.
1993-01-01
Two papers are included in this progress report. In the first, the compressible Navier-Stokes equations have been used to compute leading edge receptivity of boundary layers over parabolic cylinders. Natural receptivity at the leading edge was simulated and Tollmien-Schlichting waves were observed to develop in response to an acoustic disturbance, applied through the farfield boundary conditions. To facilitate comparison with previous work, all computations were carried out at a free stream Mach number of 0.3. The spatial and temporal behavior of the flowfields are calculated through the use of finite volume algorithms and Runge-Kutta integration. The results are dominated by strong decay of the Tollmien-Schlichting wave due to the presence of the mean flow favorable pressure gradient. The effects of numerical dissipation, forcing frequency, and nose radius are studied. The Strouhal number is shown to have the greatest effect on the unsteady results. In the second paper, a transition model for low-speed flows, previously developed by Young et al., which incorporates first-mode (Tollmien-Schlichting) disturbance information from linear stability theory has been extended to high-speed flow by incorporating the effects of second mode disturbances. The transition model is incorporated into a Reynolds-averaged Navier-Stokes solver with a one-equation turbulence model. Results using a variable turbulent Prandtl number approach demonstrate that the current model accurately reproduces available experimental data for first and second-mode dominated transitional flows. The performance of the present model shows significant improvement over previous transition modeling attempts.
de Boer, Anne H; Hagedoorn, Paul; Woolhouse, Robert; Wynn, Ed
2012-09-01
To use computational fluid dynamics (CFD) for evaluating and understanding the performance of the high-dose disposable Twincer™ dry powder inhaler, as well as to learn the effect of design modifications on dose entrainment, powder dispersion and retention behaviour. Comparison of predicted flow and particle behaviour from CFD computations with experimental data obtained with cascade impactor and laser diffraction analysis. Inhaler resistance, flow split, particle trajectories and particle residence times can well be predicted with CFD for a multiple classifier based inhaler like the Twincer™. CFD computations showed that the flow split of the Twincer™ is independent of the pressure drop across the inhaler and that the total flow rate can be decreased without affecting the dispersion efficacy or retention behaviour. They also showed that classifier symmetry can be improved by reducing the resistance of one of the classifier bypass channels, which for the current concept does not contribute to the swirl in the classifier chamber. CFD is a highly valuable tool for development and optimisation of dry powder inhalers. CFD can assist adapting the inhaler design to specific physico-chemical properties of the drug formulation with respect to dispersion and retention behaviour. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.
International Nuclear Information System (INIS)
Perng, Shiang-Wuu; Horng, Rong-Fang; Wu, Horng-Wen
2017-01-01
Highlights: •We enhance performance of a cylindrical MSR to get higher net power of fuel cell. •We study diffuser angle and length and wall temperature on net power of fuel cell. •We study methanol conversion, hydrogen production, CO of a novel reformer. •Diffuser in catalyst bed upstream raises methanol conversion, hydrogen production. •The MSR raises hydrogen production up to 44.6% and net fuel cell power up to 24.6%. -- Abstract: Proton exchange membrane fuel cells (PEMFC) connected with a methanol steam reformer designed to enhance its performance is considered as a promising future power source. Enhancing the performance of a cylindrical methanol steam reformer due to diffuser effects was then investigated applying three-dimensional computational fluid dynamics by the SIMPLE-C algorithm and an Arrhenius form of reaction model. The effect of the angle and length of the diffuser, and wall temperature have been explored on heat and fluid flow, methanol conversion, hydrogen production, carbon monoxide reduction, as well as estimated net power of fuel cell with the same catalyst volume and entrance condition in a cylindrical methanol steam reformer. The results indicate that the diffuser obviously enhances methanol conversion and hydrogen production of a cylindrical methanol steam reformer. In comparison with a traditional reformer, the reformer with a diffuser of θ d = 6° and L d = 75 mm obtains the maximum enhancement of 22.96% in methanol conversion, 44.62% in hydrogen production, and 24.59% in estimated net power of fuel cell at wall temperature of 250 °C. In addition, the novel reformer with a diffuser of θ d = 9° and L d = 100 mm generates the maximum reduction of 44.17% in CO production at T W = 250 °C.
Blocken, B.J.E.; Stathopoulos, T.; Carmeliet, J.; Hensen, J.L.M.
2011-01-01
This paper provides an overview of the application of CFD in building performance simulation for the outdoor environment, focused on four topics: (1) pedestrian wind environment around buildings, (2) wind-driven rain on building facades, (3) convective heat transfer coefficients at exterior building
A Computational Fluid Dynamics Algorithm on a Massively Parallel Computer
Jespersen, Dennis C.; Levit, Creon
1989-01-01
The discipline of computational fluid dynamics is demanding ever-increasing computational power to deal with complex fluid flow problems. We investigate the performance of a finite-difference computational fluid dynamics algorithm on a massively parallel computer, the Connection Machine. Of special interest is an implicit time-stepping algorithm; to obtain maximum performance from the Connection Machine, it is necessary to use a nonstandard algorithm to solve the linear systems that arise in the implicit algorithm. We find that the Connection Machine ran achieve very high computation rates on both explicit and implicit algorithms. The performance of the Connection Machine puts it in the same class as today's most powerful conventional supercomputers.
Shen, Fei; Tian, Libin; Yuan, Hairong; Pang, Yunzhi; Chen, Shulin; Zou, Dexun; Zhu, Baoning; Liu, Yanping; Li, Xiujin
2013-10-01
As a lignocellulose-based substrate for anaerobic digestion, rice straw is characterized by low density, high water absorbability, and poor fluidity. Its mixing performances in digestion are completely different from traditional substrates such as animal manures. Computational fluid dynamics (CFD) simulation was employed to investigate mixing performances and determine suitable stirring parameters for efficient biogas production from rice straw. The results from CFD simulation were applied in the anaerobic digestion tests to further investigate their reliability. The results indicated that the mixing performances could be improved by triple impellers with pitched blade, and complete mixing was easily achieved at the stirring rate of 80 rpm, as compared to 20-60 rpm. However, mixing could not be significantly improved when the stirring rate was further increased from 80 to 160 rpm. The simulation results agreed well with the experimental results. The determined mixing parameters could achieve the highest biogas yield of 370 mL (g TS)(-1) (729 mL (g TS(digested))(-1)) and 431 mL (g TS)(-1) (632 mL (g TS(digested))(-1)) with the shortest technical digestion time (T 80) of 46 days. The results obtained in this work could provide useful guides for the design and operation of biogas plants using rice straw as substrates.
Directory of Open Access Journals (Sweden)
Emma Frosina
2017-01-01
Full Text Available Small and micro hydropower systems represent an attractive solution for generating electricity at low cost and with low environmental impact. The pump-as-turbine (PAT approach has promise in this application due to its low purchase and maintenance costs. In this paper, a new method to predict the inverse characteristic of industrial centrifugal pumps is presented. This method is based on results of simulations performed with commercial three-dimensional Computational Fluid Dynamics (CFD software. Model results have been first validated in pumping mode using data supplied by pump manufacturers. Then, the results have been compared to experimental data for a pump running in reverse. Experimentation has been performed on a dedicated test bench installed in the Department of Civil Construction and Environmental Engineering of the University of Naples Federico II. Three different pumps, with different specific speeds, have been analyzed. Using the model results, the inverse characteristic and the best efficiency point have been evaluated. Finally, results have been compared to prediction methods available in the literature.
Computational modelling in fluid mechanics
International Nuclear Information System (INIS)
Hauguel, A.
1985-01-01
The modelling of the greatest part of environmental or industrial flow problems gives very similar types of equations. The considerable increase in computing capacity over the last ten years consequently allowed numerical models of growing complexity to be processed. The varied group of computer codes presented are now a complementary tool of experimental facilities to achieve studies in the field of fluid mechanics. Several codes applied in the nuclear field (reactors, cooling towers, exchangers, plumes...) are presented among others [fr
Computational Fluid Dynamics in Ventilation
DEFF Research Database (Denmark)
Nielsen, Peter V.; Allard, Francis; Awbi, Hazim B.
2008-01-01
Computational Fluid Dynamics in Ventilation Design is a new title in the is a new title in the REHVA guidebook series. The guidebook is written for people who need to use and discuss results based on CFD predictions, and it gives insight into the subject for those who are not used to work with CFD...
Luthfie, A. A.; Pratiwi, S. E.; Hidayatulloh, P.
2018-03-01
Indonesia is a country which has abundant renewable energy resources, comprises of water, solar, geothermal, wind, bioenergy, and ocean energy. Utilization of water energy through MHP is widely applied in remote areas in Indonesia. This utilization requires a water-converting device known as a water turbine. Rosefsky (2010) developed a water turbine known as the Hydrocoil turbine. This turbine is an axial turbine which is a modification of screw turbine. This turbine has a pitch length that decreases in the direction of the water flow and is able to work at relatively low water flow and head. The use of Hydrocoil turbine has not been widely applied in Indonesia, therefore this research is focused on analyzing the performance of Hydrocoil turbine. The analysis was performed using Computational Fluid Dynamics (CFD) method. Hydrocoil turbine performance analysis was performed at 3 m, 4 m, and 5 m head respectively as well as rotational speed variations of 100 rpm, 300 rpm, 500 rpm, 700 rpm, 900 rpm, 1,100 rpm, 1,300 rpm, 1,500 rpm, 1,700 rpm, and 1,900 rpm. Based on simulation result, the largest power generated by the turbine at 3 m head is 1,134.06 W, while at 4 m and 5 m are 1,722.39 W and 2,231.49 W respectively. It is also found that the largest turbine’s efficiency at 3 m head is 93.22% while at 4 m and 5 m head are 94.6% and 89.88% respectively. The result also shows that the larger the head the greater the operational rotational speed range.
Directory of Open Access Journals (Sweden)
Sayed Ahmed Imran Bellary
2016-01-01
Full Text Available To reduce the total design and optimization time, numerical analysis with surrogate-based approaches is being used in turbomachinery optimization. In this work, multiple surrogates are coupled with an evolutionary genetic algorithm to find the Pareto optimal fronts (PoFs of two centrifugal pumps with different specifications in order to enhance their performance. The two pumps were used a centrifugal pump commonly used in industry (Case I and an electrical submersible pump used in the petroleum industry (Case II. The objectives are to enhance head and efficiency of the pumps at specific flow rates. Surrogates such as response surface approximation (RSA, Kriging (KRG, neural networks and weighted-average surrogates (WASs were used to determine the PoFs. To obtain the objective functions’ values and to understand the flow physics, Reynolds-averaged Navier–Stokes equations were solved. It is found that the WAS performs better for both the objectives than any other individual surrogate. The best individual surrogates or the best predicted error sum of squares (PRESS surrogate (BPS obtained from cross-validation (CV error estimations produced better PoFs but was still unable to compete with the WAS. The high CV error-producing surrogate produced the worst PoFs. The performance improvement in this study is due to the change in flow pattern in the passage of the impeller of the pumps.
Compressible Fluid Suspension Performance Testing
National Research Council Canada - National Science Library
Hoogterp, Francis
2003-01-01
... compressible fluid suspension system that was designed and installed on the vehicle by DTI. The purpose of the tests was to evaluate the possible performance benefits of the compressible fluid suspension system...
Chandra, Yatish
in the industry were discussed and concluded with a stress on dependency on higher fidelity methods such as Computational Fluid Dynamics.
Principles of computational fluid dynamics
Wesseling, Pieter
2001-01-01
The book is aimed at graduate students, researchers, engineers and physicists involved in flow computations. An up-to-date account is given of the present state-of-the-art of numerical methods employed in computational fluid dynamics. The underlying numerical principles are treated with a fair amount of detail, using elementary mathematical analysis. Attention is given to difficulties arising from geometric complexity of the flow domain and of nonuniform structured boundary-fitted grids. Uniform accuracy and efficiency for singular perturbation problems is studied, pointing the way to accurate computation of flows at high Reynolds number. Much attention is given to stability analysis, and useful stability conditions are provided, some of them new, for many numerical schemes used in practice. Unified methods for compressible and incompressible flows are discussed. Numerical analysis of the shallow-water equations is included. The theory of hyperbolic conservation laws is treated. Godunov's order barrier and ho...
Finite element computational fluid mechanics
International Nuclear Information System (INIS)
Baker, A.J.
1983-01-01
This book analyzes finite element theory as applied to computational fluid mechanics. It includes a chapter on using the heat conduction equation to expose the essence of finite element theory, including higher-order accuracy and convergence in a common knowledge framework. Another chapter generalizes the algorithm to extend application to the nonlinearity of the Navier-Stokes equations. Other chapters are concerned with the analysis of a specific fluids mechanics problem class, including theory and applications. Some of the topics covered include finite element theory for linear mechanics; potential flow; weighted residuals/galerkin finite element theory; inviscid and convection dominated flows; boundary layers; parabolic three-dimensional flows; and viscous and rotational flows
Computational methods for fluid dynamics
Ferziger, Joel H
2002-01-01
In its 3rd revised and extended edition the book offers an overview of the techniques used to solve problems in fluid mechanics on computers and describes in detail those most often used in practice. Included are advanced methods in computational fluid dynamics, like direct and large-eddy simulation of turbulence, multigrid methods, parallel computing, moving grids, structured, block-structured and unstructured boundary-fitted grids, free surface flows. The 3rd edition contains a new section dealing with grid quality and an extended description of discretization methods. The book shows common roots and basic principles for many different methods. The book also contains a great deal of practical advice for code developers and users, it is designed to be equally useful to beginners and experts. The issues of numerical accuracy, estimation and reduction of numerical errors are dealt with in detail, with many examples. A full-feature user-friendly demo-version of a commercial CFD software has been added, which ca...
International Nuclear Information System (INIS)
Parihar, A.; Kulkarni, A.; Stern, F.; Xing, T.; Moeykens, S.
2005-01-01
Flow over an Ahmed body is a key benchmark case for validating the complex turbulent flow field around vehicles. In spite of the simple geometry, the flow field around an Ahmed body retains critical features of real, external vehicular flow. The present study is an attempt to implement such a real life example into the course curriculum for undergraduate engineers. FlowLab, which is a Computational Fluid Dynamics (CFD) tool developed by Fluent Inc. for use in engineering education, allows students to conduct interactive application studies. This paper presents a synopsis of FlowLab, a description of one FlowLab exercise, and an overview of the educational experience gained by students through using FlowLab, which is understood through student surveys and examinations. FlowLab-based CFD exercises were implemented into 57:020 Mechanics of Fluids and Transport Processes and 58:160 Intermediate Mechanics of Fluids courses at the University of Iowa in the fall of 2004, although this report focuses only on experiences with the Ahmed body exercise, which was used only in the intermediate-level fluids class, 58:160. This exercise was developed under National Science Foundation funding by the authors of this paper. The focus of this study does not include validating the various turbulence models used for the Ahmed body simulation, because a two-dimensional simplification was applied. With the two-dimensional simplification, students may setup, run, and post process this model in a 50 minute class period using a single-CPU PC, as required for the 58:160 class at the University of Iowa. It is educational for students to understand the implication of a two- dimensional approximation for essentially a three-dimensional flow field, along with the consequent variation in both qualitative and quantitative results. Additionally, through this exercise, students may realize that the choice of the respective turbulence model will affect simulation prediction. (author)
Graphics supercomputer for computational fluid dynamics research
Liaw, Goang S.
1994-11-01
The objective of this project is to purchase a state-of-the-art graphics supercomputer to improve the Computational Fluid Dynamics (CFD) research capability at Alabama A & M University (AAMU) and to support the Air Force research projects. A cutting-edge graphics supercomputer system, Onyx VTX, from Silicon Graphics Computer Systems (SGI), was purchased and installed. Other equipment including a desktop personal computer, PC-486 DX2 with a built-in 10-BaseT Ethernet card, a 10-BaseT hub, an Apple Laser Printer Select 360, and a notebook computer from Zenith were also purchased. A reading room has been converted to a research computer lab by adding some furniture and an air conditioning unit in order to provide an appropriate working environments for researchers and the purchase equipment. All the purchased equipment were successfully installed and are fully functional. Several research projects, including two existing Air Force projects, are being performed using these facilities.
Visualization of unsteady computational fluid dynamics
Haimes, Robert
1994-11-01
A brief summary of the computer environment used for calculating three dimensional unsteady Computational Fluid Dynamic (CFD) results is presented. This environment requires a super computer as well as massively parallel processors (MPP's) and clusters of workstations acting as a single MPP (by concurrently working on the same task) provide the required computational bandwidth for CFD calculations of transient problems. The cluster of reduced instruction set computers (RISC) is a recent advent based on the low cost and high performance that workstation vendors provide. The cluster, with the proper software can act as a multiple instruction/multiple data (MIMD) machine. A new set of software tools is being designed specifically to address visualizing 3D unsteady CFD results in these environments. Three user's manuals for the parallel version of Visual3, pV3, revision 1.00 make up the bulk of this report.
Principles of computational fluid dynamics
International Nuclear Information System (INIS)
Wesseling, P.
2001-01-01
The book is aimed at graduate students, researchers, engineers and physicists involved in flow computations. An up-to-date account is given of the present state- of-the-art of numerical methods employed in computational fluid dynamics. The underlying numerical principles are treated with a fair amount of detail, using elementary mathematical analysis. Attention is given to difficulties arising from geometric complexity of the flow domain and of nonuniform structured boundary-fitted grids. Uniform accuracy and efficiency for singular perturbation problems is studied, pointing the way to accurate computation of flows at high Reynolds number. Much attention is given to stability analysis, and useful stability conditions are provided, some of them new, for many numerical schemes used in practice. Unified methods for compressible and incompressible flows are discussed. Numerical analysis of the shallow-water equations is included. The theory of hyperbolic conservation laws is treated. Godunov's order barrier and how to overcome it by means of slope-limited schemes is discussed. An introduction is given to efficient iterative solution methods, using Krylov subspace and multigrid acceleration. Many pointers are given to recent literature, to help the reader to quickly reach the current research frontier. (orig.)
Performance Testing of Cutting Fluids
DEFF Research Database (Denmark)
Belluco, Walter
The importance of cutting fluid performance testing has increased with documentation requirements of new cutting fluid formulations based on more sustainable products, as well as cutting with minimum quantity of lubrication and dry cutting. Two sub-problems have to be solved: i) which machining...... tests feature repeatability, reproducibility and sensitivity to cutting fluids, and ii) to what extent results of one test ensure relevance to a wider set of machining situations. The present work is aimed at assessing the range of validity of the different testing methods, investigating correlation...... within the whole range of operations, materials, cutting fluids, operating conditions, etc. Cutting fluid performance was evaluated in turning, drilling, reaming and tapping, and with respect to tool life, cutting forces, chip formation and product quality (dimensional accuracy and surface integrity...
Sadovskii, Vladimir; Sadovskaya, Oxana
2017-04-01
A thermodynamically consistent approach to the description of linear and nonlinear wave processes in a blocky medium, which consists of a large number of elastic blocks interacting with each other via pliant interlayers, is proposed. The mechanical properties of interlayers are defined by means of the rheological schemes of different levels of complexity. Elastic interaction between the blocks is considered in the framework of the linear elasticity theory [1]. The effects of viscoelastic shear in the interblock interlayers are taken into consideration using the Pointing-Thomson rheological scheme. The model of an elastic porous material is used in the interlayers, where the pores collapse if an abrupt compressive stress is applied. On the basis of the Biot equations for a fluid-saturated porous medium, a new mathematical model of a blocky medium is worked out, in which the interlayers provide a convective fluid motion due to the external perturbations. The collapse of pores is modeled within the generalized rheological approach, wherein the mechanical properties of a material are simulated using four rheological elements. Three of them are the traditional elastic, viscous and plastic elements, the fourth element is the so-called rigid contact [2], which is used to describe the behavior of materials with different resistance to tension and compression. Thermodynamic consistency of the equations in interlayers with the equations in blocks guarantees fulfillment of the energy conservation law for a blocky medium in a whole, i.e. kinetic and potential energy of the system is the sum of kinetic and potential energies of the blocks and interlayers. As a result of discretization of the equations of the model, robust computational algorithm is constructed, that is stable because of the thermodynamic consistency of the finite difference equations at a discrete level. The splitting method by the spatial variables and the Godunov gap decay scheme are used in the blocks, the
Using Computers in Fluids Engineering Education
Benson, Thomas J.
1998-01-01
Three approaches for using computers to improve basic fluids engineering education are presented. The use of computational fluid dynamics solutions to fundamental flow problems is discussed. The use of interactive, highly graphical software which operates on either a modern workstation or personal computer is highlighted. And finally, the development of 'textbooks' and teaching aids which are used and distributed on the World Wide Web is described. Arguments for and against this technology as applied to undergraduate education are also discussed.
Fluid dynamics theory, computation, and numerical simulation
Pozrikidis, C
2001-01-01
Fluid Dynamics Theory, Computation, and Numerical Simulation is the only available book that extends the classical field of fluid dynamics into the realm of scientific computing in a way that is both comprehensive and accessible to the beginner The theory of fluid dynamics, and the implementation of solution procedures into numerical algorithms, are discussed hand-in-hand and with reference to computer programming This book is an accessible introduction to theoretical and computational fluid dynamics (CFD), written from a modern perspective that unifies theory and numerical practice There are several additions and subject expansions in the Second Edition of Fluid Dynamics, including new Matlab and FORTRAN codes Two distinguishing features of the discourse are solution procedures and algorithms are developed immediately after problem formulations are presented, and numerical methods are introduced on a need-to-know basis and in increasing order of difficulty Matlab codes are presented and discussed for a broad...
Fluid Dynamics Theory, Computation, and Numerical Simulation
Pozrikidis, Constantine
2009-01-01
Fluid Dynamics: Theory, Computation, and Numerical Simulation is the only available book that extends the classical field of fluid dynamics into the realm of scientific computing in a way that is both comprehensive and accessible to the beginner. The theory of fluid dynamics, and the implementation of solution procedures into numerical algorithms, are discussed hand-in-hand and with reference to computer programming. This book is an accessible introduction to theoretical and computational fluid dynamics (CFD), written from a modern perspective that unifies theory and numerical practice. There are several additions and subject expansions in the Second Edition of Fluid Dynamics, including new Matlab and FORTRAN codes. Two distinguishing features of the discourse are: solution procedures and algorithms are developed immediately after problem formulations are presented, and numerical methods are introduced on a need-to-know basis and in increasing order of difficulty. Matlab codes are presented and discussed for ...
An introduction to Computational Fluid Dynamics
DEFF Research Database (Denmark)
Sørensen, Lars Schiøtt
1999-01-01
CFD is the shortname for Computational Fluid Dynamics and is a numerical method by means of which we can analyze systems containing fluids. For instance systems dealing with heat flow or smoke control systems acting when a fire occur in a building.......CFD is the shortname for Computational Fluid Dynamics and is a numerical method by means of which we can analyze systems containing fluids. For instance systems dealing with heat flow or smoke control systems acting when a fire occur in a building....
Fluid dynamics computer programs for NERVA turbopump
Brunner, J. J.
1972-01-01
During the design of the NERVA turbopump, numerous computer programs were developed for the analyses of fluid dynamic problems within the machine. Program descriptions, example cases, users instructions, and listings for the majority of these programs are presented.
Fluid dynamics theory, computation, and numerical simulation
Pozrikidis, C
2017-01-01
This book provides an accessible introduction to the basic theory of fluid mechanics and computational fluid dynamics (CFD) from a modern perspective that unifies theory and numerical computation. Methods of scientific computing are introduced alongside with theoretical analysis and MATLAB® codes are presented and discussed for a broad range of topics: from interfacial shapes in hydrostatics, to vortex dynamics, to viscous flow, to turbulent flow, to panel methods for flow past airfoils. The third edition includes new topics, additional examples, solved and unsolved problems, and revised images. It adds more computational algorithms and MATLAB programs. It also incorporates discussion of the latest version of the fluid dynamics software library FDLIB, which is freely available online. FDLIB offers an extensive range of computer codes that demonstrate the implementation of elementary and advanced algorithms and provide an invaluable resource for research, teaching, classroom instruction, and self-study. This ...
Artificial Intelligence In Computational Fluid Dynamics
Vogel, Alison Andrews
1991-01-01
Paper compares four first-generation artificial-intelligence (Al) software systems for computational fluid dynamics. Includes: Expert Cooling Fan Design System (EXFAN), PAN AIR Knowledge System (PAKS), grid-adaptation program MITOSIS, and Expert Zonal Grid Generation (EZGrid). Focuses on knowledge-based ("expert") software systems. Analyzes intended tasks, kinds of knowledge possessed, magnitude of effort required to codify knowledge, how quickly constructed, performances, and return on investment. On basis of comparison, concludes Al most successful when applied to well-formulated problems solved by classifying or selecting preenumerated solutions. In contrast, application of Al to poorly understood or poorly formulated problems generally results in long development time and large investment of effort, with no guarantee of success.
Computational fluid dynamic modelling of cavitation
Deshpande, Manish; Feng, Jinzhang; Merkle, Charles L.
1993-01-01
Models in sheet cavitation in cryogenic fluids are developed for use in Euler and Navier-Stokes codes. The models are based upon earlier potential-flow models but enable the cavity inception point, length, and shape to be determined as part of the computation. In the present paper, numerical solutions are compared with experimental measurements for both pressure distribution and cavity length. Comparisons between models are also presented. The CFD model provides a relatively simple modification to an existing code to enable cavitation performance predictions to be included. The analysis also has the added ability of incorporating thermodynamic effects of cryogenic fluids into the analysis. Extensions of the current two-dimensional steady state analysis to three-dimensions and/or time-dependent flows are, in principle, straightforward although geometrical issues become more complicated. Linearized models, however offer promise of providing effective cavitation modeling in three-dimensions. This analysis presents good potential for improved understanding of many phenomena associated with cavity flows.
Colour in visualisation for computational fluid dynamics
Kinnear, D; Atherton, MA; Collins, MW; Dokhan, J; Karayiannis, TG
2006-01-01
Colour is used in computational fluid dynamic (CFD) simulations in two key ways. First it is used to visualise the geometry and allow the engineers to be confident that the model constructed is a good representation of the engineering situation. Once an analysis has been completed, colour is used in post-processing the data from the simulations to illustrate the complex fluid mechanic phenomena under investigation. This paper describes these two uses of colour and provides some examples to il...
Computational Fluid Dynamics and Room Air Movement
DEFF Research Database (Denmark)
Nielsen, Peter Vilhelm
2004-01-01
on the mass fraction transport equation. The importance of ?false? or numerical diffusion is also addressed in connection with the simple description of a supply opening. The different aspects of boundary conditions in the indoor environment as e.g. the simulation of Air Terminal Devices and the simulation......Nielsen, P.V. Computational Fluid Dynamics and Room Air Movement. Indoor Air, International Journal of Indoor Environment and Health, Vol. 14, Supplement 7, pp. 134-143, 2004. ABSTRACT Computational Fluid Dynamics (CFD) and new developments of CFD in the indoor environment as well as quality...... considerations are important elements in the study of energy consumption, thermal comfort and indoor air quality in buildings. The paper discusses the quality level of Computational Fluid Dynamics and the involved schemes (first, second and third order schemes) by the use of the Smith and Hutton problem...
Human Computer Music Performance
Dannenberg, Roger B.
2012-01-01
Human Computer Music Performance (HCMP) is the study of music performance by live human performers and real-time computer-based performers. One goal of HCMP is to create a highly autonomous artificial performer that can fill the role of a human, especially in a popular music setting. This will require advances in automated music listening and understanding, new representations for music, techniques for music synchronization, real-time human-computer communication, music generation, sound synt...
Computational fluid mechanics and heat transfer
Pletcher, Richard H; Anderson, Dale
2012-01-01
""I have always considered this book the best gift from one generation to the next in computational fluid dynamics. I earnestly recommend this book to graduate students and practicing engineers for the pleasure of learning and a handy reference. The description of the basic concepts and fundamentals is thorough and is crystal clear for understanding. And since 1984, two newer editions have kept abreast to the new, relevant, and fully verified advancements in CFD.""-Joseph J.S. Shang, Wright State University""Computational Fluid Mechanics and Heat Transfer is very well written to be used as a t
Three-Dimensional Computational Fluid Dynamics
Energy Technology Data Exchange (ETDEWEB)
Haworth, D.C.; O' Rourke, P.J.; Ranganathan, R.
1998-09-01
Computational fluid dynamics (CFD) is one discipline falling under the broad heading of computer-aided engineering (CAE). CAE, together with computer-aided design (CAD) and computer-aided manufacturing (CAM), comprise a mathematical-based approach to engineering product and process design, analysis and fabrication. In this overview of CFD for the design engineer, our purposes are three-fold: (1) to define the scope of CFD and motivate its utility for engineering, (2) to provide a basic technical foundation for CFD, and (3) to convey how CFD is incorporated into engineering product and process design.
Engineering Fracking Fluids with Computer Simulation
Shaqfeh, Eric
2015-11-01
There are no comprehensive simulation-based tools for engineering the flows of viscoelastic fluid-particle suspensions in fully three-dimensional geometries. On the other hand, the need for such a tool in engineering applications is immense. Suspensions of rigid particles in viscoelastic fluids play key roles in many energy applications. For example, in oil drilling the ``drilling mud'' is a very viscous, viscoelastic fluid designed to shear-thin during drilling, but thicken at stoppage so that the ``cuttings'' can remain suspended. In a related application known as hydraulic fracturing suspensions of solids called ``proppant'' are used to prop open the fracture by pumping them into the well. It is well-known that particle flow and settling in a viscoelastic fluid can be quite different from that which is observed in Newtonian fluids. First, it is now well known that the ``fluid particle split'' at bifurcation cracks is controlled by fluid rheology in a manner that is not understood. Second, in Newtonian fluids, the presence of an imposed shear flow in the direction perpendicular to gravity (which we term a cross or orthogonal shear flow) has no effect on the settling of a spherical particle in Stokes flow (i.e. at vanishingly small Reynolds number). By contrast, in a non-Newtonian liquid, the complex rheological properties induce a nonlinear coupling between the sedimentation and shear flow. Recent experimental data have shown both the shear thinning and the elasticity of the suspending polymeric solutions significantly affects the fluid-particle split at bifurcations, as well as the settling rate of the solids. In the present work, we use the Immersed Boundary Method to develop computer simulations of viscoelastic flow in suspensions of spheres to study these problems. These simulations allow us to understand the detailed physical mechanisms for the remarkable physical behavior seen in practice, and actually suggest design rules for creating new fluid recipes.
Engineering applications of computational fluid dynamics
Awang, Mokhtar
2015-01-01
This volume presents the results of Computational Fluid Dynamics (CFD) analysis that can be used for conceptual studies of product design, detail product development, process troubleshooting. It demonstrates the benefit of CFD modeling as a cost saving, timely, safe and easy to scale-up methodology.
AIR INGRESS ANALYSIS: COMPUTATIONAL FLUID DYNAMIC MODELS
Energy Technology Data Exchange (ETDEWEB)
Chang H. Oh; Eung S. Kim; Richard Schultz; Hans Gougar; David Petti; Hyung S. Kang
2010-08-01
The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena Identification and Ranking Studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important with regard to core safety. Consequently, the development of advanced air ingress-related models and verification and validation data are a very high priority. Following a loss of coolant and system depressurization incident, air will enter the core of the High Temperature Gas Cooled Reactor through the break, possibly causing oxidation of the in-the core and reflector graphite structure. Simple core and plant models indicate that, under certain circumstances, the oxidation may proceed at an elevated rate with additional heat generated from the oxidation reaction itself. Under postulated conditions of fluid flow and temperature, excessive degradation of the lower plenum graphite can lead to a loss of structural support. Excessive oxidation of core graphite can also lead to the release of fission products into the confinement, which could be detrimental to a reactor safety. Computational fluid dynamic model developed in this study will improve our understanding of this phenomenon. This paper presents two-dimensional and three-dimensional CFD results for the quantitative assessment of the air ingress phenomena. A portion of results of the density-driven stratified flow in the inlet pipe will be compared with results of the experimental results.
Computational fluid dynamics a practical approach
Tu, Jiyuan; Liu, Chaoqun
2018-01-01
Computational Fluid Dynamics: A Practical Approach, Third Edition, is an introduction to CFD fundamentals and commercial CFD software to solve engineering problems. The book is designed for a wide variety of engineering students new to CFD, and for practicing engineers learning CFD for the first time. Combining an appropriate level of mathematical background, worked examples, computer screen shots, and step-by-step processes, this book walks the reader through modeling and computing, as well as interpreting CFD results. This new edition has been updated throughout, with new content and improved figures, examples and problems.
Savoir Fluide. A newsletter on computational hydraulics and fluid dynamics
International Nuclear Information System (INIS)
1997-01-01
This newsletter reports on computational works performed by the National Laboratory of Hydraulics (LNH) from Electricite de France (EdF). Two papers were selected which concern the simulation of the Paluel nuclear power plant plume and the computation of particles and droplets inside a cooling tower. (J.S.)
Ecotoxicological testing of performance fluids
International Nuclear Information System (INIS)
Kallqvist, T.
1990-05-01
The report deals with a project comprising the testing of drilling fluids concerning ecotoxicology, biological degradation, and toxicity. Two types of drilling fluids were tested for toxic effects on marine algae and biological degradability. A fluid based on mineral oil was readily degradable (98% DOC removal in 28 days) while an ether based oil degraded more slowly (56% DOC removal in 28 days). The toxicity of both fluids was tested after emulsification of the oils in water and separating the oil and water phase after equilibration. The EC 50 values obtained with this approach were 8.15 g/l for the oil based fluid and 116 g/l for the ether fluid. 9 figs., 8 tabs
Zonal methods and computational fluid dynamics
International Nuclear Information System (INIS)
Atta, E.H.
1985-01-01
Recent advances in developing numerical algorithms for solving fluid flow problems, and the continuing improvement in the speed and storage of large scale computers have made it feasible to compute the flow field about complex and realistic configurations. Current solution methods involve the use of a hierarchy of mathematical models ranging from the linearized potential equation to the Navier Stokes equations. Because of the increasing complexity of both the geometries and flowfields encountered in practical fluid flow simulation, there is a growing emphasis in computational fluid dynamics on the use of zonal methods. A zonal method is one that subdivides the total flow region into interconnected smaller regions or zones. The flow solutions in these zones are then patched together to establish the global flow field solution. Zonal methods are primarily used either to limit the complexity of the governing flow equations to a localized region or to alleviate the grid generation problems about geometrically complex and multicomponent configurations. This paper surveys the application of zonal methods for solving the flow field about two and three-dimensional configurations. Various factors affecting their accuracy and ease of implementation are also discussed. From the presented review it is concluded that zonal methods promise to be very effective for computing complex flowfields and configurations. Currently there are increasing efforts to improve their efficiency, versatility, and accuracy
Computational fluid dynamics in ventilation: Practical approach
Fontaine, J. R.
The potential of computation fluid dynamics (CFD) for conceiving ventilation systems is shown through the simulation of five practical cases. The following examples are considered: capture of pollutants on a surface treating tank equipped with a unilateral suction slot in the presence of a disturbing air draft opposed to suction; dispersion of solid aerosols inside fume cupboards; performances comparison of two general ventilation systems in a silkscreen printing workshop; ventilation of a large open painting area; and oil fog removal inside a mechanical engineering workshop. Whereas the two first problems are analyzed through two dimensional numerical simulations, the three other cases require three dimensional modeling. For the surface treating tank case, numerical results are compared to laboratory experiment data. All simulations are carried out using EOL, a CFD software specially devised to deal with air quality problems in industrial ventilated premises. It contains many analysis tools to interpret the results in terms familiar to the industrial hygienist. Much experimental work has been engaged to validate the predictions of EOL for ventilation flows.
Review of computational fluid dynamics (CFD) researches on nano fluid flow through micro channel
Dewangan, Satish Kumar
2018-05-01
Nanofluid is becoming a promising heat transfer fluids due to its improved thermo-physical properties and heat transfer performance. Micro channel heat transfer has potential application in the cooling high power density microchips in CPU system, micro power systems and many such miniature thermal systems which need advanced cooling capacity. Use of nanofluids enhances the effectiveness of t=scu systems. Computational Fluid Dynamics (CFD) is a very powerful tool in computational analysis of the various physical processes. It application to the situations of flow and heat transfer analysis of the nano fluids is catching up very fast. Present research paper gives a brief account of the methodology of the CFD and also summarizes its application on nano fluid and heat transfer for microchannel cases.
International Nuclear Information System (INIS)
Baek, Seung Man; Nam, Jin Hyun; Hong, Hiki; Kim, Charn-Jung
2011-01-01
This study numerically investigates the effect of the brine flow rate on the thermal performance of a spiral-jacketed thermal storage tank (TST) installed in a solar domestic hot water (SDHW) system. The spiral-jacketed TST is a TST with a mantle heat exchanger, consisting of a vertical, cylindrical water tank for energy storage and a spiral brine flow path attached to the tank wall for heat transfer. A computational fluid dynamics (CFD) model was constructed based on the actual geometry of a spiral-jacketed TST. In addition, the boundary conditions were defined by considering solar radiation and ambient temperature data that were measured during experimental operation of the SDHW system. The numerical results demonstrated that an increase in the brine flow rate enhances the thermal efficiency of the TST due to higher heat transfer coefficients in the spiral path, and also leads to reduced thermal stratification in the TST. On the other hand, a lower brine flow rate increased the heat transfer rate at the inlet of the spiral path near the top of the TST, which resulted in enhanced thermal stratification. The optimal range for the rate of brine flow rate is discussed with respect to the thermal efficiency of the TST and the required pumping power for brine circulation in the spiral flow path. - Highlights: → A CFD model was developed for a spiral-jacketed thermal storage tank (TST) installed in a solar domestic hot water (SDHW) system. → Effects of brine flow rate on the overall performance of the spiral-jacketed TST were numerically investigated. → Higher brine flow rates slightly increased the solar energy acquired by the TST, but it also increased the pump power required to circulate the brine. → Lower brine flow rates were found to be a better option for the spiral-jacketed TST, by maximizing the exergy of the SDHW system.
Applied Computational Fluid Dynamics at NASA Ames Research Center
Holst, Terry L.; Kwak, Dochan (Technical Monitor)
1994-01-01
The field of Computational Fluid Dynamics (CFD) has advanced to the point where it can now be used for many applications in fluid mechanics research and aerospace vehicle design. A few applications being explored at NASA Ames Research Center will be presented and discussed. The examples presented will range in speed from hypersonic to low speed incompressible flow applications. Most of the results will be from numerical solutions of the Navier-Stokes or Euler equations in three space dimensions for general geometry applications. Computational results will be used to highlight the presentation as appropriate. Advances in computational facilities including those associated with NASA's CAS (Computational Aerosciences) Project of the Federal HPCC (High Performance Computing and Communications) Program will be discussed. Finally, opportunities for future research will be presented and discussed. All material will be taken from non-sensitive, previously-published and widely-disseminated work.
Computational fluid dynamics (CFD) simulation of hot air flow ...
African Journals Online (AJOL)
Computational Fluid Dynamics simulation of air flow distribution, air velocity and pressure field pattern as it will affect moisture transient in a cabinet tray dryer is performed using SolidWorks Flow Simulation (SWFS) 2014 SP 4.0 program. The model used for the drying process in this experiment was designed with Solid ...
Computational fluid dynamics in ventilation design
Allard, Francis; Awbi, Hazim B; Davidson, Lars; Schälin, Alois
2007-01-01
CFD-calculations have been rapidly developed to a powerful tool for the analysis of air pollution distribution in various spaces. However, the user of CFD-calculation should be aware of the basic principles of calculations and specifically the boundary conditions. Computational Fluid Dynamics (CFD) – in Ventilation Design models is written by a working group of highly qualified international experts representing research, consulting and design.
Multi-dimensional two-fluid flow computation. An overview
International Nuclear Information System (INIS)
Carver, M.B.
1992-01-01
This paper discusses a repertoire of three-dimensional computer programs developed to perform critical analysis of single-phase, two-phase and multi-fluid flow in reactor components. The basic numerical approach to solving the governing equations common to all the codes is presented and the additional constitutive relationships required for closure are discussed. Particular applications are presented for a number of computer codes. (author). 12 refs
The use of computers for instruction in fluid dynamics
Watson, Val
1987-01-01
Applications for computers which improve instruction in fluid dynamics are examined. Computers can be used to illustrate three-dimensional flow fields and simple fluid dynamics mechanisms, to solve fluid dynamics problems, and for electronic sketching. The usefulness of computer applications is limited by computer speed, memory, and software and the clarity and field of view of the projected display. Proposed advances in personal computers which will address these limitations are discussed. Long range applications for computers in education are considered.
Cardioplegia heat exchanger design modelling using computational fluid dynamics.
van Driel, M R
2000-11-01
A new cardioplegia heat exchanger has been developed by Sorin Biomedica. A three-dimensional computer-aided design (CAD) model was optimized using computational fluid dynamics (CFD) modelling. CFD optimization techniques have commonly been applied to velocity flow field analysis, but CFD analysis was also used in this study to predict the heat exchange performance of the design before prototype fabrication. The iterative results of the optimization and the actual heat exchange performance of the final configuration are presented in this paper. Based on the behaviour of this model, both the water and blood fluid flow paths of the heat exchanger were optimized. The simulation predicted superior heat exchange performance using an optimal amount of energy exchange surface area, reducing the total contact surface area, the device priming volume and the material costs. Experimental results confirm the empirical results predicted by the CFD analysis.
Computational Fluid Dynamics in Ventilation Design
DEFF Research Database (Denmark)
Nielsen, Peter V.
2008-01-01
This paper is based on the new REHVA Guidebook Computational Fluid Dynamics in Ventilation Design (Nielsen et al. 2007) written by Peter V. Nielsen, Francis(Nielsen 2007) written by Peter V. Nielsen, Francis Allard, Hazim B. Awbi, Lars Davidson and Alois Schälin. The guidebook is made for people....... The guidebook introduces rules for good quality prediction work, and it is the purpose of the guidebook to improve the technical level of CFD work in ventilation.......This paper is based on the new REHVA Guidebook Computational Fluid Dynamics in Ventilation Design (Nielsen et al. 2007) written by Peter V. Nielsen, Francis(Nielsen 2007) written by Peter V. Nielsen, Francis Allard, Hazim B. Awbi, Lars Davidson and Alois Schälin. The guidebook is made for people...... who need to use and discuss results based on CFD predictions, and it gives insight into the subject for those who are not used to work with CFD. The guidebook is also written for people working with CFD who have to be more aware of how this numerical method is applied in the area of ventilation...
High Performance Computing Multicast
2012-02-01
A History of the Virtual Synchrony Replication Model,” in Replication: Theory and Practice, Charron-Bost, B., Pedone, F., and Schiper, A. (Eds...Performance Computing IP / IPv4 Internet Protocol (version 4.0) IPMC Internet Protocol MultiCast LAN Local Area Network MCMD Dr. Multicast MPI
Data Point Averaging for Computational Fluid Dynamics Data
Norman, Jr., David (Inventor)
2016-01-01
A system and method for generating fluid flow parameter data for use in aerodynamic heating analysis. Computational fluid dynamics data is generated for a number of points in an area on a surface to be analyzed. Sub-areas corresponding to areas of the surface for which an aerodynamic heating analysis is to be performed are identified. A computer system automatically determines a sub-set of the number of points corresponding to each of the number of sub-areas and determines a value for each of the number of sub-areas using the data for the sub-set of points corresponding to each of the number of sub-areas. The value is determined as an average of the data for the sub-set of points corresponding to each of the number of sub-areas. The resulting parameter values then may be used to perform an aerodynamic heating analysis.
CFDLIB05, Computational Fluid Dynamics Library
International Nuclear Information System (INIS)
Kashiwa, B.A.; Padial, N.T.; Rauenzahn, R.M.; VanderHeyden, W.B.
2007-01-01
1 - Description of program or function: CFDLib05 is the Los Alamos Computational Fluid Dynamics Library. This is a collection of hydro-codes using a common data structure and a common numerical method, for problems ranging from single-field, incompressible flow, to multi-species, multi-field, compressible flow. The data structure is multi-block, with a so-called structured grid in each block. The numerical method is a Finite-Volume scheme employing a state vector that is fully cell-centered. This means that the integral form of the conversation laws is solved on the physical domain that is represented by a mesh of control volumes. The typical control volume is an arbitrary quadrilateral in 2D and an arbitrary hexahedron in 3D. The Finite-Volume scheme is for time-unsteady flow and remains well coupled by means of time and space centered fluxes; if a steady state solution is required, the problem is integrated forward in time until the user is satisfied that the state is stationary. 2 - Methods: Cells-centered Implicit Continuous-fluid Eulerian (ICE) method
Computational fluid dynamics modelling in cardiovascular medicine.
Morris, Paul D; Narracott, Andrew; von Tengg-Kobligk, Hendrik; Silva Soto, Daniel Alejandro; Hsiao, Sarah; Lungu, Angela; Evans, Paul; Bressloff, Neil W; Lawford, Patricia V; Hose, D Rodney; Gunn, Julian P
2016-01-01
This paper reviews the methods, benefits and challenges associated with the adoption and translation of computational fluid dynamics (CFD) modelling within cardiovascular medicine. CFD, a specialist area of mathematics and a branch of fluid mechanics, is used routinely in a diverse range of safety-critical engineering systems, which increasingly is being applied to the cardiovascular system. By facilitating rapid, economical, low-risk prototyping, CFD modelling has already revolutionised research and development of devices such as stents, valve prostheses, and ventricular assist devices. Combined with cardiovascular imaging, CFD simulation enables detailed characterisation of complex physiological pressure and flow fields and the computation of metrics which cannot be directly measured, for example, wall shear stress. CFD models are now being translated into clinical tools for physicians to use across the spectrum of coronary, valvular, congenital, myocardial and peripheral vascular diseases. CFD modelling is apposite for minimally-invasive patient assessment. Patient-specific (incorporating data unique to the individual) and multi-scale (combining models of different length- and time-scales) modelling enables individualised risk prediction and virtual treatment planning. This represents a significant departure from traditional dependence upon registry-based, population-averaged data. Model integration is progressively moving towards 'digital patient' or 'virtual physiological human' representations. When combined with population-scale numerical models, these models have the potential to reduce the cost, time and risk associated with clinical trials. The adoption of CFD modelling signals a new era in cardiovascular medicine. While potentially highly beneficial, a number of academic and commercial groups are addressing the associated methodological, regulatory, education- and service-related challenges. Published by the BMJ Publishing Group Limited. For permission
Performing stencil computations
Energy Technology Data Exchange (ETDEWEB)
Donofrio, David
2018-01-16
A method and apparatus for performing stencil computations efficiently are disclosed. In one embodiment, a processor receives an offset, and in response, retrieves a value from a memory via a single instruction, where the retrieving comprises: identifying, based on the offset, one of a plurality of registers of the processor; loading an address stored in the identified register; and retrieving from the memory the value at the address.
Direct modeling for computational fluid dynamics
Xu, Kun
2015-06-01
All fluid dynamic equations are valid under their modeling scales, such as the particle mean free path and mean collision time scale of the Boltzmann equation and the hydrodynamic scale of the Navier-Stokes (NS) equations. The current computational fluid dynamics (CFD) focuses on the numerical solution of partial differential equations (PDEs), and its aim is to get the accurate solution of these governing equations. Under such a CFD practice, it is hard to develop a unified scheme that covers flow physics from kinetic to hydrodynamic scales continuously because there is no such governing equation which could make a smooth transition from the Boltzmann to the NS modeling. The study of fluid dynamics needs to go beyond the traditional numerical partial differential equations. The emerging engineering applications, such as air-vehicle design for near-space flight and flow and heat transfer in micro-devices, do require further expansion of the concept of gas dynamics to a larger domain of physical reality, rather than the traditional distinguishable governing equations. At the current stage, the non-equilibrium flow physics has not yet been well explored or clearly understood due to the lack of appropriate tools. Unfortunately, under the current numerical PDE approach, it is hard to develop such a meaningful tool due to the absence of valid PDEs. In order to construct multiscale and multiphysics simulation methods similar to the modeling process of constructing the Boltzmann or the NS governing equations, the development of a numerical algorithm should be based on the first principle of physical modeling. In this paper, instead of following the traditional numerical PDE path, we introduce direct modeling as a principle for CFD algorithm development. Since all computations are conducted in a discretized space with limited cell resolution, the flow physics to be modeled has to be done in the mesh size and time step scales. Here, the CFD is more or less a direct
High-performance computing using FPGAs
Benkrid, Khaled
2013-01-01
This book is concerned with the emerging field of High Performance Reconfigurable Computing (HPRC), which aims to harness the high performance and relative low power of reconfigurable hardware–in the form Field Programmable Gate Arrays (FPGAs)–in High Performance Computing (HPC) applications. It presents the latest developments in this field from applications, architecture, and tools and methodologies points of view. We hope that this work will form a reference for existing researchers in the field, and entice new researchers and developers to join the HPRC community. The book includes: Thirteen application chapters which present the most important application areas tackled by high performance reconfigurable computers, namely: financial computing, bioinformatics and computational biology, data search and processing, stencil computation e.g. computational fluid dynamics and seismic modeling, cryptanalysis, astronomical N-body simulation, and circuit simulation. Seven architecture chapters which...
Distributed interactive graphics applications in computational fluid dynamics
International Nuclear Information System (INIS)
Rogers, S.E.; Buning, P.G.; Merritt, F.J.
1987-01-01
Implementation of two distributed graphics programs used in computational fluid dynamics is discussed. Both programs are interactive in nature. They run on a CRAY-2 supercomputer and use a Silicon Graphics Iris workstation as the front-end machine. The hardware and supporting software are from the Numerical Aerodynamic Simulation project. The supercomputer does all numerically intensive work and the workstation, as the front-end machine, allows the user to perform real-time interactive transformations on the displayed data. The first program was written as a distributed program that computes particle traces for fluid flow solutions existing on the supercomputer. The second is an older post-processing and plotting program modified to run in a distributed mode. Both programs have realized a large increase in speed over that obtained using a single machine. By using these programs, one can learn quickly about complex features of a three-dimensional flow field. Some color results are presented
Verification and validation in computational fluid dynamics
Oberkampf, William L.; Trucano, Timothy G.
2002-04-01
Verification and validation (V&V) are the primary means to assess accuracy and reliability in computational simulations. This paper presents an extensive review of the literature in V&V in computational fluid dynamics (CFD), discusses methods and procedures for assessing V&V, and develops a number of extensions to existing ideas. The review of the development of V&V terminology and methodology points out the contributions from members of the operations research, statistics, and CFD communities. Fundamental issues in V&V are addressed, such as code verification versus solution verification, model validation versus solution validation, the distinction between error and uncertainty, conceptual sources of error and uncertainty, and the relationship between validation and prediction. The fundamental strategy of verification is the identification and quantification of errors in the computational model and its solution. In verification activities, the accuracy of a computational solution is primarily measured relative to two types of highly accurate solutions: analytical solutions and highly accurate numerical solutions. Methods for determining the accuracy of numerical solutions are presented and the importance of software testing during verification activities is emphasized. The fundamental strategy of validation is to assess how accurately the computational results compare with the experimental data, with quantified error and uncertainty estimates for both. This strategy employs a hierarchical methodology that segregates and simplifies the physical and coupling phenomena involved in the complex engineering system of interest. A hypersonic cruise missile is used as an example of how this hierarchical structure is formulated. The discussion of validation assessment also encompasses a number of other important topics. A set of guidelines is proposed for designing and conducting validation experiments, supported by an explanation of how validation experiments are different
Computational Fluid Dynamics Modeling of Bacillus anthracis ...
Journal Article Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived from computed tomography (CT) or µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation-exhalation breathing conditions using average species-specific minute volumes. Four different exposure scenarios were modeled in the rabbit based upon experimental inhalation studies. For comparison, human simulations were conducted at the highest exposure concentration used during the rabbit experimental exposures. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Despite the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the upper conducting airways of the human at the same air concentration of anthrax spores. This greater deposition of spores in the upper airways in the human resulted in lower penetration and deposition in the tracheobronchial airways and the deep lung than that predict
Computational fluid dynamics for sport simulation
2009-01-01
All over the world sport plays a prominent role in society: as a leisure activity for many, as an ingredient of culture, as a business and as a matter of national prestige in such major events as the World Cup in soccer or the Olympic Games. Hence, it is not surprising that science has entered the realm of sports, and, in particular, that computer simulation has become highly relevant in recent years. This is explored in this book by choosing five different sports as examples, demonstrating that computational science and engineering (CSE) can make essential contributions to research on sports topics on both the fundamental level and, eventually, by supporting athletes’ performance.
Fluid dynamics theoretical and computational approaches
Warsi, ZUA
2005-01-01
Important Nomenclature Kinematics of Fluid Motion Introduction to Continuum Motion Fluid Particles Inertial Coordinate Frames Motion of a Continuum The Time Derivatives Velocity and Acceleration Steady and Nonsteady Flow Trajectories of Fluid Particles and Streamlines Material Volume and Surface Relation between Elemental Volumes Kinematic Formulas of Euler and Reynolds Control Volume and Surface Kinematics of Deformation Kinematics of Vorticity and Circulation References Problems The Conservation Laws and the Kinetics of Flow Fluid Density and the Conservation of Mass Prin
Research in Applied Mathematics, Fluid Mechanics and Computer Science
1999-01-01
This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period October 1, 1998 through March 31, 1999.
[Research activities in applied mathematics, fluid mechanics, and computer science
1995-01-01
This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period April 1, 1995 through September 30, 1995.
Energy performance indicator report: fluid milk plants
Energy Technology Data Exchange (ETDEWEB)
NONE
2001-07-01
In Canada, the dairy sector consumes significant amounts of energy and is looking for new ways of saving energy. The aim of this study, performed by the Competitive Analysis Centre Inc., was to find novel energy savings ideas for fluid milk plants. For this purpose, the energy consumption of 17 fluid milk plants, which accounts for over 50% of total Canadian output, was analyzed; first, at the plant level, and then by 8 categories at the sub-plant level in order to develop benchmarks that could be applied at both these levels. The paper provides background information on Canada's fluid milk sector and outlines the methodology used to develop and apply energy efficiency measures in the sector; the study findings are also presented. This report found that the energy consumption of the Canadian fluid milk sector could be lowered by applying the energy saving proposals developed herein.
Computational fluid dynamics principles and applications
Blazek, J
2005-01-01
Computational Fluid Dynamics (CFD) is an important design tool in engineering and also a substantial research tool in various physical sciences as well as in biology. The objective of this book is to provide university students with a solid foundation for understanding the numerical methods employed in today's CFD and to familiarise them with modern CFD codes by hands-on experience. It is also intended for engineers and scientists starting to work in the field of CFD or for those who apply CFD codes. Due to the detailed index, the text can serve as a reference handbook too. Each chapter includes an extensive bibliography, which provides an excellent basis for further studies. The accompanying companion website contains the sources of 1-D and 2-D Euler and Navier-Stokes flow solvers (structured and unstructured) as well as of grid generators. Provided are also tools for Von Neumann stability analysis of 1-D model equations. Finally, the companion website includes the source code of a dedicated visualisation so...
Application of GPU to computational multiphase fluid dynamics
International Nuclear Information System (INIS)
Nagatake, T; Kunugi, T
2010-01-01
The MARS (Multi-interfaces Advection and Reconstruction Solver) [1] is one of the surface volume tracking methods for multi-phase flows. Nowadays, the performance of GPU (Graphics Processing Unit) is much higher than the CPU (Central Processing Unit). In this study, the GPU was applied to the MARS in order to accelerate the computation of multi-phase flows (GPU-MARS), and the performance of the GPU-MARS was discussed. From the performance of the interface tracking method for the analyses of one-directional advection problem, it is found that the computing time of GPU(single GTX280) was around 4 times faster than that of the CPU (Xeon 5040, 4 threads parallelized). From the performance of Poisson Solver by using the algorithm developed in this study, it is found that the performance of the GPU showed around 30 times faster than that of the CPU. Finally, it is confirmed that the GPU showed the large acceleration of the fluid flow computation (GPU-MARS) compared to the CPU. However, it is also found that the double-precision computation of the GPU must perform with very high precision.
Computational Fluid Dynamics Methods and Their Applications in Medical Science
Directory of Open Access Journals (Sweden)
Kowalewski Wojciech
2016-12-01
Full Text Available As defined by the National Institutes of Health: “Biomedical engineering integrates physical, chemical, mathematical, and computational sciences and engineering principles to study biology, medicine, behavior, and health”. Many issues in this area are closely related to fluid dynamics. This paper provides an overview of the basic concepts concerning Computational Fluid Dynamics and its applications in medicine.
Computational Fluid Dynamics (CFD) simulations of a Heisenberg Vortex Tube
Bunge, Carl; Sitaraman, Hariswaran; Leachman, Jake
2017-11-01
A 3D Computational Fluid Dynamics (CFD) simulation of a Heisenberg Vortex Tube (HVT) is performed to estimate cooling potential with cryogenic hydrogen. The main mechanism driving operation of the vortex tube is the use of fluid power for enthalpy streaming in a highly turbulent swirl in a dual-outlet tube. This enthalpy streaming creates a temperature separation between the outer and inner regions of the flow. Use of a catalyst on the peripheral wall of the centrifuge enables endothermic conversion of para-ortho hydrogen to aid primary cooling. A κ- ɛ turbulence model is used with a cryogenic, non-ideal equation of state, and para-orthohydrogen species evolution. The simulations are validated with experiments and strategies for parametric optimization of this device are presented.
Modeling fires in adjacent ship compartments with computational fluid dynamics
International Nuclear Information System (INIS)
Wix, S.D.; Cole, J.K.; Koski, J.A.
1998-01-01
This paper presents an analysis of the thermal effects on radioactive (RAM) transportation pack ages with a fire in an adjacent compartment. An assumption for this analysis is that the adjacent hold fire is some sort of engine room fire. Computational fluid dynamics (CFD) analysis tools were used to perform the analysis in order to include convective heat transfer effects. The analysis results were compared to experimental data gathered in a series of tests on the United States Coast Guard ship Mayo Lykes located at Mobile, Alabama. (authors)
Torque converter transient characteristics prediction using computational fluid dynamics
International Nuclear Information System (INIS)
Yamaguchi, T; Tanaka, K
2012-01-01
The objective of this research is to investigate the transient torque converter performance used in an automobile. A new technique in computational fluid dynamics is introduced, which includes the inertia of the turbine in a three dimensional simulation of the torque converter during a launch condition. The simulation results are compared to experimental test data with good agreement across the range of data. In addition, the simulated flow structure inside the torque converter is visualized and compared to results from a steady-state calculation.
High-pressure fluid phase equilibria phenomenology and computation
Deiters, Ulrich K
2012-01-01
The book begins with an overview of the phase diagrams of fluid mixtures (fluid = liquid, gas, or supercritical state), which can show an astonishing variety when elevated pressures are taken into account; phenomena like retrograde condensation (single and double) and azeotropy (normal and double) are discussed. It then gives an introduction into the relevant thermodynamic equations for fluid mixtures, including some that are rarely found in modern textbooks, and shows how they can they be used to compute phase diagrams and related properties. This chapter gives a consistent and axiomatic approach to fluid thermodynamics; it avoids using activity coefficients. Further chapters are dedicated to solid-fluid phase equilibria and global phase diagrams (systematic search for phase diagram classes). The appendix contains numerical algorithms needed for the computations. The book thus enables the reader to create or improve computer programs for the calculation of fluid phase diagrams. introduces phase diagram class...
Self-study manual for introduction to computational fluid dynamics
Nabatov, Andrey
2017-01-01
Computational Fluid Dynamics (CFD) is the branch of Fluid Mechanics and Computational Physics that plays a decent role in modern Mechanical Engineering Design process due to such advantages as relatively low cost of simulation comparing with conduction of real experiment, an opportunity to easily correct the design of a prototype prior to manufacturing of the final product and a wide range of application: mixing, acoustics, cooling and aerodynamics. This makes CFD particularly and Computation...
Description of a method for computing fluid-structure interaction
International Nuclear Information System (INIS)
Gantenbein, F.
1982-02-01
A general formulation allowing computation of structure vibrations in a dense fluid is described. It is based on fluid modelisation by fluid finite elements. For each fluid node are associated two variables: the pressure p and a variable π defined as p=d 2 π/dt 2 . Coupling between structure and fluid is introduced by surface elements. This method is easy to introduce in a general finite element code. Validation was obtained by analytical calculus and tests. It is widely used for vibrational and seismic studies of pipes and internals of nuclear reactors some applications are presented [fr
Computational fluid dynamics incompressible turbulent flows
Kajishima, Takeo
2017-01-01
This textbook presents numerical solution techniques for incompressible turbulent flows that occur in a variety of scientific and engineering settings including aerodynamics of ground-based vehicles and low-speed aircraft, fluid flows in energy systems, atmospheric flows, and biological flows. This book encompasses fluid mechanics, partial differential equations, numerical methods, and turbulence models, and emphasizes the foundation on how the governing partial differential equations for incompressible fluid flow can be solved numerically in an accurate and efficient manner. Extensive discussions on incompressible flow solvers and turbulence modeling are also offered. This text is an ideal instructional resource and reference for students, research scientists, and professional engineers interested in analyzing fluid flows using numerical simulations for fundamental research and industrial applications. • Introduces CFD techniques for incompressible flow and turbulence with a comprehensive approach; • Enr...
A future for computational fluid dynamics at CERN
Battistin, M
2005-01-01
Computational Fluid Dynamics (CFD) is an analysis of fluid flow, heat transfer and associated phenomena in physical systems using computers. CFD has been used at CERN since 1993 by the TS-CV group, to solve thermo-fluid related problems, particularly during the development, design and construction phases of the LHC experiments. Computer models based on CFD techniques can be employed to reduce the effort required for prototype testing, saving not only time and money but offering possibilities of additional investigations and design optimisation. The development of a more efficient support team at CERN depends on to two important factors: available computing power and experienced engineers. Available computer power IS the limiting resource of CFD. Only the recent increase of computer power had allowed important high tech and industrial applications. Computer Grid is already now (OpenLab at CERN) and will be more so in the future natural environment for CFD science. At CERN, CFD activities have been developed by...
Application of a distributed network in computational fluid dynamic simulations
Deshpande, Manish; Feng, Jinzhang; Merkle, Charles L.; Deshpande, Ashish
1994-01-01
A general-purpose 3-D, incompressible Navier-Stokes algorithm is implemented on a network of concurrently operating workstations using parallel virtual machine (PVM) and compared with its performance on a CRAY Y-MP and on an Intel iPSC/860. The problem is relatively computationally intensive, and has a communication structure based primarily on nearest-neighbor communication, making it ideally suited to message passing. Such problems are frequently encountered in computational fluid dynamics (CDF), and their solution is increasingly in demand. The communication structure is explicitly coded in the implementation to fully exploit the regularity in message passing in order to produce a near-optimal solution. Results are presented for various grid sizes using up to eight processors.
Efficient Parallel Kernel Solvers for Computational Fluid Dynamics Applications
Sun, Xian-He
1997-01-01
Distributed-memory parallel computers dominate today's parallel computing arena. These machines, such as Intel Paragon, IBM SP2, and Cray Origin2OO, have successfully delivered high performance computing power for solving some of the so-called "grand-challenge" problems. Despite initial success, parallel machines have not been widely accepted in production engineering environments due to the complexity of parallel programming. On a parallel computing system, a task has to be partitioned and distributed appropriately among processors to reduce communication cost and to attain load balance. More importantly, even with careful partitioning and mapping, the performance of an algorithm may still be unsatisfactory, since conventional sequential algorithms may be serial in nature and may not be implemented efficiently on parallel machines. In many cases, new algorithms have to be introduced to increase parallel performance. In order to achieve optimal performance, in addition to partitioning and mapping, a careful performance study should be conducted for a given application to find a good algorithm-machine combination. This process, however, is usually painful and elusive. The goal of this project is to design and develop efficient parallel algorithms for highly accurate Computational Fluid Dynamics (CFD) simulations and other engineering applications. The work plan is 1) developing highly accurate parallel numerical algorithms, 2) conduct preliminary testing to verify the effectiveness and potential of these algorithms, 3) incorporate newly developed algorithms into actual simulation packages. The work plan has well achieved. Two highly accurate, efficient Poisson solvers have been developed and tested based on two different approaches: (1) Adopting a mathematical geometry which has a better capacity to describe the fluid, (2) Using compact scheme to gain high order accuracy in numerical discretization. The previously developed Parallel Diagonal Dominant (PDD) algorithm
Uncertainty quantification in computational fluid dynamics and aircraft engines
Montomoli, Francesco; D'Ammaro, Antonio; Massini, Michela; Salvadori, Simone
2015-01-01
This book introduces novel design techniques developed to increase the safety of aircraft engines. The authors demonstrate how the application of uncertainty methods can overcome problems in the accurate prediction of engine lift, caused by manufacturing error. This in turn ameliorates the difficulty of achieving required safety margins imposed by limits in current design and manufacturing methods. This text shows that even state-of-the-art computational fluid dynamics (CFD) are not able to predict the same performance measured in experiments; CFD methods assume idealised geometries but ideal geometries do not exist, cannot be manufactured and their performance differs from real-world ones. By applying geometrical variations of a few microns, the agreement with experiments improves dramatically, but unfortunately the manufacturing errors in engines or in experiments are unknown. In order to overcome this limitation, uncertainty quantification considers the probability density functions of manufacturing errors...
Computational thermal, chemical, fluid, and solid mechanics for geosystems management.
Energy Technology Data Exchange (ETDEWEB)
Davison, Scott; Alger, Nicholas; Turner, Daniel Zack; Subia, Samuel Ramirez; Carnes, Brian; Martinez, Mario J.; Notz, Patrick K.; Klise, Katherine A.; Stone, Charles Michael; Field, Richard V., Jr.; Newell, Pania; Jove-Colon, Carlos F.; Red-Horse, John Robert; Bishop, Joseph E.; Dewers, Thomas A.; Hopkins, Polly L.; Mesh, Mikhail; Bean, James E.; Moffat, Harry K.; Yoon, Hongkyu
2011-09-01
This document summarizes research performed under the SNL LDRD entitled - Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission. The main accomplishment was development of a foundational SNL capability for computational thermal, chemical, fluid, and solid mechanics analysis of geosystems. The code was developed within the SNL Sierra software system. This report summarizes the capabilities of the simulation code and the supporting research and development conducted under this LDRD. The main goal of this project was the development of a foundational capability for coupled thermal, hydrological, mechanical, chemical (THMC) simulation of heterogeneous geosystems utilizing massively parallel processing. To solve these complex issues, this project integrated research in numerical mathematics and algorithms for chemically reactive multiphase systems with computer science research in adaptive coupled solution control and framework architecture. This report summarizes and demonstrates the capabilities that were developed together with the supporting research underlying the models. Key accomplishments are: (1) General capability for modeling nonisothermal, multiphase, multicomponent flow in heterogeneous porous geologic materials; (2) General capability to model multiphase reactive transport of species in heterogeneous porous media; (3) Constitutive models for describing real, general geomaterials under multiphase conditions utilizing laboratory data; (4) General capability to couple nonisothermal reactive flow with geomechanics (THMC); (5) Phase behavior thermodynamics for the CO2-H2O-NaCl system. General implementation enables modeling of other fluid mixtures. Adaptive look-up tables enable thermodynamic capability to other simulators; (6) Capability for statistical modeling of heterogeneity in geologic materials; and (7) Simulator utilizes unstructured grids on parallel processing computers.
2014-08-01
Thiscorrection takes into account the velocity of neighboring mark-ers through a mean velocity evaluated within the support of anominal marker a as v̂a...right hand side of Eqs. (7) and (8), are accounted for,the total rigid body force and torque due to the interaction withthe fluid can be obtained by...absolute nodal coordinate formulation. In: Pro-ceedings of the ASME 2005 IDETC/ CIE , Orlando, FL, USA.American Society of Mechanical Engineers (2005)[35
Computational Biology and High Performance Computing 2000
Energy Technology Data Exchange (ETDEWEB)
Simon, Horst D.; Zorn, Manfred D.; Spengler, Sylvia J.; Shoichet, Brian K.; Stewart, Craig; Dubchak, Inna L.; Arkin, Adam P.
2000-10-19
The pace of extraordinary advances in molecular biology has accelerated in the past decade due in large part to discoveries coming from genome projects on human and model organisms. The advances in the genome project so far, happening well ahead of schedule and under budget, have exceeded any dreams by its protagonists, let alone formal expectations. Biologists expect the next phase of the genome project to be even more startling in terms of dramatic breakthroughs in our understanding of human biology, the biology of health and of disease. Only today can biologists begin to envision the necessary experimental, computational and theoretical steps necessary to exploit genome sequence information for its medical impact, its contribution to biotechnology and economic competitiveness, and its ultimate contribution to environmental quality. High performance computing has become one of the critical enabling technologies, which will help to translate this vision of future advances in biology into reality. Biologists are increasingly becoming aware of the potential of high performance computing. The goal of this tutorial is to introduce the exciting new developments in computational biology and genomics to the high performance computing community.
Prospects for Computational Fluid Dynamics in Room Air Contaminant Control
DEFF Research Database (Denmark)
Nielsen, Peter V.
The fluid dynamics research is strongly influenced by the increasing computer power which has been available for the last decades. This development is obvious from the curve in figure 1 which shows the computation cost as a function of years. It is obvious that the cost for a given job will decre...
Computational fluid dynamics simulations of light water reactor flows
International Nuclear Information System (INIS)
Tzanos, C.P.; Weber, D.P.
1999-01-01
Advances in computational fluid dynamics (CFD), turbulence simulation, and parallel computing have made feasible the development of three-dimensional (3-D) single-phase and two-phase flow CFD codes that can simulate fluid flow and heat transfer in realistic reactor geometries with significantly reduced reliance, especially in single phase, on empirical correlations. The objective of this work was to assess the predictive power and computational efficiency of a CFD code in the analysis of a challenging single-phase light water reactor problem, as well as to identify areas where further improvements are needed
An Introduction to Computational Fluid Mechanics by Example
Biringen, Sedat
2011-01-01
This new book builds on the original classic textbook entitled: An Introduction to Computational Fluid Mechanics by C. Y. Chow which was originally published in 1979. In the decades that have passed since this book was published the field of computational fluid dynamics has seen a number of changes in both the sophistication of the algorithms used but also advances in the computer hardware and software available. This new book incorporates the latest algorithms in the solution techniques and supports this by using numerous examples of applications to a broad range of industries from mechanical
Unsteady computational fluid dynamics in aeronautics
Tucker, P G
2014-01-01
The field of Large Eddy Simulation (LES) and hybrids is a vibrant research area. This book runs through all the potential unsteady modelling fidelity ranges, from low-order to LES. The latter is probably the highest fidelity for practical aerospace systems modelling. Cutting edge new frontiers are defined. One example of a pressing environmental concern is noise. For the accurate prediction of this, unsteady modelling is needed. Hence computational aeroacoustics is explored. It is also emerging that there is a critical need for coupled simulations. Hence, this area is also considered and the tensions of utilizing such simulations with the already expensive LES. This work has relevance to the general field of CFD and LES and to a wide variety of non-aerospace aerodynamic systems (e.g. cars, submarines, ships, electronics, buildings). Topics treated include unsteady flow techniques; LES and hybrids; general numerical methods; computational aeroacoustics; computational aeroelasticity; coupled simulations and...
Fluid dynamics parallel computer development at NASA Langley Research Center
Townsend, James C.; Zang, Thomas A.; Dwoyer, Douglas L.
1987-01-01
To accomplish more detailed simulations of highly complex flows, such as the transition to turbulence, fluid dynamics research requires computers much more powerful than any available today. Only parallel processing on multiple-processor computers offers hope for achieving the required effective speeds. Looking ahead to the use of these machines, the fluid dynamicist faces three issues: algorithm development for near-term parallel computers, architecture development for future computer power increases, and assessment of possible advantages of special purpose designs. Two projects at NASA Langley address these issues. Software development and algorithm exploration is being done on the FLEX/32 Parallel Processing Research Computer. New architecture features are being explored in the special purpose hardware design of the Navier-Stokes Computer. These projects are complementary and are producing promising results.
Computational Fluid Dynamics and Ventilation Airflow
DEFF Research Database (Denmark)
Nielsen, Peter Vilhelm
2014-01-01
the principle behind CFD, the development in numerical schemes and computer size since the 1970s. Special attention is given to the selection of the correct governing equations, to the understanding of low turbulent flow, to the selection of turbulence models, and to addressing situations with more steady...
Computational fluid dynamics (CFD) studies of a miniaturized dissolution system.
Frenning, G; Ahnfelt, E; Sjögren, E; Lennernäs, H
2017-04-15
Dissolution testing is an important tool that has applications ranging from fundamental studies of drug-release mechanisms to quality control of the final product. The rate of release of the drug from the delivery system is known to be affected by hydrodynamics. In this study we used computational fluid dynamics to simulate and investigate the hydrodynamics in a novel miniaturized dissolution method for parenteral formulations. The dissolution method is based on a rotating disc system and uses a rotating sample reservoir which is separated from the remaining dissolution medium by a nylon screen. Sample reservoirs of two sizes were investigated (SR6 and SR8) and the hydrodynamic studies were performed at rotation rates of 100, 200 and 400rpm. The overall fluid flow was similar for all investigated cases, with a lateral upward spiraling motion and central downward motion in the form of a vortex to and through the screen. The simulations indicated that the exchange of dissolution medium between the sample reservoir and the remaining release medium was rapid for typical screens, for which almost complete mixing would be expected to occur within less than one minute at 400rpm. The local hydrodynamic conditions in the sample reservoirs depended on their size; SR8 appeared to be relatively more affected than SR6 by the resistance to liquid flow resulting from the screen. Copyright © 2017 Elsevier B.V. All rights reserved.
Benchmarking Computational Fluid Dynamics for Application to PWR Fuel
International Nuclear Information System (INIS)
Smith, L.D. III; Conner, M.E.; Liu, B.; Dzodzo, B.; Paramonov, D.V.; Beasley, D.E.; Langford, H.M.; Holloway, M.V.
2002-01-01
The present study demonstrates a process used to develop confidence in Computational Fluid Dynamics (CFD) as a tool to investigate flow and temperature distributions in a PWR fuel bundle. The velocity and temperature fields produced by a mixing spacer grid of a PWR fuel assembly are quite complex. Before using CFD to evaluate these flow fields, a rigorous benchmarking effort should be performed to ensure that reasonable results are obtained. Westinghouse has developed a method to quantitatively benchmark CFD tools against data at conditions representative of the PWR. Several measurements in a 5 x 5 rod bundle were performed. Lateral flow-field testing employed visualization techniques and Particle Image Velocimetry (PIV). Heat transfer testing involved measurements of the single-phase heat transfer coefficient downstream of the spacer grid. These test results were used to compare with CFD predictions. Among the parameters optimized in the CFD models based on this comparison with data include computational mesh, turbulence model, and boundary conditions. As an outcome of this effort, a methodology was developed for CFD modeling that provides confidence in the numerical results. (authors)
Fluid dynamics applications of the Illiac IV computer
Maccormack, R. W.; Stevens, K. G., Jr.
1976-01-01
The Illiac IV is a parallel-structure computer with computing power an order of magnitude greater than that of conventional computers. It can be used for experimental tasks in fluid dynamics which can be simulated more economically, for simulating flows that cannot be studied by experiment, and for combining computer and experimental simulations. The architecture of Illiac IV is described, and the use of its parallel operation is demonstrated on the example of its solution of the one-dimensional wave equation. For fluid dynamics problems, a special FORTRAN-like vector programming language was devised, called CFD language. Two applications are described in detail: (1) the determination of the flowfield around the space shuttle, and (2) the computation of transonic turbulent separated flow past a thick biconvex airfoil.
Groves, Curtis Edward
2014-01-01
Spacecraft thermal protection systems are at risk of being damaged due to airflow produced from Environmental Control Systems. There are inherent uncertainties and errors associated with using Computational Fluid Dynamics to predict the airflow field around a spacecraft from the Environmental Control System. This paper describes an approach to quantify the uncertainty in using Computational Fluid Dynamics to predict airflow speeds around an encapsulated spacecraft without the use of test data. Quantifying the uncertainty in analytical predictions is imperative to the success of any simulation-based product. The method could provide an alternative to traditional "validation by test only" mentality. This method could be extended to other disciplines and has potential to provide uncertainty for any numerical simulation, thus lowering the cost of performing these verifications while increasing the confidence in those predictions. Spacecraft requirements can include a maximum airflow speed to protect delicate instruments during ground processing. Computational Fluid Dynamics can be used to verify these requirements; however, the model must be validated by test data. This research includes the following three objectives and methods. Objective one is develop, model, and perform a Computational Fluid Dynamics analysis of three (3) generic, non-proprietary, environmental control systems and spacecraft configurations. Several commercially available and open source solvers have the capability to model the turbulent, highly three-dimensional, incompressible flow regime. The proposed method uses FLUENT, STARCCM+, and OPENFOAM. Objective two is to perform an uncertainty analysis of the Computational Fluid Dynamics model using the methodology found in "Comprehensive Approach to Verification and Validation of Computational Fluid Dynamics Simulations". This method requires three separate grids and solutions, which quantify the error bars around Computational Fluid Dynamics
Groves, Curtis Edward
2014-01-01
Spacecraft thermal protection systems are at risk of being damaged due to airflow produced from Environmental Control Systems. There are inherent uncertainties and errors associated with using Computational Fluid Dynamics to predict the airflow field around a spacecraft from the Environmental Control System. This paper describes an approach to quantify the uncertainty in using Computational Fluid Dynamics to predict airflow speeds around an encapsulated spacecraft without the use of test data. Quantifying the uncertainty in analytical predictions is imperative to the success of any simulation-based product. The method could provide an alternative to traditional validation by test only mentality. This method could be extended to other disciplines and has potential to provide uncertainty for any numerical simulation, thus lowering the cost of performing these verifications while increasing the confidence in those predictions.Spacecraft requirements can include a maximum airflow speed to protect delicate instruments during ground processing. Computational Fluid Dynamics can be used to verify these requirements; however, the model must be validated by test data. This research includes the following three objectives and methods. Objective one is develop, model, and perform a Computational Fluid Dynamics analysis of three (3) generic, non-proprietary, environmental control systems and spacecraft configurations. Several commercially available and open source solvers have the capability to model the turbulent, highly three-dimensional, incompressible flow regime. The proposed method uses FLUENT, STARCCM+, and OPENFOAM. Objective two is to perform an uncertainty analysis of the Computational Fluid Dynamics model using the methodology found in Comprehensive Approach to Verification and Validation of Computational Fluid Dynamics Simulations. This method requires three separate grids and solutions, which quantify the error bars around Computational Fluid Dynamics predictions
Yang, Weiguang; Vignon-Clementel, Irene E; Troianowski, Guillaume; Reddy, V Mohan; Feinstein, Jeffrey A; Marsden, Alison L
2012-05-01
A novel Y-shaped baffle has been proposed for the Fontan operation with promising initial results. However, previous studies have relied either on idealized models or a single patient-specific model. The objective of this study is to comprehensively compare the hemodynamic performance and hepatic blood flow distribution of the Y-graft Fontan baffle with 2 current designs using multiple patient-specific models. Y-shaped and tube-shaped grafts were virtually implanted into 5 patient-specific Glenn models forming 3 types of Fontan geometries: Y-graft, T-junction, and offset. Unsteady flow simulations were performed at rest and at varying exercise conditions. The hepatic flow distribution between the right and left lungs was carefully quantified using a particle tracking method. Other physiologically relevant parameters such as energy dissipation, superior vena cava pressure, and wall shear stress were evaluated. The Fontan geometry significantly influences the hepatic flow distribution. The Y-graft design improves the hepatic flow distribution effectively in 4 of 5 patients, whereas the T-junction and offset designs may skew as much as 97% of hepatic flow to 1 lung in 2 cases. Sensitivity studies show that changes in pulmonary flow split can affect the hepatic flow distribution dramatically but that some Y-graft and T-junction designs are relatively less sensitive than offset designs. The Y-graft design offers moderate improvements over the traditional designs in power loss and superior vena cava pressure in all patients. The Y-graft Fontan design achieves overall superior hemodynamic performance compared with traditional designs. However, the results emphasize that no one-size-fits-all solution is available that will universally benefit all patients and that designs should be customized for individual patients before clinical application. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.
Computer simulations of a rough sphere fluid
International Nuclear Information System (INIS)
Lyklema, J.W.
1978-01-01
A computer simulation is described on rough hard spheres with a continuously variable roughness parameter, including the limits of smooth and completely rough spheres. A system of 500 particles is simulated with a homogeneous mass distribution at 8 different densities and for 5 different values of the roughness parameter. For these 40 physically different situations the intermediate scattering function for 6 values of the wave number, the orientational correlation functions and the velocity autocorrelation functions have been calculated. A comparison has been made with a neutron scattering experiment on neopentane and agreement was good for an intermediate value of the roughness parameter. Some often made approximations in neutron scattering experiments are also checked. The influence of the variable roughness parameter on the correlation functions has been investigated and three simple stochastic models studied to describe the orientational correlation function which shows the most pronounced dependence on the roughness. (Auth.)
Computer-Related Task Performance
DEFF Research Database (Denmark)
Longstreet, Phil; Xiao, Xiao; Sarker, Saonee
2016-01-01
The existing information system (IS) literature has acknowledged computer self-efficacy (CSE) as an important factor contributing to enhancements in computer-related task performance. However, the empirical results of CSE on performance have not always been consistent, and increasing an individual......'s CSE is often a cumbersome process. Thus, we introduce the theoretical concept of self-prophecy (SP) and examine how this social influence strategy can be used to improve computer-related task performance. Two experiments are conducted to examine the influence of SP on task performance. Results show...... that SP and CSE interact to influence performance. Implications are then discussed in terms of organizations’ ability to increase performance....
Computational fluid dynamics on a massively parallel computer
Jespersen, Dennis C.; Levit, Creon
1989-01-01
A finite difference code was implemented for the compressible Navier-Stokes equations on the Connection Machine, a massively parallel computer. The code is based on the ARC2D/ARC3D program and uses the implicit factored algorithm of Beam and Warming. The codes uses odd-even elimination to solve linear systems. Timings and computation rates are given for the code, and a comparison is made with a Cray XMP.
Class of reconstructed discontinuous Galerkin methods in computational fluid dynamics
International Nuclear Information System (INIS)
Luo, Hong; Xia, Yidong; Nourgaliev, Robert
2011-01-01
A class of reconstructed discontinuous Galerkin (DG) methods is presented to solve compressible flow problems on arbitrary grids. The idea is to combine the efficiency of the reconstruction methods in finite volume methods and the accuracy of the DG methods to obtain a better numerical algorithm in computational fluid dynamics. The beauty of the resulting reconstructed discontinuous Galerkin (RDG) methods is that they provide a unified formulation for both finite volume and DG methods, and contain both classical finite volume and standard DG methods as two special cases of the RDG methods, and thus allow for a direct efficiency comparison. Both Green-Gauss and least-squares reconstruction methods and a least-squares recovery method are presented to obtain a quadratic polynomial representation of the underlying linear discontinuous Galerkin solution on each cell via a so-called in-cell reconstruction process. The devised in-cell reconstruction is aimed to augment the accuracy of the discontinuous Galerkin method by increasing the order of the underlying polynomial solution. These three reconstructed discontinuous Galerkin methods are used to compute a variety of compressible flow problems on arbitrary meshes to assess their accuracy. The numerical experiments demonstrate that all three reconstructed discontinuous Galerkin methods can significantly improve the accuracy of the underlying second-order DG method, although the least-squares reconstructed DG method provides the best performance in terms of both accuracy, efficiency, and robustness. (author)
Algorithms for computational fluid dynamics n parallel processors
International Nuclear Information System (INIS)
Van de Velde, E.F.
1986-01-01
A study of parallel algorithms for the numerical solution of partial differential equations arising in computational fluid dynamics is presented. The actual implementation on parallel processors of shared and nonshared memory design is discussed. The performance of these algorithms is analyzed in terms of machine efficiency, communication time, bottlenecks and software development costs. For elliptic equations, a parallel preconditioned conjugate gradient method is described, which has been used to solve pressure equations discretized with high order finite elements on irregular grids. A parallel full multigrid method and a parallel fast Poisson solver are also presented. Hyperbolic conservation laws were discretized with parallel versions of finite difference methods like the Lax-Wendroff scheme and with the Random Choice method. Techniques are developed for comparing the behavior of an algorithm on different architectures as a function of problem size and local computational effort. Effective use of these advanced architecture machines requires the use of machine dependent programming. It is shown that the portability problems can be minimized by introducing high level operations on vectors and matrices structured into program libraries
Computational Fluid and Particle Dynamics in the Human Respiratory System
Tu, Jiyuan; Ahmadi, Goodarz
2013-01-01
Traditional research methodologies in the human respiratory system have always been challenging due to their invasive nature. Recent advances in medical imaging and computational fluid dynamics (CFD) have accelerated this research. This book compiles and details recent advances in the modelling of the respiratory system for researchers, engineers, scientists, and health practitioners. It breaks down the complexities of this field and provides both students and scientists with an introduction and starting point to the physiology of the respiratory system, fluid dynamics and advanced CFD modeling tools. In addition to a brief introduction to the physics of the respiratory system and an overview of computational methods, the book contains best-practice guidelines for establishing high-quality computational models and simulations. Inspiration for new simulations can be gained through innovative case studies as well as hands-on practice using pre-made computational code. Last but not least, students and researcher...
Unsteady computational fluid dynamics in front crawl swimming.
Samson, Mathias; Bernard, Anthony; Monnet, Tony; Lacouture, Patrick; David, Laurent
2017-05-01
The development of codes and power calculations currently allows the simulation of increasingly complex flows, especially in the turbulent regime. Swimming research should benefit from these technological advances to try to better understand the dynamic mechanisms involved in swimming. An unsteady Computational Fluid Dynamics (CFD) study is conducted in crawl, in order to analyse the propulsive forces generated by the hand and forearm. The k-ω SST turbulence model and an overset grid method have been used. The main objectives are to analyse the evolution of the hand-forearm propulsive forces and to explain this relative to the arm kinematics parameters. In order to validate our simulation model, the calculated forces and pressures were compared with several other experimental and numerical studies. A good agreement is found between our results and those of other studies. The hand is the segment that generates the most propulsive forces during the aquatic stroke. As the pressure component is the main source of force, the orientation of the hand-forearm in the absolute coordinate system is an important kinematic parameter in the swimming performance. The propulsive forces are biggest when the angles of attack are high. CFD appears as a very valuable tool to better analyze the mechanisms of swimming performance and offers some promising developments, especially for optimizing the performance from a parametric study.
Computational fluid dynamics modelling of displacement natural ventilation.
Ji, Yingchun
2005-01-01
Natural ventilation is widely recognised as contributing towards low-energy building design. The requirement to reduce energy usage in new buildings has rejuvenated interest in natural ventilation. This thesis deals with computer modelling of natural displacement ventilation driven either by buoyancy or buoyancy combined with wind forces. Two benchmarks have been developed using computational fluid dynamics (CFD) in order to evaluate the accuracy with which CFD is able to mo...
Directory of Open Access Journals (Sweden)
Yonghui Xie
2014-01-01
Full Text Available A three-dimensional fluid-thermal-structural coupled analysis for a radial inflow micro gas turbine is conducted. First, a fluid-thermal coupled analysis of the flow and temperature fields of the nozzle passage and the blade passage is performed by using computational fluid dynamics (CFD. The flow and heat transfer characteristics of different sections are analyzed in detail. The thermal load and the aerodynamic load are then obtained from the temperature field and the pressure distribution. The stress distributions of the blade are finally studied by using computational solid mechanics (CSM considering three cases of loads: thermal load, aerodynamics load combined with centrifugal load, and all the three types of loads. The detailed parameters of the flow, temperature, and the stress are obtained and analyzed. The numerical results obtained provide a useful knowledge base for further exploration of radial gas turbine design.
Computational Fluid Dynamics of Two MBR Configurations
DEFF Research Database (Denmark)
Bentzen, Thomas Ruby; Ratkovich, Nicolas Rios; Rasmussen, Michael R.
2011-01-01
made for both systems and compared to CFD results. In general there was found a good agreement between experimental measurements and CFD results (error less than 20 %). Due to the fact the shear stress measurements were not perform, they were extracted from the CFD simulations, as the CFD simulation...... was validated against velocity data. The results of shear stress shows that the RCF system has larger (up to 10 times) shear values compared to hollow sheet (HS) systems. However, the shear stress in the RCF system is not homogeneously distributes, as for the HS system....
Modelling Emission from Building Materials with Computational Fluid Dynamics
DEFF Research Database (Denmark)
Topp, Claus; Nielsen, Peter V.; Heiselberg, Per
This paper presents a numerical model that by means of computational fluid dynamics (CFD) is capable of dealing with both pollutant transport across the boundary layer and internal diffusion in the source without prior knowledge of which is the limiting process. The model provides the concentration...
Computer program for calculating thermodynamic and transport properties of fluids
Hendricks, R. C.; Braon, A. K.; Peller, I. C.
1975-01-01
Computer code has been developed to provide thermodynamic and transport properties of liquid argon, carbon dioxide, carbon monoxide, fluorine, helium, methane, neon, nitrogen, oxygen, and parahydrogen. Equation of state and transport coefficients are updated and other fluids added as new material becomes available.
On Computational Fluid Dynamics Tools in Architectural Design
DEFF Research Database (Denmark)
Kirkegaard, Poul Henning; Hougaard, Mads; Stærdahl, Jesper Winther
engineering computational fluid dynamics (CFD) simulation program ANSYS CFX and a CFD based representative program RealFlow are investigated. These two programs represent two types of CFD based tools available for use during phases of an architectural design process. However, as outlined in two case studies...
HAMOC: a computer program for fluid hammer analysis
International Nuclear Information System (INIS)
Johnson, H.G.
1975-12-01
A computer program has been developed for fluid hammer analysis of piping systems attached to a vessel which has undergone a known rapid pressure transient. The program is based on the characteristics method for solution of the partial differential equations of motion and continuity. Column separation logic is included for situations in which pressures fall to saturation values
Multiscale methods in computational fluid and solid mechanics
Borst, de R.; Hulshoff, S.J.; Lenz, S.; Munts, E.A.; Brummelen, van E.H.; Wall, W.; Wesseling, P.; Onate, E.; Periaux, J.
2006-01-01
First, an attempt is made towards gaining a more systematic understanding of recent progress in multiscale modelling in computational solid and fluid mechanics. Sub- sequently, the discussion is focused on variational multiscale methods for the compressible and incompressible Navier-Stokes
Advances in Computational Fluid-Structure Interaction and Flow Simulation Conference
Takizawa, Kenji
2016-01-01
This contributed volume celebrates the work of Tayfun E. Tezduyar on the occasion of his 60th birthday. The articles it contains were born out of the Advances in Computational Fluid-Structure Interaction and Flow Simulation (AFSI 2014) conference, also dedicated to Prof. Tezduyar and held at Waseda University in Tokyo, Japan on March 19-21, 2014. The contributing authors represent a group of international experts in the field who discuss recent trends and new directions in computational fluid dynamics (CFD) and fluid-structure interaction (FSI). Organized into seven distinct parts arranged by thematic topics, the papers included cover basic methods and applications of CFD, flows with moving boundaries and interfaces, phase-field modeling, computer science and high-performance computing (HPC) aspects of flow simulation, mathematical methods, biomedical applications, and FSI. Researchers, practitioners, and advanced graduate students working on CFD, FSI, and related topics will find this collection to be a defi...
Correlation of cutting fluid performance in different machining operations
DEFF Research Database (Denmark)
De Chiffre, Leonardo; Belluco, Walter
2001-01-01
An analysis of cutting fluid performance in different metal cutting operations is presented, based on experimental investigations in which type of operation, performance criteria, work material, and fluid type are considered. Cutting fluid performance was evaluated in turning, drilling, reaming...... investigated. Results show that correlation of cutting fluid performance in different operations exists, within the same group of cutting fluids, in the case of stainless steel as workpiece material. Under the tested conditions, the average correlation coefficients between efficiency parameters with different...... operations on austenitic stainless steel lied in the range 0.87-0.97 for waterbased fluids and 0.79-0.89 for straight oils. A similar correlation could not be found for the other workpiece materials investigated in this work. A rationalisation of cutting fluid performance tests is suggested....
Computational Fluid Dynamics Analysis of Flexible Duct Junction Box Design
Energy Technology Data Exchange (ETDEWEB)
Beach, Robert [IBACOS Inc., Pittsburgh, PA (United States); Prahl, Duncan [IBACOS Inc., Pittsburgh, PA (United States); Lange, Rich [IBACOS Inc., Pittsburgh, PA (United States)
2013-12-01
IBACOS explored the relationships between pressure and physical configurations of flexible duct junction boxes by using computational fluid dynamics (CFD) simulations to predict individual box parameters and total system pressure, thereby ensuring improved HVAC performance. Current Air Conditioning Contractors of America (ACCA) guidance (Group 11, Appendix 3, ACCA Manual D, Rutkowski 2009) allows for unconstrained variation in the number of takeoffs, box sizes, and takeoff locations. The only variables currently used in selecting an equivalent length (EL) are velocity of air in the duct and friction rate, given the first takeoff is located at least twice its diameter away from the inlet. This condition does not account for other factors impacting pressure loss across these types of fittings. For each simulation, the IBACOS team converted pressure loss within a box to an EL to compare variation in ACCA Manual D guidance to the simulated variation. IBACOS chose cases to represent flows reasonably correlating to flows typically encountered in the field and analyzed differences in total pressure due to increases in number and location of takeoffs, box dimensions, and velocity of air, and whether an entrance fitting is included. The team also calculated additional balancing losses for all cases due to discrepancies between intended outlet flows and natural flow splits created by the fitting. In certain asymmetrical cases, the balancing losses were significantly higher than symmetrical cases where the natural splits were close to the targets. Thus, IBACOS has shown additional design constraints that can ensure better system performance.
Morphing-Based Shape Optimization in Computational Fluid Dynamics
Rousseau, Yannick; Men'Shov, Igor; Nakamura, Yoshiaki
In this paper, a Morphing-based Shape Optimization (MbSO) technique is presented for solving Optimum-Shape Design (OSD) problems in Computational Fluid Dynamics (CFD). The proposed method couples Free-Form Deformation (FFD) and Evolutionary Computation, and, as its name suggests, relies on the morphing of shape and computational domain, rather than direct shape parameterization. Advantages of the FFD approach compared to traditional parameterization are first discussed. Then, examples of shape and grid deformations by FFD are presented. Finally, the MbSO approach is illustrated and applied through an example: the design of an airfoil for a future Mars exploration airplane.
On the Use of Computers for Teaching Fluid Mechanics
Benson, Thomas J.
1994-01-01
Several approaches for improving the teaching of basic fluid mechanics using computers are presented. There are two objectives to these approaches: to increase the involvement of the student in the learning process and to present information to the student in a variety of forms. Items discussed include: the preparation of educational videos using the results of computational fluid dynamics (CFD) calculations, the analysis of CFD flow solutions using workstation based post-processing graphics packages, and the development of workstation or personal computer based simulators which behave like desk top wind tunnels. Examples of these approaches are presented along with observations from working with undergraduate co-ops. Possible problems in the implementation of these approaches as well as solutions to these problems are also discussed.
The coupling of fluids, dynamics, and controls on advanced architecture computers
Atwood, Christopher
1995-01-01
This grant provided for the demonstration of coupled controls, body dynamics, and fluids computations in a workstation cluster environment; and an investigation of the impact of peer-peer communication on flow solver performance and robustness. The findings of these investigations were documented in the conference articles.The attached publication, 'Towards Distributed Fluids/Controls Simulations', documents the solution and scaling of the coupled Navier-Stokes, Euler rigid-body dynamics, and state feedback control equations for a two-dimensional canard-wing. The poor scaling shown was due to serialized grid connectivity computation and Ethernet bandwidth limits. The scaling of a peer-to-peer communication flow code on an IBM SP-2 was also shown. The scaling of the code on the switched fabric-linked nodes was good, with a 2.4 percent loss due to communication of intergrid boundary point information. The code performance on 30 worker nodes was 1.7 (mu)s/point/iteration, or a factor of three over a Cray C-90 head. The attached paper, 'Nonlinear Fluid Computations in a Distributed Environment', documents the effect of several computational rate enhancing methods on convergence. For the cases shown, the highest throughput was achieved using boundary updates at each step, with the manager process performing communication tasks only. Constrained domain decomposition of the implicit fluid equations did not degrade the convergence rate or final solution. The scaling of a coupled body/fluid dynamics problem on an Ethernet-linked cluster was also shown.
Tjahjana, Dominicus Danardono Dwi Prija; Purbaningrum, Pradityasari; Hadi, Syamsul; Wicaksono, Yoga Arob; Adiputra, Dimas
2018-02-01
Cross flow turbine can be one of the alternative energies for regions with low wind speed. Collision between wind and the blades which happened two times caused the cross flow turbine to have high power coefficient. Some factors that influence the turbine power coefficient are diameter ratio and blade number. The objective of the research was to study the effect of the diameter ratio and the blade number to the cross flow wind turbine performance. The study was done in two dimensional (2D) computational fluid dynamics (CFD) simulation method using the ANSYS-Fluent software. The turbine diameter ratio were 0.58, 0.63, 0.68 and 0.73. The diameter ratio resulting in the highest power coefficient value was then simulated by varying the number of blades, namely 16, 20 and 24. Each variation was tested on the wind speed of 2 m/s and at the tip speed ratio (TSR) of 0.1 to 0.4 with the interval of 0.1. The wind turbine with the ratio diameter of 0.68 and the number of blades of 20 generated the highest power coefficient of 0.5 at the TSR of 0.3.
Evidence of nonuniqueness and oscillatory solutions in computational fluid mechanics
International Nuclear Information System (INIS)
Nunziato, J.W.; Gartling, D.K.; Kipp, M.E.
1985-01-01
We will review some of our recent experiences in computing solutions for nonlinear fluids in relatively simple, two-dimensional geometries. The purpose of this discussion will be to display by example some of the interesting but difficult questions that arise when ill-behaved solutions are obtained numerically. We will consider two examples. As the first example, we will consider a nonlinear elastic (compressible) fluid with chemical reactions and discuss solutions for detonation and detonation failure in a two-dimensional cylinder. In this case, the numerical algorithm utilizes a finite-difference method with artificial viscosity (von Neumann-Richtmyer method) and leads to two, distinctly different, stable solutions depending on the time step criterion used. The second example to be considered involves the convection of a viscous fluid in a rectangular container as a result of an exothermic polymerization reaction. A solidification front develops near the top of the container and propagates down through the fluid, changing the aspect ratio of the region ahead of the front. Using a Galerkin-based finite element method, a numerical solution of the partial differential equations is obtained which tracks the front and correctly predicts the fluid temperatures near the walls. However, the solution also exhibits oscillatory behavior with regard to the number of cells in the fluid ahead of the front and in the strength of the cells. More definitive experiments and analysis are required to determine whether this oscillatory phenomena is a numerical artifact or a physical reality. 20 refs., 14 figs
Application of computational fluid mechanics to atmospheric pollution problems
Hung, R. J.; Liaw, G. S.; Smith, R. E.
1986-01-01
One of the most noticeable effects of air pollution on the properties of the atmosphere is the reduction in visibility. This paper reports the results of investigations of the fluid dynamical and microphysical processes involved in the formation of advection fog on aerosols from combustion-related pollutants, as condensation nuclei. The effects of a polydisperse aerosol distribution, on the condensation/nucleation processes which cause the reduction in visibility are studied. This study demonstrates how computational fluid mechanics and heat transfer modeling can be applied to simulate the life cycle of the atmosphereic pollution problems.
Using artificial intelligence to control fluid flow computations
Gelsey, Andrew
1992-01-01
Computational simulation is an essential tool for the prediction of fluid flow. Many powerful simulation programs exist today. However, using these programs to reliably analyze fluid flow and other physical situations requires considerable human effort and expertise to set up a simulation, determine whether the output makes sense, and repeatedly run the simulation with different inputs until a satisfactory result is achieved. Automating this process is not only of considerable practical importance but will also significantly advance basic artificial intelligence (AI) research in reasoning about the physical world.
Symposium on computational fluid dynamics: technology and applications
International Nuclear Information System (INIS)
1988-01-01
A symposium on the technology and applications of computational fluid dynamics (CFD) was held in Pretoria from 21-23 Nov 1988. The following aspects were covered: multilevel adaptive methods and multigrid solvers in CFD, a symbolic processing approach to CFD, interplay between CFD and analytical approximations, CFD on a transfer array, the application of CFD in high speed aerodynamics, numerical simulation of laminar blood flow, two-phase flow modelling in nuclear accident analysis, and the finite difference scheme for the numerical solution of fluid flow
Optimizing drilling performance using a selected drilling fluid
Judzis, Arnis [Salt Lake City, UT; Black, Alan D [Coral Springs, FL; Green, Sidney J [Salt Lake City, UT; Robertson, Homer A [West Jordan, UT; Bland, Ronald G [Houston, TX; Curry, David Alexander [The Woodlands, TX; Ledgerwood, III, Leroy W.
2011-04-19
To improve drilling performance, a drilling fluid is selected based on one or more criteria and to have at least one target characteristic. Drilling equipment is used to drill a wellbore, and the selected drilling fluid is provided into the wellbore during drilling with the drilling equipment. The at least one target characteristic of the drilling fluid includes an ability of the drilling fluid to penetrate into formation cuttings during drilling to weaken the formation cuttings.
Performance Comparison and Selection of Transformer Fluid
Directory of Open Access Journals (Sweden)
Lu Yang
2016-01-01
Full Text Available Transformer fluid directly affects the working state of the components and the cooling efficiency of transformer. There are three kinds of transformer fluid used for electric locomotive, EMU and suburban rail vehicles: mineral oil, silicone liquid and synthetic ester based insulating oil. In this paper, the three kinds of oil are compared from the fire safety, environmental protection, reliability and low maintenance. It provides a strong basis for the selection of transformer fluid. By comprehensive analysis, synthetic ester based insulating oil can completely replace mineral oil and silicone liquid. With rail transport safety and environmental protection standards improving, synthetic ester based insulating oil will be the best choice for transformer.
Computer program for computing the properties of seventeen fluids. [cryogenic liquids
Brennan, J. A.; Friend, D. G.; Arp, V. D.; Mccarty, R. D.
1992-01-01
The present study describes modifications and additions to the MIPROPS computer program for calculating the thermophysical properties of 17 fluids. These changes include adding new fluids, new properties, and a new interface to the program. The new program allows the user to select the input and output parameters and the units to be displayed for each parameter. Fluids added to the MIPROPS program are carbon dioxide, carbon monoxide, deuterium, helium, normal hydrogen, and xenon. The most recent modifications to the MIPROPS program are the addition of viscosity and thermal conductivity correlations for parahydrogen and the addition of the fluids normal hydrogen and xenon. The recently added interface considerably increases the program's utility.
Performance analysis of organic Rankine cycles using different working fluids
Directory of Open Access Journals (Sweden)
Zhu Qidi
2015-01-01
Full Text Available Low-grade heat from renewable or waste energy sources can be effectively recovered to generate power by an organic Rankine cycle (ORC in which the working fluid has an important impact on its performance. The thermodynamic processes of ORCs using different types of organic fluids were analyzed in this paper. The relationships between the ORC’s performance parameters (including evaporation pressure, condensing pressure, outlet temperature of hot fluid, net power, thermal efficiency, exergy efficiency, total cycle irreversible loss, and total heat-recovery efficiency and the critical temperatures of organic fluids were established based on the property of the hot fluid through the evaporator in a specific working condition, and then were verified at varied evaporation temperatures and inlet temperatures of the hot fluid. Here we find that the performance parameters vary monotonically with the critical temperatures of organic fluids. The values of the performance parameters of the ORC using wet fluids are distributed more dispersedly with the critical temperatures, compared with those of using dry/isentropic fluids. The inlet temperature of the hot fluid affects the relative distribution of the exergy efficiency, whereas the evaporation temperature only has an impact on the performance parameters using wet fluid.
Experimental and computational fluid dynamics studies of mixing of complex oral health products
Cortada-Garcia, Marti; Migliozzi, Simona; Weheliye, Weheliye Hashi; Dore, Valentina; Mazzei, Luca; Angeli, Panagiota; ThAMes Multiphase Team
2017-11-01
Highly viscous non-Newtonian fluids are largely used in the manufacturing of specialized oral care products. Mixing often takes place in mechanically stirred vessels where the flow fields and mixing times depend on the geometric configuration and the fluid physical properties. In this research, we study the mixing performance of complex non-Newtonian fluids using Computational Fluid Dynamics models and validate them against experimental laser-based optical techniques. To this aim, we developed a scaled-down version of an industrial mixer. As test fluids, we used mixtures of glycerol and a Carbomer gel. The viscosities of the mixtures against shear rate at different temperatures and phase ratios were measured and found to be well described by the Carreau model. The numerical results were compared against experimental measurements of velocity fields from Particle Image Velocimetry (PIV) and concentration profiles from Planar Laser Induced Fluorescence (PLIF).
Design of airborne wind turbine and computational fluid dynamics analysis
Anbreen, Faiqa
Wind energy is a promising alternative to the depleting non-renewable sources. The height of the wind turbines becomes a constraint to their efficiency. Airborne wind turbine can reach much higher altitudes and produce higher power due to high wind velocity and energy density. The focus of this thesis is to design a shrouded airborne wind turbine, capable to generate 70 kW to propel a leisure boat with a capacity of 8-10 passengers. The idea of designing an airborne turbine is to take the advantage of higher velocities in the atmosphere. The Solidworks model has been analyzed numerically using Computational Fluid Dynamics (CFD) software StarCCM+. The Unsteady Reynolds Averaged Navier Stokes Simulation (URANS) with K-epsilon turbulence model has been selected, to study the physical properties of the flow, with emphasis on the performance of the turbine and the increase in air velocity at the throat. The analysis has been done using two ambient velocities of 12 m/s and 6 m/s. At 12 m/s inlet velocity, the velocity of air at the turbine has been recorded as 16 m/s. The power generated by the turbine is 61 kW. At inlet velocity of 6 m/s, the velocity of air at turbine increased to 10 m/s. The power generated by turbine is 25 kW.
Computational fluid dynamics for turbomachinery internal air systems.
Chew, John W; Hills, Nicholas J
2007-10-15
Considerable progress in development and application of computational fluid dynamics (CFD) for aeroengine internal flow systems has been made in recent years. CFD is regularly used in industry for assessment of air systems, and the performance of CFD for basic axisymmetric rotor/rotor and stator/rotor disc cavities with radial throughflow is largely understood and documented. Incorporation of three-dimensional geometrical features and calculation of unsteady flows are becoming commonplace. Automation of CFD, coupling with thermal models of the solid components, and extension of CFD models to include both air system and main gas path flows are current areas of development. CFD is also being used as a research tool to investigate a number of flow phenomena that are not yet fully understood. These include buoyancy-affected flows in rotating cavities, rim seal flows and mixed air/oil flows. Large eddy simulation has shown considerable promise for the buoyancy-driven flows and its use for air system flows is expected to expand in the future.
A computational model for doctoring fluid films in gravure printing
Energy Technology Data Exchange (ETDEWEB)
Hariprasad, Daniel S., E-mail: dshari@unm.edu [Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Grau, Gerd [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California 94720-1770 (United States); Schunk, P. Randall [Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, New Mexico 87185-0826 (United States); Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Tjiptowidjojo, Kristianto [Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States)
2016-04-07
The wiping, or doctoring, process in gravure printing presents a fundamental barrier to resolving the micron-sized features desired in printed electronics applications. This barrier starts with the residual fluid film left behind after wiping, and its importance grows as feature sizes are reduced, especially as the feature size approaches the thickness of the residual fluid film. In this work, various mechanical complexities are considered in a computational model developed to predict the residual fluid film thickness. Lubrication models alone are inadequate, and deformation of the doctor blade body together with elastohydrodynamic lubrication must be considered to make the model predictive of experimental trends. Moreover, model results demonstrate that the particular form of the wetted region of the blade has a significant impact on the model's ability to reproduce experimental measurements.
Investigations of Cutting Fluid Performance Using Different Machining Operations
DEFF Research Database (Denmark)
De Chiffre, Leonardo; Belluco, Walter
2002-01-01
An analysis of cutting fluid performance in dif-ferent metal cutting operations is presented based on performance criteria, work material and fluid type. Cutting fluid performance was evaluated in turning, drilling, reaming and tapping operations, with respect to tool life, cutting forces and prod...... will get the same performance ranking for different metalworking fluids no matter what machining test is used, when the fluids are of the same type. Results show that this is mostly true for the water-based fluids on austenitic stainless steel while ranking did change depending on the test with straight......-gated. In the case of austenitic stainless steel as the workpiece material, results using the different operations under different cutting conditions show that the performance of vegetable oil based prod-ucts is superior or equal to that of mineral oil based products. The hypothesis was investigated that one...
Three-dimensional Computational Fluid Dynamics Investigation of a Spinning Helicopter Slung Load
Theorn, J. N.; Duque, E. P. N.; Cicolani, L.; Halsey, R.
2005-01-01
After performing steady-state Computational Fluid Dynamics (CFD) calculations using OVERFLOW to validate the CFD method against static wind-tunnel data of a box-shaped cargo container, the same setup was used to investigate unsteady flow with a moving body. Results were compared to flight test data previously collected in which the container is spinning.
Simultaneous fluid-flow, heat-transfer and solid-stress computation in a single computer code
Energy Technology Data Exchange (ETDEWEB)
Spalding, D B [Concentration Heat and Momentum Ltd, London (United Kingdom)
1998-12-31
Computer simulation of flow- and thermally-induced stresses in mechanical-equipment assemblies has, in the past, required the use of two distinct software packages, one to determine the forces and the temperatures, and the other to compute the resultant stresses. The present paper describes how a single computer program can perform both tasks at the same time. The technique relies on the similarity of the equations governing velocity distributions in fluids to those governing displacements in solids. The same SIMPLE-like algorithm is used for solving both. Applications to 1-, 2- and 3-dimensional situations are presented. It is further suggested that Solid-Fluid-Thermal, ie SFT analysis may come to replace CFD on the one hand and the analysis of stresses in solids on the other, by performing the functions of both. (author) 7 refs.
Simultaneous fluid-flow, heat-transfer and solid-stress computation in a single computer code
Energy Technology Data Exchange (ETDEWEB)
Spalding, D.B. [Concentration Heat and Momentum Ltd, London (United Kingdom)
1997-12-31
Computer simulation of flow- and thermally-induced stresses in mechanical-equipment assemblies has, in the past, required the use of two distinct software packages, one to determine the forces and the temperatures, and the other to compute the resultant stresses. The present paper describes how a single computer program can perform both tasks at the same time. The technique relies on the similarity of the equations governing velocity distributions in fluids to those governing displacements in solids. The same SIMPLE-like algorithm is used for solving both. Applications to 1-, 2- and 3-dimensional situations are presented. It is further suggested that Solid-Fluid-Thermal, ie SFT analysis may come to replace CFD on the one hand and the analysis of stresses in solids on the other, by performing the functions of both. (author) 7 refs.
Fast reactor safety and computational thermo-fluid dynamics approaches
International Nuclear Information System (INIS)
Ninokata, Hisashi; Shimizu, Takeshi
1993-01-01
This article provides a brief description of the safety principle on which liquid metal cooled fast breeder reactors (LMFBRs) is based and the roles of computations in the safety practices. A number of thermohydraulics models have been developed to date that successfully describe several of the important types of fluids and materials motion encountered in the analysis of postulated accidents in LMFBRs. Most of these models use a mixture of implicit and explicit numerical solution techniques in solving a set of conservation equations formulated in Eulerian coordinates, with special techniques included to specific situations. Typical computational thermo-fluid dynamics approaches are discussed in particular areas of analyses of the physical phenomena relevant to the fuel subassembly thermohydraulics design and that involve describing the motion of molten materials in the core over a large scale. (orig.)
A computational fluid dynamics algorithm on a massively parallel computer
International Nuclear Information System (INIS)
Jespersen, D.C.; Levit, C.
1989-01-01
The implementation and performance of a finite-difference algorithm for the compressible Navier-Stokes equations in two or three dimensions on the Connection Machine are described. This machine is a single-instruction multiple-data machine with up to 65536 physical processors. The implicit portion of the algorithm is of particular interest. Running times and megadrop rates are given for two- and three-dimensional problems. Included are comparisons with the standard codes on a Cray X-MP/48. 15 refs
Tang, Z. B.; Deng, Y. D.; Su, C. Q.; Yuan, X. H.
2015-06-01
In this study, a numerical model has been employed to analyze the internal flow field distribution in a heat exchanger applied for an automotive thermoelectric generator based on computational fluid dynamics. The model simulates the influence of factors relevant to the heat exchanger, including the automotive waste heat mass flow velocity, temperature, internal fins, and back pressure. The result is in good agreement with experimental test data. Sensitivity analysis of the inlet parameters shows that increase of the exhaust velocity, compared with the inlet temperature, makes little contribution (0.1 versus 0.19) to the heat transfer but results in a detrimental back pressure increase (0.69 versus 0.21). A configuration equipped with internal fins is proved to offer better thermal performance compared with that without fins. Finally, based on an attempt to improve the internal flow field, a more rational structure is obtained, offering a more homogeneous temperature distribution, higher average heat transfer coefficient, and lower back pressure.
Quality control of computational fluid dynamics in indoor environments
DEFF Research Database (Denmark)
Sørensen, Dan Nørtoft; Nielsen, P. V.
2003-01-01
Computational fluid dynamics (CFD) is used routinely to predict air movement and distributions of temperature and concentrations in indoor environments. Modelling and numerical errors are inherent in such studies and must be considered when the results are presented. Here, we discuss modelling as...... the quality of CFD calculations, as well as guidelines for the minimum information that should accompany all CFD-related publications to enable a scientific judgment of the quality of the study....
Tactic-specific differences in seminal fluid influence sperm performance.
Locatello, Lisa; Poli, Federica; Rasotto, Maria B
2013-03-22
Seminal fluid often makes up a large part of an ejaculate, yet most empirical and theoretical studies on sperm competition have focused on how sperm characteristics (number and quality) affect fertilization success. However, seminal fluid influences own sperm performance and may potentially influence the outcome of sperm competition, by also affecting that of rivals. As a consequence males may be expected to allocate their investment in both sperm and seminal fluid in relation to the potential level of competition. Grass goby (Zosterisessor ophiocephalus) is an external fertilizer with guard-sneaker mating tactics, where sperm competition risk varies according to the tactic adopted. Here, we experimentally manipulated grass goby ejaculates by separately combining sperm and seminal fluid from territorial and sneaker males. While sperm of sneaker and territorial males did not differ in their performance when they interacted with their own seminal fluid only, sperm of sneakers increased their velocity and fertilization rate in the presence of territorial males' seminal fluid. By contrast, sneaker males' seminal fluid had a detrimental effect on the performance of territorial males' sperm. Sperm velocity was unaffected by the seminal fluid of males employing the same tactic, suggesting that seminal fluid's effect on rival-tactic sperm is not based on a self/non-self recognition mechanism. Our findings show that cross interactions of sperm and seminal fluid may influence the fertilization success of competing ejaculates with males investing in both sperm and seminal fluid in response to sperm competition risk.
Computer methods for transient fluid-structure analysis of nuclear reactors
International Nuclear Information System (INIS)
Belytschko, T.; Liu, W.K.
1985-01-01
Fluid-structure interaction problems in nuclear engineering are categorized according to the dominant physical phenomena and the appropriate computational methods. Linear fluid models that are considered include acoustic fluids, incompressible fluids undergoing small disturbances, and small amplitude sloshing. Methods available in general-purpose codes for these linear fluid problems are described. For nonlinear fluid problems, the major features of alternative computational treatments are reviewed; some special-purpose and multipurpose computer codes applicable to these problems are then described. For illustration, some examples of nuclear reactor problems that entail coupled fluid-structure analysis are described along with computational results
Interface between computational fluid dynamics (CFD) and plant analysis computer codes
International Nuclear Information System (INIS)
Coffield, R.D.; Dunckhorst, F.F.; Tomlinson, E.T.; Welch, J.W.
1993-01-01
Computational fluid dynamics (CFD) can provide valuable input to the development of advanced plant analysis computer codes. The types of interfacing discussed in this paper will directly contribute to modeling and accuracy improvements throughout the plant system and should result in significant reduction of design conservatisms that have been applied to such analyses in the past
Multitasking the code ARC3D. [for computational fluid dynamics
Barton, John T.; Hsiung, Christopher C.
1986-01-01
The CRAY multitasking system was developed in order to utilize all four processors and sharply reduce the wall clock run time. This paper describes the techniques used to modify the computational fluid dynamics code ARC3D for this run and analyzes the achieved speedup. The ARC3D code solves either the Euler or thin-layer N-S equations using an implicit approximate factorization scheme. Results indicate that multitask processing can be used to achieve wall clock speedup factors of over three times, depending on the nature of the program code being used. Multitasking appears to be particularly advantageous for large-memory problems running on multiple CPU computers.
International Nuclear Information System (INIS)
Pshenichnikov, A.F.
2012-01-01
A new algorithm for calculating magnetic fields in a concentrated magnetic fluid with inhomogeneous density is proposed. Inhomogeneity of the fluid is caused by magnetophoresis. In this case, the diffusion and magnetostatic parts of the problem are tightly linked together and are solved jointly. The dynamic diffusion equation is solved by the finite volume method and, to calculate the magnetic field inside the fluid, an iterative process is performed in parallel. The solution to the problem is sought in Cartesian coordinates, and the computational domain is decomposed into rectangular elements. This technique eliminates the need to solve the related boundary-value problem for magnetic fields, accelerates computations and eliminates the error caused by the finite sizes of the outer region. Formulas describing the contribution of the rectangular element to the field intensity in the case of a plane problem are given. Magnetic and concentration fields inside the magnetic fluid filling a rectangular cavity generated under the action of the uniform external filed are calculated. - Highlights: ▶ New algorithm for calculating magnetic field intense magnetic fluid with account of magnetophoresis and diffusion of particles. ▶ We do not need to solve boundary-value problem, but we accelerate computations and eliminate some errors. ▶ We solve nonlinear flow equation by the finite volume method and calculate magnetic and focus fields in the fluid for plane case.
Jäger, Willi
2003-01-01
This book presents the state-of-the-art in modeling and simulation on supercomputers. Leading German research groups present their results achieved on high-end systems of the High Performance Computing Center Stuttgart (HLRS) for the year 2002. Reports cover all fields of supercomputing simulation ranging from computational fluid dynamics to computer science. Special emphasis is given to industrially relevant applications. Moreover, by presenting results for both vector sytems and micro-processor based systems the book allows to compare performance levels and usability of a variety of supercomputer architectures. It therefore becomes an indispensable guidebook to assess the impact of the Japanese Earth Simulator project on supercomputing in the years to come.
Gentzsch, Wolfgang
1986-01-01
The GAMM Committee for Numerical Methods in Fluid Mechanics organizes workshops which should bring together experts of a narrow field of computational fluid dynamics (CFD) to exchange ideas and experiences in order to speed-up the development in this field. In this sense it was suggested that a workshop should treat the solution of CFD problems on vector computers. Thus we organized a workshop with the title "The efficient use of vector computers with emphasis on computational fluid dynamics". The workshop took place at the Computing Centre of the University of Karlsruhe, March 13-15,1985. The participation had been restricted to 22 people of 7 countries. 18 papers have been presented. In the announcement of the workshop we wrote: "Fluid mechanics has actively stimulated the development of superfast vector computers like the CRAY's or CYBER 205. Now these computers on their turn stimulate the development of new algorithms which result in a high degree of vectorization (sca1ar/vectorized execution-time). But w...
Improving engineers' performance with computers
International Nuclear Information System (INIS)
Purvis, E.E. III
1984-01-01
The problem addressed is how to improve the performance of engineers in the design, operation, and maintenance of nuclear power plants. The application of computer science to this problem offers a challenge in maximizing the use of developments outside the nuclear industry and setting priorities to address the most fruitful areas first. Areas of potential benefits include data base management through design, analysis, procurement, construction, operation maintenance, cost, schedule and interface control and planning, and quality engineering on specifications, inspection, and training
Issues in computational fluid dynamics code verification and validation
Energy Technology Data Exchange (ETDEWEB)
Oberkampf, W.L.; Blottner, F.G.
1997-09-01
A broad range of mathematical modeling errors of fluid flow physics and numerical approximation errors are addressed in computational fluid dynamics (CFD). It is strongly believed that if CFD is to have a major impact on the design of engineering hardware and flight systems, the level of confidence in complex simulations must substantially improve. To better understand the present limitations of CFD simulations, a wide variety of physical modeling, discretization, and solution errors are identified and discussed. Here, discretization and solution errors refer to all errors caused by conversion of the original partial differential, or integral, conservation equations representing the physical process, to algebraic equations and their solution on a computer. The impact of boundary conditions on the solution of the partial differential equations and their discrete representation will also be discussed. Throughout the article, clear distinctions are made between the analytical mathematical models of fluid dynamics and the numerical models. Lax`s Equivalence Theorem and its frailties in practical CFD solutions are pointed out. Distinctions are also made between the existence and uniqueness of solutions to the partial differential equations as opposed to the discrete equations. Two techniques are briefly discussed for the detection and quantification of certain types of discretization and grid resolution errors.
FAST - A multiprocessed environment for visualization of computational fluid dynamics
International Nuclear Information System (INIS)
Bancroft, G.V.; Merritt, F.J.; Plessel, T.C.; Kelaita, P.G.; Mccabe, R.K.
1991-01-01
The paper presents the Flow Analysis Software Toolset (FAST) to be used for fluid-mechanics analysis. The design criteria for FAST including the minimization of the data path in the computational fluid-dynamics (CFD) process, consistent user interface, extensible software architecture, modularization, and the isolation of three-dimensional tasks from the application programmer are outlined. Each separate process communicates through the FAST Hub, while other modules such as FAST Central, NAS file input, CFD calculator, surface extractor and renderer, titler, tracer, and isolev might work together to generate the scene. An interprocess communication package making it possible for FAST to operate as a modular environment where resources could be shared among different machines as well as a single host is discussed. 20 refs
Extensive use of computational fluid dynamics in the upgrading of hydraulic turbines
Energy Technology Data Exchange (ETDEWEB)
Sabourin, M.; De Henau, V. [GEC Alsthom Electromechanical Inc., Tracy, PQ (Canada); Eremeef, R. [GEC Alsthom Neyrpic, Grenoble (France)
1995-12-31
The use of computational fluid flow dynamics (CFD) and the Navier Stokes equations by GEC Alsthom for turbine rehabilitation were discussed. The process of runner rehabilitation was discussed from a fluid flow perspective, which accounts for the spiral case-distributor set and draft tube. The Kootenay turbine rehabilitation was described with regard to it spiral case and stay vane. The numerical analysis used to model upstream components was explained. The influence of draft tube effects was emphasized as an important efficiency factor. The differences between draft tubes at Sir Adam Beck 2 and La Grande 2 were discussed. Computational fluid flow modelling was claimed to have produced global performance enhancements in a reasonably short time, and at a reasonable cost. 6 refs., 6 figs., 4 tabs.
Disk brake design for cooling improvement using Computational Fluid Dynamics (CFD)
International Nuclear Information System (INIS)
Munisamy, Kannan M; Shafik, Ramel
2013-01-01
The car disk brake design is improved with two different blade designs compared to the baseline blade design. The two designs were simulated in Computational fluid dynamics (CFD) to obtain heat transfer properties such as Nusselt number and Heat transfer coefficient. The heat transfer property is compared against the baseline design. The improved shape has the highest heat transfer performance. The curved design is inferior to baseline design in heat transfer performance.
Disk brake design for cooling improvement using Computational Fluid Dynamics (CFD)
Munisamy, Kannan M.; Shafik, Ramel
2013-06-01
The car disk brake design is improved with two different blade designs compared to the baseline blade design. The two designs were simulated in Computational fluid dynamics (CFD) to obtain heat transfer properties such as Nusselt number and Heat transfer coefficient. The heat transfer property is compared against the baseline design. The improved shape has the highest heat transfer performance. The curved design is inferior to baseline design in heat transfer performance.
Computational fluid dynamics study of viscous fingering in supercritical fluid chromatography.
Subraveti, Sai Gokul; Nikrityuk, Petr; Rajendran, Arvind
2018-01-26
Axi-symmetric numerical simulations are carried out to study the dynamics of a plug introduced through a mixed-stream injection in supercritical fluid chromatographic columns. The computational fluid dynamics model developed in this work takes into account both the hydrodynamics and adsorption equilibria to describe the phenomena of viscous fingering and plug effect that contribute to peak distortions in mixed-stream injections. The model was implemented into commercial computational fluid dynamics software using user-defined functions. The simulations describe the propagation of both the solute and modifier highlighting the interplay between the hydrodynamics and plug effect. The simulated peaks showed good agreement with experimental data published in the literature involving different injection volumes (5 μL, 50 μL, 1 mL and 2 mL) of flurbiprofen on Chiralpak AD-H column using a mobile phase of CO 2 and methanol. The study demonstrates that while viscous fingering is the main source of peak distortions for large-volume injections (1 mL and 2 mL) it has negligible impact on small-volume injections (5 μL and 50 μL). Band broadening in small-volume injections arise mainly due to the plug effect. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.
Babu, C. Rajesh; Kumar, P.; Rajamohan, G.
2017-07-01
Computation of fluid flow and heat transfer in an economizer is simulated by a porous medium approach, with plain tubes having a horizontal in-line arrangement and cross flow arrangement in a coal-fired thermal power plant. The economizer is a thermal mechanical device that captures waste heat from the thermal exhaust flue gasses through heat transfer surfaces to preheat boiler feed water. In order to evaluate the fluid flow and heat transfer on tubes, a numerical analysis on heat transfer performance is carried out on an 110 t/h MCR (Maximum continuous rating) boiler unit. In this study, thermal performance is investigated using the computational fluid dynamics (CFD) simulation using ANSYS FLUENT. The fouling factor ε and the overall heat transfer coefficient ψ are employed to evaluate the fluid flow and heat transfer. The model demands significant computational details for geometric modeling, grid generation, and numerical calculations to evaluate the thermal performance of an economizer. The simulation results show that the overall heat transfer coefficient 37.76 W/(m2K) and economizer coil side pressure drop of 0.2 (kg/cm2) are found to be conformity within the tolerable limits when compared with existing industrial economizer data.
Computational Fluid Dynamics (CFD) Technology Programme 1995- 1999
Energy Technology Data Exchange (ETDEWEB)
Haekkinen, R.J.; Hirsch, C.; Krause, E.; Kytoemaa, H.K. [eds.
1997-12-31
The report is a mid-term evaluation of the Computational Fluid Dynamics (CFD) Technology Programme started by Technology Development Centre Finland (TEKES) in 1995 as a five-year initiative to be concluded in 1999. The main goal of the programme is to increase the know-how and application of CFD in Finnish industry, to coordinate and thus provide a better basis for co-operation between national CFD activities and encouraging research laboratories and industry to establish co-operation with the international CFD community. The projects of the programme focus on the following areas: (1) studies of modeling the physics and dynamics of the behaviour of fluid material, (2) expressing the physical models in a numerical mode and developing a computer codes, (3) evaluating and testing current physical models and developing new ones, (4) developing new numerical algorithms, solvers, and pre- and post-processing software, and (5) applying the new computational tools to problems relevant to their ultimate industrial use. The report consists of two sections. The first considers issues concerning the whole programme and the second reviews each project
A computer model for dispersed fluid-solid turbulent flows
International Nuclear Information System (INIS)
Liu, C.H.; Tulig, T.J.
1985-01-01
A computer model is being developed to simulate two-phase turbulent flow phenomena in fluids containing finely dispersed solids. The model is based on a dual-continuum picture of the individual phases and an extension of a two-equation turbulence closure theory. The resulting set of nonlinear partial differential equations are solved using a finite difference procedure with special treatment to promote convergence. The model has been checked against a number of idealized flow problems with known solutions. The authors are currently comparing model predictions with measurements to determine a proper set of turbulence parameters needed for simulating two-phase turbulent flows
Computational fluid dynamics in fire engineering theory, modelling and practice
Yuen, Kwok Kit
2009-01-01
Fire and combustion presents a significant engineering challenge to mechanical, civil and dedicated fire engineers, as well as specialists in the process and chemical, safety, buildings and structural fields. We are reminded of the tragic outcomes of 'untenable' fire disasters such as at King's Cross underground station or Switzerland's St Gotthard tunnel. In these and many other cases, computational fluid dynamics (CFD) is at the forefront of active research into unravelling the probable causes of fires and helping to design structures and systems to ensure that they are less likely in the f
Approaching multiphase flows from the perspective of computational fluid dynamics
International Nuclear Information System (INIS)
Banas, A.O.
1992-01-01
Thermalhydraulic simulation methodologies based on subchannel and porous-medium concepts are briefly reviewed and contrasted with the general approach of Computational Fluid Dynamics (CFD). An outline of the advanced CFD methods for single-phase turbulent flows is followed by a short discussion of the unified formulation of averaged equations for turbulent and multiphase flows. Some of the recent applications of CFD at Chalk River Laboratories are discussed, and the complementary role of CFD with regard to the established thermalhydraulic methods of analysis is indicated. (author). 8 refs
Techniques for animation of CFD results. [computational fluid dynamics
Horowitz, Jay; Hanson, Jeffery C.
1992-01-01
Video animation is becoming increasingly vital to the computational fluid dynamics researcher, not just for presentation, but for recording and comparing dynamic visualizations that are beyond the current capabilities of even the most powerful graphic workstation. To meet these needs, Lewis Research Center has recently established a facility to provide users with easy access to advanced video animation capabilities. However, producing animation that is both visually effective and scientifically accurate involves various technological and aesthetic considerations that must be understood both by the researcher and those supporting the visualization process. These considerations include: scan conversion, color conversion, and spatial ambiguities.
Energy Technology Data Exchange (ETDEWEB)
Xia, Yidong [Idaho National Lab. (INL), Idaho Falls, ID (United States); Andrs, David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Martineau, Richard Charles [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2016-08-01
This document presents the theoretical background for a hybrid finite-element / finite-volume fluid flow solver, namely BIGHORN, based on the Multiphysics Object Oriented Simulation Environment (MOOSE) computational framework developed at the Idaho National Laboratory (INL). An overview of the numerical methods used in BIGHORN are discussed and followed by a presentation of the formulation details. The document begins with the governing equations for the compressible fluid flow, with an outline of the requisite constitutive relations. A second-order finite volume method used for solving the compressible fluid flow problems is presented next. A Pressure-Corrected Implicit Continuous-fluid Eulerian (PCICE) formulation for time integration is also presented. The multi-fluid formulation is being developed. Although multi-fluid is not fully-developed, BIGHORN has been designed to handle multi-fluid problems. Due to the flexibility in the underlying MOOSE framework, BIGHORN is quite extensible, and can accommodate both multi-species and multi-phase formulations. This document also presents a suite of verification & validation benchmark test problems for BIGHORN. The intent for this suite of problems is to provide baseline comparison data that demonstrates the performance of the BIGHORN solution methods on problems that vary in complexity from laminar to turbulent flows. Wherever possible, some form of solution verification has been attempted to identify sensitivities in the solution methods, and suggest best practices when using BIGHORN.
Computed radiography systems performance evaluation
International Nuclear Information System (INIS)
Xavier, Clarice C.; Nersissian, Denise Y.; Furquim, Tania A.C.
2009-01-01
The performance of a computed radiography system was evaluated, according to the AAPM Report No. 93. Evaluation tests proposed by the publication were performed, and the following nonconformities were found: imaging p/ate (lP) dark noise, which compromises the clinical image acquired using the IP; exposure indicator uncalibrated, which can cause underexposure to the IP; nonlinearity of the system response, which causes overexposure; resolution limit under the declared by the manufacturer and erasure thoroughness uncalibrated, impairing structures visualization; Moire pattern visualized at the grid response, and IP Throughput over the specified by the manufacturer. These non-conformities indicate that digital imaging systems' lack of calibration can cause an increase in dose in order that image prob/ems can be so/ved. (author)
Thorp, Scott A.
1992-01-01
This presentation will discuss the development of a NASA Geometry Exchange Specification for transferring aerodynamic surface geometry between LeRC systems and grid generation software used for computational fluid dynamics research. The proposed specification is based on a subset of the Initial Graphics Exchange Specification (IGES). The presentation will include discussion of how the NASA-IGES standard will accommodate improved computer aided design inspection methods and reverse engineering techniques currently being developed. The presentation is in viewgraph format.
Generalized added masses computation for fluid structure interaction
International Nuclear Information System (INIS)
Lazzeri, L.; Cecconi, S.; Scala, M.
1983-01-01
The aim of this paper a description of a method to simulate the dynamic effect of a fluid between two structures by means of an added mass and an added stiffness. The method is based on a potential theory which assumes the fluid is inviscid and incompressible (the case of compressibility is discussed); a solution of the corresponding field equation is given as a superposition of elementary conditions (i.e. applicable to elementary boundary conditions). Consequently the pressure and displacements of the fluid on the boundary are given as a function of the series coefficients; the ''work lost'' (i.e. the work done by the pressures on the difference between actual and estimated displacements) is minimized, in this way the expansion coefficients are related to the displacements on the boundaries. Virtual work procedures are then used to compute added masses. The particular case of a free surface (with gravity effects) is discussed, it is shown how the effect can be modelled by means of an added stiffness term. Some examples relative to vibrations in reservoirs are given and discussed. (orig.)
Computational transport phenomena of fluid-particle systems
Arastoopour, Hamid; Abbasi, Emad
2017-01-01
This book concerns the most up-to-date advances in computational transport phenomena (CTP), an emerging tool for the design of gas-solid processes such as fluidized bed systems. The authors examine recent work in kinetic theory and CTP and illustrate gas-solid processes’ many applications in the energy, chemical, pharmaceutical, and food industries. They also discuss the kinetic theory approach in developing constitutive equations for gas-solid flow systems and how it has advanced over the last decade as well as the possibility of obtaining innovative designs for multiphase reactors, such as those needed to capture CO2 from flue gases. Suitable as a concise reference and a textbook supplement for graduate courses, Computational Transport Phenomena of Gas-Solid Systems is ideal for practitioners in industries involved with the design and operation of processes based on fluid/particle mixtures, such as the energy, chemicals, pharmaceuticals, and food processing. Explains how to couple the population balance e...
Zimoń, Małgorzata; Sawko, Robert; Emerson, David; Thompson, Christopher
2017-11-01
Uncertainty quantification (UQ) is increasingly becoming an indispensable tool for assessing the reliability of computational modelling. Efficient handling of stochastic inputs, such as boundary conditions, physical properties or geometry, increases the utility of model results significantly. We discuss the application of non-intrusive generalised polynomial chaos techniques in the context of fluid engineering simulations. Deterministic and Monte Carlo integration rules are applied to a set of problems, including ordinary differential equations and the computation of aerodynamic parameters subject to random perturbations. In particular, we analyse acoustic wave propagation in a heterogeneous medium to study the effects of mesh resolution, transients, number and variability of stochastic inputs. We consider variants of multi-level Monte Carlo and perform a novel comparison of the methods with respect to numerical and parametric errors, as well as computational cost. The results provide a comprehensive view of the necessary steps in UQ analysis and demonstrate some key features of stochastic fluid flow systems.
Extensive use of computational fluid dynamics in the upgrading of hydraulic turbines
Energy Technology Data Exchange (ETDEWEB)
Sabourin, M.; Eremeef, R.; De Henau, V.
1995-12-31
Computational fluid dynamics codes, based on turbulent Navier-Stokes equations, allow evaluation of the hydraulic losses of each turbine component with precision. Using those codes with the new generation of computers enables a wide variety of component geometries to be modelled and compared to the original designs under flow conditions obtained from testing, at a reasonable cost and in a relatively short time. This paper reviews the actual method used in the design of a solution to a turbine rehabilitation project involving runner replacement, redesign of upstream components (stay vanes and wicket gates), and downstream components (draft tubes and runner outlets). The paper shows how computational fluid dynamics can help hydraulic engineers to obtain valuable information not only on performance enhancement but also on the phenomena that produce the enhancement, and to reduce the variety of modifications to be tested.
Computational Fluid Dynamics Analysis of High Injection Pressure Blended Biodiesel
Khalid, Amir; Jaat, Norrizam; Faisal Hushim, Mohd; Manshoor, Bukhari; Zaman, Izzuddin; Sapit, Azwan; Razali, Azahari
2017-08-01
Biodiesel have great potential for substitution with petrol fuel for the purpose of achieving clean energy production and emission reduction. Among the methods that can control the combustion properties, controlling of the fuel injection conditions is one of the successful methods. The purpose of this study is to investigate the effect of high injection pressure of biodiesel blends on spray characteristics using Computational Fluid Dynamics (CFD). Injection pressure was observed at 220 MPa, 250 MPa and 280 MPa. The ambient temperature was kept held at 1050 K and ambient pressure 8 MPa in order to simulate the effect of boost pressure or turbo charger during combustion process. Computational Fluid Dynamics were used to investigate the spray characteristics of biodiesel blends such as spray penetration length, spray angle and mixture formation of fuel-air mixing. The results shows that increases of injection pressure, wider spray angle is produced by biodiesel blends and diesel fuel. The injection pressure strongly affects the mixture formation, characteristics of fuel spray, longer spray penetration length thus promotes the fuel and air mixing.
Computer simulations of equilibrium magnetization and microstructure in magnetic fluids
Rosa, A. P.; Abade, G. C.; Cunha, F. R.
2017-09-01
In this work, Monte Carlo and Brownian Dynamics simulations are developed to compute the equilibrium magnetization of a magnetic fluid under action of a homogeneous applied magnetic field. The particles are free of inertia and modeled as hard spheres with the same diameters. Two different periodic boundary conditions are implemented: the minimum image method and Ewald summation technique by replicating a finite number of particles throughout the suspension volume. A comparison of the equilibrium magnetization resulting from the minimum image approach and Ewald sums is performed by using Monte Carlo simulations. The Monte Carlo simulations with minimum image and lattice sums are used to investigate suspension microstructure by computing the important radial pair-distribution function go(r), which measures the probability density of finding a second particle at a distance r from a reference particle. This function provides relevant information on structure formation and its anisotropy through the suspension. The numerical results of go(r) are compared with theoretical predictions based on quite a different approach in the absence of the field and dipole-dipole interactions. A very good quantitative agreement is found for a particle volume fraction of 0.15, providing a validation of the present simulations. In general, the investigated suspensions are dominated by structures like dimmer and trimmer chains with trimmers having probability to form an order of magnitude lower than dimmers. Using Monte Carlo with lattice sums, the density distribution function g2(r) is also examined. Whenever this function is different from zero, it indicates structure-anisotropy in the suspension. The dependence of the equilibrium magnetization on the applied field, the magnetic particle volume fraction, and the magnitude of the dipole-dipole magnetic interactions for both boundary conditions are explored in this work. Results show that at dilute regimes and with moderate dipole
Performances of Magnetic Fluid Seal and Application to Turbopumps
北洞, 貴也; 黒川, 淳一; 宮副, 雄貴; 林, 正悦
1994-01-01
A magnetic fluid shaft seal can achieve zero-leakage and operate stably against shaft vibration, but the sealing pressure is very low. In order to improve the pressure performance of a magnetic fluid seal and apply it to a turbopump, the seal pressure characteristics are studied theoretically and experimentally. The Poisson equation for magnetic vector potential is solved by FEM, and the seal performances are determined by use of the Bernoulli equation. The validity of the theory is confirmed...
Development of real-time visualization system for Computational Fluid Dynamics on parallel computers
International Nuclear Information System (INIS)
Muramatsu, Kazuhiro; Otani, Takayuki; Matsumoto, Hideki; Takei, Toshifumi; Doi, Shun
1998-03-01
A real-time visualization system for computational fluid dynamics in a network connecting between a parallel computing server and the client terminal was developed. Using the system, a user can visualize the results of a CFD (Computational Fluid Dynamics) simulation on the parallel computer as a client terminal during the actual computation on a server. Using GUI (Graphical User Interface) on the client terminal, to user is also able to change parameters of the analysis and visualization during the real-time of the calculation. The system carries out both of CFD simulation and generation of a pixel image data on the parallel computer, and compresses the data. Therefore, the amount of data from the parallel computer to the client is so small in comparison with no compression that the user can enjoy the swift image appearance comfortably. Parallelization of image data generation is based on Owner Computation Rule. GUI on the client is built on Java applet. A real-time visualization is thus possible on the client PC only if Web browser is implemented on it. (author)
OpenDx programs for visualization of computational fluid dynamics (CFD) simulations
International Nuclear Information System (INIS)
Silva, Marcelo Mariano da
2008-01-01
The search for high performance and low cost hardware and software solutions always guides the developments performed at the IEN parallel computing laboratory. In this context, this dissertation about the building of programs for visualization of computational fluid dynamics (CFD) simulations using the open source software OpenDx was written. The programs developed are useful to produce videos and images in two or three dimensions. They are interactive, easily to use and were designed to serve fluid dynamics researchers. A detailed description about how this programs were developed and the complete instructions of how to use them was done. The use of OpenDx as development tool is also introduced. There are examples that help the reader to understand how programs can be useful for many applications. (author)
An Integrated Solution for Performing Thermo-fluid Conjugate Analysis
Kornberg, Oren
2009-01-01
A method has been developed which integrates a fluid flow analyzer and a thermal analyzer to produce both steady state and transient results of 1-D, 2-D, and 3-D analysis models. The Generalized Fluid System Simulation Program (GFSSP) is a one dimensional, general purpose fluid analysis code which computes pressures and flow distributions in complex fluid networks. The MSC Systems Improved Numerical Differencing Analyzer (MSC.SINDA) is a one dimensional general purpose thermal analyzer that solves network representations of thermal systems. Both GFSSP and MSC.SINDA have graphical user interfaces which are used to build the respective model and prepare it for analysis. The SINDA/GFSSP Conjugate Integrator (SGCI) is a formbase graphical integration program used to set input parameters for the conjugate analyses and run the models. The contents of this paper describes SGCI and its thermo-fluids conjugate analysis techniques and capabilities by presenting results from some example models including the cryogenic chill down of a copper pipe, a bar between two walls in a fluid stream, and a solid plate creating a phase change in a flowing fluid.
2009-01-01
At the 19th Annual Conference on Parallel Computational Fluid Dynamics held in Antalya, Turkey, in May 2007, the most recent developments and implementations of large-scale and grid computing were presented. This book, comprised of the invited and selected papers of this conference, details those advances, which are of particular interest to CFD and CFD-related communities. It also offers the results related to applications of various scientific and engineering problems involving flows and flow-related topics. Intended for CFD researchers and graduate students, this book is a state-of-the-art presentation of the relevant methodology and implementation techniques of large-scale computing.
APPLICATION OF COMPUTATIONAL FLUID DYNAMICS MODELLING TO A HORIZONTAL SEDIMENTATION TANK IN IRAQ
Ali Hadi GHAWI
2017-01-01
Computational Fluid Dynamics modeling has been applied to examine the hydrodynamic behavior of water treatment sedimentation tanks at Baghdad Water Works, operated by Alkurech Water in Baghdad in Iraq. The existing tanks perform poorly at current flows and flow is unevenly split among online tanks, Therefore, CFD was used to investigate velocity profiles at current and projected loadings for the existing basins. Results from the CFD analysis were used to develop retrofit strategies to improve...
Blocken, B.J.E.; Gualtieri, C.
2012-01-01
Computational Fluid Dynamics (CFD) is increasingly used to study a wide variety of complex Environmental Fluid Mechanics (EFM) processes, such as water flow and turbulent mixing of contaminants in rivers and estuaries and wind flow and air pollution dispersion in urban areas. However, the accuracy
High Performance Spaceflight Computing (HPSC)
National Aeronautics and Space Administration — Space-based computing has not kept up with the needs of current and future NASA missions. We are developing a next-generation flight computing system that addresses...
Cepstrum analysis and applications to computational fluid dynamic solutions
Meadows, Kristine R.
1990-04-01
A novel approach to the problem of spurious reflections introduced by artificial boundary conditions in computational fluid dynamic (CFD) solutions is proposed. Instead of attempting to derive non-reflecting boundary conditions, the approach is to accept the fact that spurious reflections occur, but to remove these reflections with cepstrum analysis, a signal processing technique which has been successfully used to remove echoes from experimental data. First, the theory of the cepstrum method is presented. This includes presentation of two types of cepstra: The Power Cepstrum and the Complex Cepstrum. The definitions of the cepstrum methods are applied theoretically and numerically to the analytical solution of sinusoidal plane wave propagation in a duct. One-D and 3-D time dependent solutions to the Euler equations are computed, and hard-wall conditions are prescribed at the numerical boundaries. The cepstrum method is applied, and the reflections from the boundaries are removed from the solutions. One-D and 3-D solutions are computed with so called nonreflecting boundary conditions, and these solutions are compared to those obtained by prescribing hard wall conditions and processing with the cepstrum.
Computational fluid dynamic modeling of fluidized-bed polymerization reactors
Energy Technology Data Exchange (ETDEWEB)
Rokkam, Ram [Iowa State Univ., Ames, IA (United States)
2012-01-01
Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified using simple test cases, validated with experiments and applied to a pilot-scale polymerization fluidized-bed reactor. The CFD model reproduced qualitative trends in particle segregation and entrainment due to electrostatic charges observed in experiments. For the scale up of fluidized bed reactor, filtered models are developed and implemented on pilot scale reactor.
Computational Fluid Dynamic Analysis of a Vibrating Turbine Blade
Directory of Open Access Journals (Sweden)
Osama N. Alshroof
2012-01-01
Full Text Available This study presents the numerical fluid-structure interaction (FSI modelling of a vibrating turbine blade using the commercial software ANSYS-12.1. The study has two major aims: (i discussion of the current state of the art of modelling FSI in gas turbine engines and (ii development of a “tuned” one-way FSI model of a vibrating turbine blade to investigate the correlation between the pressure at the turbine casing surface and the vibrating blade motion. Firstly, the feasibility of the complete FSI coupled two-way, three-dimensional modelling of a turbine blade undergoing vibration using current commercial software is discussed. Various modelling simplifications, which reduce the full coupling between the fluid and structural domains, are then presented. The one-way FSI model of the vibrating turbine blade is introduced, which has the computational efficiency of a moving boundary CFD model. This one-way FSI model includes the corrected motion of the vibrating turbine blade under given engine flow conditions. This one-way FSI model is used to interrogate the pressure around a vibrating gas turbine blade. The results obtained show that the pressure distribution at the casing surface does not differ significantly, in its general form, from the pressure at the vibrating rotor blade tip.
Review of computational fluid dynamics applications in biotechnology processes.
Sharma, C; Malhotra, D; Rathore, A S
2011-01-01
Computational fluid dynamics (CFD) is well established as a tool of choice for solving problems that involve one or more of the following phenomena: flow of fluids, heat transfer,mass transfer, and chemical reaction. Unit operations that are commonly utilized in biotechnology processes are often complex and as such would greatly benefit from application of CFD. The thirst for deeper process and product understanding that has arisen out of initiatives such as quality by design provides further impetus toward usefulness of CFD for problems that may otherwise require extensive experimentation. Not surprisingly, there has been increasing interest in applying CFD toward a variety of applications in biotechnology processing in the last decade. In this article, we will review applications in the major unit operations involved with processing of biotechnology products. These include fermentation,centrifugation, chromatography, ultrafiltration, microfiltration, and freeze drying. We feel that the future applications of CFD in biotechnology processing will focus on establishing CFD as a tool of choice for providing process understanding that can be then used to guide more efficient and effective experimentation. This article puts special emphasis on the work done in the last 10 years. © 2011 American Institute of Chemical Engineers
Modeling centrifugal cell washers using computational fluid dynamics.
Kellet, Beth E; Han, Binbing; Dandy, David S; Wickramasinghe, S Ranil
2004-11-01
Reinfusion of shed blood during surgery could avoid the need for blood transfusions. Prior to reinfusion of the red blood cells, the shed blood must be washed in order to remove leukocytes, platelets, and other contaminants. Further, the hematocrit of the washed blood must be increased. The feasibility of using computational fluid dynamics (CFD) to guide the design of better centrifuges for processing shed blood is explored here. The velocity field within a centrifuge bowl and the rate of protein removal from the shed blood has been studied. The results obtained indicate that CFD could help screen preliminary centrifuge bowl designs, thus reducing the number of initial experimental tests required when developing new centrifuge bowls. Although the focus of this work is on washing shed blood, the methods developed here are applicable to the design of centrifuge bowls for other blood-processing applications.
Personal Computer (PC) based image processing applied to fluid mechanics
Cho, Y.-C.; Mclachlan, B. G.
1987-01-01
A PC based image processing system was employed to determine the instantaneous velocity field of a two-dimensional unsteady flow. The flow was visualized using a suspension of seeding particles in water, and a laser sheet for illumination. With a finite time exposure, the particle motion was captured on a photograph as a pattern of streaks. The streak pattern was digitized and processed using various imaging operations, including contrast manipulation, noise cleaning, filtering, statistical differencing, and thresholding. Information concerning the velocity was extracted from the enhanced image by measuring the length and orientation of the individual streaks. The fluid velocities deduced from the randomly distributed particle streaks were interpolated to obtain velocities at uniform grid points. For the interpolation a simple convolution technique with an adaptive Gaussian window was used. The results are compared with a numerical prediction by a Navier-Stokes computation.
Improving coal flotation recovery using computational fluid dynamics
Energy Technology Data Exchange (ETDEWEB)
Peter Koh [CSIRO Minerals (Australia)
2009-06-15
This work involves using the latest advances in computational fluid dynamics (CFD) to increase understanding of the hydrodynamics in coal flotation and to identify any opportunities to improve design and operation of both the Microcel column and Jameson cell. The CSIRO CFD model incorporates micro-processes from cell hydrodynamics that affect particle-bubble attachments and detachments. CFD simulation results include the liquid velocities, turbulent dissipation rates, gas hold-up, particle-bubble attachment rates and detachment rates. This work has demonstrated that CFD modelling is a cost effective means of developing an understanding of particle-bubble attachments and detachments, and can be used to identify and test potential cell or process modifications.
Simulation of Tailrace Hydrodynamics Using Computational Fluid Dynamics Models
Energy Technology Data Exchange (ETDEWEB)
Cook, Christopher B.; Richmond, Marshall C.
2001-05-01
This report investigates the feasibility of using computational fluid dynamics (CFD) tools to investigate hydrodynamic flow fields surrounding the tailrace zone below large hydraulic structures. Previous and ongoing studies using CFD tools to simulate gradually varied flow with multiple constituents and forebay/intake hydrodynamics have shown that CFD tools can provide valuable information for hydraulic and biological evaluation of fish passage near hydraulic structures. These studies however are incapable of simulating the rapidly varying flow fields that involving breakup of the free-surface, such as those through and below high flow outfalls and spillways. Although the use of CFD tools for these types of flow are still an active area of research, initial applications discussed in this report show that these tools are capable of simulating the primary features of these highly transient flow fields.
Qweak Data Analysis for Target Modeling Using Computational Fluid Dynamics
Moore, Michael; Covrig, Silviu
2015-04-01
The 2.5 kW liquid hydrogen (LH2) target used in the Qweak parity violation experiment is the highest power LH2 target in the world and the first to be designed with Computational Fluid Dynamics (CFD) at Jefferson Lab. The Qweak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from unpolarized liquid hydrogen at small momentum transfer (Q2 = 0 . 025 GeV2). This target met the design goals of bench-marked with the Qweak target data. This work is an essential ingredient in future designs of very high power low noise targets like MOLLER (5 kW, target noise asymmetry contribution < 25 ppm) and MESA (4.5 kW).
Computational Fluid Dynamics Analysis of an Evaporative Cooling System
Directory of Open Access Journals (Sweden)
Kapilan N.
2016-11-01
Full Text Available The use of chlorofluorocarbon based refrigerants in the air-conditioning system increases the global warming and causes the climate change. The climate change is expected to present a number of challenges for the built environment and an evaporative cooling system is one of the simplest and environmentally friendly cooling system. The evaporative cooling system is most widely used in summer and in rural and urban areas of India for human comfort. In evaporative cooling system, the addition of water into air reduces the temperature of the air as the energy needed to evaporate the water is taken from the air. Computational fluid dynamics is a numerical analysis and was used to analyse the evaporative cooling system. The CFD results are matches with the experimental results.
Simulating Smoke Filling in Big Halls by Computational Fluid Dynamics
Directory of Open Access Journals (Sweden)
W. K. Chow
2011-01-01
Full Text Available Many tall halls of big space volume were built and, to be built in many construction projects in the Far East, particularly Mainland China, Hong Kong, and Taiwan. Smoke is identified to be the key hazard to handle. Consequently, smoke exhaust systems are specified in the fire code in those areas. An update on applying Computational Fluid Dynamics (CFD in smoke exhaust design will be presented in this paper. Key points to note in CFD simulations on smoke filling due to a fire in a big hall will be discussed. Mathematical aspects concerning of discretization of partial differential equations and algorithms for solving the velocity-pressure linked equations are briefly outlined. Results predicted by CFD with different free boundary conditions are compared with those on room fire tests. Standards on grid size, relaxation factors, convergence criteria, and false diffusion should be set up for numerical experiments with CFD.
Computational Fluid Dynamics of Choanoflagellate Filter-Feeding
Asadzadeh, Seyed Saeed; Walther, Jens; Nielsen, Lasse Tore; Kiorboe, Thomas; Dolger, Julia; Andersen, Anders
2017-11-01
Choanoflagellates are unicellular aquatic organisms with a single flagellum that drives a feeding current through a funnel-shaped collar filter on which bacteria-sized prey are caught. Using computational fluid dynamics (CFD) we model the beating flagellum and the complex filter flow of the choanoflagellate Diaphanoeca grandis. Our CFD simulations based on the current understanding of the morphology underestimate the experimentally observed clearance rate by more than an order of magnitude: The beating flagellum is simply unable to draw enough water through the fine filter. Our observations motivate us to suggest a radically different filtration mechanism that requires a flagellar vane (sheet), and addition of a wide vane in our CFD model allows us to correctly predict the observed clearance rate.
Study of blast wave overpressures using the computational fluid dynamics
Directory of Open Access Journals (Sweden)
M. L. COSTA NETO
Full Text Available ABSTRACT The threats of bomb attacks by criminal organizations and accidental events involving chemical explosives are a danger to the people and buildings. Due the severity of these issues and the need of data required for a safety design, more research is required about explosions and shock waves. This paper presents an assessment of blast wave overpressures using a computational fluid dynamics software. Analyses of phenomena as reflection of shock waves and channeling effects were done and a comparison between numerical results and analytical predictions has been executed, based on the simulation on several models. The results suggest that the common analytical predictions aren’t accurate enough for an overpressure analysis in small stand-off distances and that poorly designed buildings may increase the shock wave overpressures due multiple blast wave reflections, increasing the destructive potential of the explosions.
Mapping flow distortion on oceanographic platforms using computational fluid dynamics
Directory of Open Access Journals (Sweden)
N. O'Sullivan
2013-10-01
Full Text Available Wind speed measurements over the ocean on ships or buoys are affected by flow distortion from the platform and by the anemometer itself. This can lead to errors in direct measurements and the derived parametrisations. Here we computational fluid dynamics (CFD to simulate the errors in wind speed measurements caused by flow distortion on the RV Celtic Explorer. Numerical measurements were obtained from the finite-volume CFD code OpenFOAM, which was used to simulate the velocity fields. This was done over a range of orientations in the test domain from −60 to +60° in increments of 10°. The simulation was also set up for a range of velocities, ranging from 5 to 25 m s−1 in increments of 0.5 m s−1. The numerical analysis showed close agreement to experimental measurements.
Helicopter fuselage drag - combined computational fluid dynamics and experimental studies
Batrakov, A.; Kusyumov, A.; Mikhailov, S.; Pakhov, V.; Sungatullin, A.; Valeev, M.; Zherekhov, V.; Barakos, G.
2015-06-01
In this paper, wind tunnel experiments are combined with Computational Fluid Dynamics (CFD) aiming to analyze the aerodynamics of realistic fuselage configurations. A development model of the ANSAT aircraft and an early model of the AKTAI light helicopter were employed. Both models were tested at the subsonic wind tunnel of KNRTU-KAI for a range of Reynolds numbers and pitch and yaw angles. The force balance measurements were complemented by particle image velocimetry (PIV) investigations for the cases where the experimental force measurements showed substantial unsteadiness. The CFD results were found to be in fair agreement with the test data and revealed some flow separation at the rear of the fuselages. Once confidence on the CFD method was established, further modifications were introduced to the ANSAT-like fuselage model to demonstrate drag reduction via small shape changes.
High performance computing in Windows Azure cloud
Ambruš, Dejan
2013-01-01
High performance, security, availability, scalability, flexibility and lower costs of maintenance have essentially contributed to the growing popularity of cloud computing in all spheres of life, especially in business. In fact cloud computing offers even more than this. With usage of virtual computing clusters a runtime environment for high performance computing can be efficiently implemented also in a cloud. There are many advantages but also some disadvantages of cloud computing, some ...
Numerical computation of fluid flow in different nonferrous metallurgical reactors
International Nuclear Information System (INIS)
Lackner, A.
1996-10-01
Heat, mass and fluid flow phenomena in metallurgical reactor systems such as smelting cyclones or electrolytic cells are complex and intricately linked through the governing equations of fluid flow, chemical reaction kinetics and chemical thermodynamics. The challenges for the representation of flow phenomena in such reactors as well as the transfers of these concepts to non-specialist modelers (e.g. plant operators and management personnel) can be met through scientific flow visualization techniques. In the first example the fluid flow of the gas phase and of concentrate particles in a smelting cyclone for copper production are calculated three dimensionally. The effect of design parameters (length and diameter of reactor, concentrate feeding tangentially or from the top, ..) and operating conditions are investigated. Single particle traces show, how to increase particle retention time before the particles reach the liquid film flowing down the cyclone wall. Cyclone separators are widely used in the metallurgical and chemical industry for collection of large quantities of dust. Most of the empirical models, which today are applied for the design, are lacking in being valid in the high temperature region. Therefore the numerical prediction of the collection efficiency of dust particles is done. The particle behavior close to the wall is considered by applying a particle restitution model, which calculates individual particle restitution coefficients as functions of impact velocity and impact angle. The effect of design parameters and operating are studied. Moreover, the fluid flow inside a copper refining electrolysis cell is modeled. The simulation is based on density variations in the boundary layer at the electrode surface. Density and thickness of the boundary layer are compared to measurements in a parametric study. The actual inhibitor concentration in the cell is calculated, too. Moreover, a two-phase flow approach is developed to simulate the behavior of
Computational fluid dynamics applied to flows in an internal combustion engine
Griffin, M. D.; Diwakar, R.; Anderson, J. D., Jr.; Jones, E.
1978-01-01
The reported investigation is a continuation of studies conducted by Diwakar et al. (1976) and Griffin et al. (1976), who reported the first computational fluid dynamic results for the two-dimensional flowfield for all four strokes of a reciprocating internal combustion (IC) engine cycle. An analysis of rectangular and cylindrical three-dimensional engine models is performed. The working fluid is assumed to be inviscid air of constant specific heats. Calculations are carried out of a four-stroke IC engine flowfield wherein detailed finite-rate chemical combustion of a gasoline-air mixture is included. The calculations remain basically inviscid, except that in some instances thermal conduction is included to allow a more realistic model of the localized sparking of the mixture. All the results of the investigation are obtained by means of an explicity time-dependent finite-difference technique, using a high-speed digital computer.
Predicting the Noise of High Power Fluid Targets Using Computational Fluid Dynamics
Moore, Michael; Covrig Dusa, Silviu
The 2.5 kW liquid hydrogen (LH2) target used in the Qweak parity violation experiment is the highest power LH2 target in the world and the first to be designed with Computational Fluid Dynamics (CFD) at Jefferson Lab. The Qweak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from unpolarized liquid hydrogen at small momentum transfer (Q2 = 0 . 025 GeV2). This target satisfied the design goals of bench-marked with the Qweak target data. This work is an essential component in future designs of very high power low noise targets like MOLLER (5 kW, target noise asymmetry contribution < 25 ppm) and MESA (4.5 kW).
Lee, A. Y.
1967-01-01
Computer program calculates the steady state fluid distribution, temperature rise, and pressure drop of a coolant, the material temperature distribution of a heat generating solid, and the heat flux distributions at the fluid-solid interfaces. It performs the necessary iterations automatically within the computer, in one machine run.
International Nuclear Information System (INIS)
Li, X.L.
1993-01-01
Computation of three-dimensional (3-D) Rayleigh--Taylor instability in compressible fluids is performed on a MIMD computer. A second-order TVD scheme is applied with a fully parallelized algorithm to the 3-D Euler equations. The computational program is implemented for a 3-D study of bubble evolution in the Rayleigh--Taylor instability with varying bubble aspect ratio and for large-scale simulation of a 3-D random fluid interface. The numerical solution is compared with the experimental results by Taylor
Computer Simulation Performed for Columbia Project Cooling System
Ahmad, Jasim
2005-01-01
This demo shows a high-fidelity simulation of the air flow in the main computer room housing the Columbia (10,024 intel titanium processors) system. The simulation asseses the performance of the cooling system and identified deficiencies, and recommended modifications to eliminate them. It used two in house software packages on NAS supercomputers: Chimera Grid tools to generate a geometric model of the computer room, OVERFLOW-2 code for fluid and thermal simulation. This state-of-the-art technology can be easily extended to provide a general capability for air flow analyses on any modern computer room. Columbia_CFD_black.tiff
An Automated High Aspect Ratio Mesher for Computational Fluid Dynamics, Phase II
National Aeronautics and Space Administration — Computational fluid dynamics (CFD) simulations are routinely used while designing, analyzing, and optimizing air- and spacecraft. An important component of CFD...
National Research Council Canada - National Science Library
Faragher, John
2004-01-01
... conservatism to allow for them. This report examines the feasibility of using a probabilistic approach for modelling the component temperatures in an engine using CFD (Computational Fluid Dynamics).
Analysis of sponge zones for computational fluid mechanics
International Nuclear Information System (INIS)
Bodony, Daniel J.
2006-01-01
The use of sponge regions, or sponge zones, which add the forcing term -σ(q - q ref ) to the right-hand-side of the governing equations in computational fluid mechanics as an ad hoc boundary treatment is widespread. They are used to absorb and minimize reflections from computational boundaries and as forcing sponges to introduce prescribed disturbances into a calculation. A less common usage is as a means of extending a calculation from a smaller domain into a larger one, such as in computing the far-field sound generated in a localized region. By analogy to the penalty method of finite elements, the method is placed on a solid foundation, complete with estimates of convergence. The analysis generalizes the work of Israeli and Orszag [M. Israeli, S.A. Orszag, Approximation of radiation boundary conditions, J. Comp. Phys. 41 (1981) 115-135] and confirms their findings when applied as a special case to one-dimensional wave propagation in an absorbing sponge. It is found that the rate of convergence of the actual solution to the target solution, with an appropriate norm, is inversely proportional to the sponge strength. A detailed analysis for acoustic wave propagation in one-dimension verifies the convergence rate given by the general theory. The exponential point-wise convergence derived by Israeli and Orszag in the high-frequency limit is recovered and found to hold over all frequencies. A weakly nonlinear analysis of the method when applied to Burgers' equation shows similar convergence properties. Three numerical examples are given to confirm the analysis: the acoustic extension of a two-dimensional time-harmonic point source, the acoustic extension of a three-dimensional initial-value problem of a sound pulse, and the introduction of unstable eigenmodes from linear stability theory into a two-dimensional shear layer
A computational fluid dynamics simulation framework for ventricular catheter design optimization.
Weisenberg, Sofy H; TerMaath, Stephanie C; Barbier, Charlotte N; Hill, Judith C; Killeffer, James A
2017-11-10
OBJECTIVE Cerebrospinal fluid (CSF) shunts are the primary treatment for patients suffering from hydrocephalus. While proven effective in symptom relief, these shunt systems are plagued by high failure rates and often require repeated revision surgeries to replace malfunctioning components. One of the leading causes of CSF shunt failure is obstruction of the ventricular catheter by aggregations of cells, proteins, blood clots, or fronds of choroid plexus that occlude the catheter's small inlet holes or even the full internal catheter lumen. Such obstructions can disrupt CSF diversion out of the ventricular system or impede it entirely. Previous studies have suggested that altering the catheter's fluid dynamics may help to reduce the likelihood of complete ventricular catheter failure caused by obstruction. However, systematic correlation between a ventricular catheter's design parameters and its performance, specifically its likelihood to become occluded, still remains unknown. Therefore, an automated, open-source computational fluid dynamics (CFD) simulation framework was developed for use in the medical community to determine optimized ventricular catheter designs and to rapidly explore parameter influence for a given flow objective. METHODS The computational framework was developed by coupling a 3D CFD solver and an iterative optimization algorithm and was implemented in a high-performance computing environment. The capabilities of the framework were demonstrated by computing an optimized ventricular catheter design that provides uniform flow rates through the catheter's inlet holes, a common design objective in the literature. The baseline computational model was validated using 3D nuclear imaging to provide flow velocities at the inlet holes and through the catheter. RESULTS The optimized catheter design achieved through use of the automated simulation framework improved significantly on previous attempts to reach a uniform inlet flow rate distribution using
Performance Evaluation of Cutting Fluids Developed from Fixed Oils
Directory of Open Access Journals (Sweden)
Emmanuel Ogo ONCHE
2007-01-01
Full Text Available In this work, different cutting fluid emulsions of about 10% concentration were developed from fixed oils and the performance of each of the developed cutting fluid was evaluated by a direct comparison with as purchased conventional cutting fluid (control sample, using the ability of each sample to effectively perform as coolant and lubricant during machining operation as determinant. In the evaluation process, straight turning operation on lathe machine at various speeds, but equal time intervals of 10 minutes was used with a 2 mm/min feed rate. It was found that cutting fluid developed from groundnut oil (Sample B performed best as coolant at all experimented speeds, with maximum temperature of 60.5° C at the working zone as against 71.39° C observed for the Control (Sample A. The viscosity 10.76 cSt of Sample B was however, higher than those of Samples A (4.79 cSt and C (6.20 cSt. It was recommended that further work be done to synergize Samples B and C and the cooling effectiveness of the hybridized cutting fluid on the tool-chip interphase, as well as its lubricity be evaluated.
Reactor physics simulations with coupled Monte Carlo calculation and computational fluid dynamics
International Nuclear Information System (INIS)
Seker, V.; Thomas, J.W.; Downar, T.J.
2007-01-01
A computational code system based on coupling the Monte Carlo code MCNP5 and the Computational Fluid Dynamics (CFD) code STAR-CD was developed as an audit tool for lower order nuclear reactor calculations. This paper presents the methodology of the developed computer program 'McSTAR'. McSTAR is written in FORTRAN90 programming language and couples MCNP5 and the commercial CFD code STAR-CD. MCNP uses a continuous energy cross section library produced by the NJOY code system from the raw ENDF/B data. A major part of the work was to develop and implement methods to update the cross section library with the temperature distribution calculated by STARCD for every region. Three different methods were investigated and implemented in McSTAR. The user subroutines in STAR-CD are modified to read the power density data and assign them to the appropriate variables in the program and to write an output data file containing the temperature, density and indexing information to perform the mapping between MCNP and STAR-CD cells. Preliminary testing of the code was performed using a 3x3 PWR pin-cell problem. The preliminary results are compared with those obtained from a STAR-CD coupled calculation with the deterministic transport code DeCART. Good agreement in the k eff and the power profile was observed. Increased computational capabilities and improvements in computational methods have accelerated interest in high fidelity modeling of nuclear reactor cores during the last several years. High-fidelity has been achieved by utilizing full core neutron transport solutions for the neutronics calculation and computational fluid dynamics solutions for the thermal-hydraulics calculation. Previous researchers have reported the coupling of 3D deterministic neutron transport method to CFD and their application to practical reactor analysis problems. One of the principal motivations of the work here was to utilize Monte Carlo methods to validate the coupled deterministic neutron transport
Quinoa - Adaptive Computational Fluid Dynamics, 0.2
Energy Technology Data Exchange (ETDEWEB)
2017-09-22
Quinoa is a set of computational tools that enables research and numerical analysis in fluid dynamics. At this time it remains a test-bed to experiment with various algorithms using fully asynchronous runtime systems. Currently, Quinoa consists of the following tools: (1) Walker, a numerical integrator for systems of stochastic differential equations in time. It is a mathematical tool to analyze and design the behavior of stochastic differential equations. It allows the estimation of arbitrary coupled statistics and probability density functions and is currently used for the design of statistical moment approximations for multiple mixing materials in variable-density turbulence. (2) Inciter, an overdecomposition-aware finite element field solver for partial differential equations using 3D unstructured grids. Inciter is used to research asynchronous mesh-based algorithms and to experiment with coupling asynchronous to bulk-synchronous parallel code. Two planned new features of Inciter, compared to the previous release (LA-CC-16-015), to be implemented in 2017, are (a) a simple Navier-Stokes solver for ideal single-material compressible gases, and (b) solution-adaptive mesh refinement (AMR), which enables dynamically concentrating compute resources to regions with interesting physics. Using the NS-AMR problem we plan to explore how to scale such high-load-imbalance simulations, representative of large production multiphysics codes, to very large problems on very large computers using an asynchronous runtime system. (3) RNGTest, a test harness to subject random number generators to stringent statistical tests enabling quantitative ranking with respect to their quality and computational cost. (4) UnitTest, a unit test harness, running hundreds of tests per second, capable of testing serial, synchronous, and asynchronous functions. (5) MeshConv, a mesh file converter that can be used to convert 3D tetrahedron meshes from and to either of the following formats: Gmsh
A computational model for thermal fluid design analysis of nuclear thermal rockets
International Nuclear Information System (INIS)
Given, J.A.; Anghaie, S.
1997-01-01
A computational model for simulation and design analysis of nuclear thermal propulsion systems has been developed. The model simulates a full-topping expander cycle engine system and the thermofluid dynamics of the core coolant flow, accounting for the real gas properties of the hydrogen propellant/coolant throughout the system. Core thermofluid studies reveal that near-wall heat transfer models currently available may not be applicable to conditions encountered within some nuclear rocket cores. Additionally, the possibility of a core thermal fluid instability at low mass fluxes and the effects of the core power distribution are investigated. Results indicate that for tubular core coolant channels, thermal fluid instability is not an issue within the possible range of operating conditions in these systems. Findings also show the advantages of having a nonflat centrally peaking axial core power profile from a fluid dynamic standpoint. The effects of rocket operating conditions on system performance are also investigated. Results show that high temperature and low pressure operation is limited by core structural considerations, while low temperature and high pressure operation is limited by system performance constraints. The utility of these programs for finding these operational limits, optimum operating conditions, and thermal fluid effects is demonstrated
Energy Technology Data Exchange (ETDEWEB)
Bowers, Geoffrey [Alfred Univ., NY (United States)
2017-04-05
United States Department of Energy grant DE-FG02-10ER16128, “Computational and Spectroscopic Investigations of the Molecular Scale Structure and Dynamics of Geologically Important Fluids and Mineral-Fluid Interfaces” (Geoffrey M. Bowers, P.I.) focused on developing a molecular-scale understanding of processes that occur in fluids and at solid-fluid interfaces using the combination of spectroscopic, microscopic, and diffraction studies with molecular dynamics computer modeling. The work is intimately tied to the twin proposal at Michigan State University (DOE DE-FG02-08ER15929; same title: R. James Kirkpatrick, P.I. and A. Ozgur Yazaydin, co-P.I.).
Improving flow distribution in influent channels using computational fluid dynamics.
Park, No-Suk; Yoon, Sukmin; Jeong, Woochang; Lee, Seungjae
2016-10-01
Although the flow distribution in an influent channel where the inflow is split into each treatment process in a wastewater treatment plant greatly affects the efficiency of the process, and a weir is the typical structure for the flow distribution, to the authors' knowledge, there is a paucity of research on the flow distribution in an open channel with a weir. In this study, the influent channel of a real-scale wastewater treatment plant was used, installing a suppressed rectangular weir that has a horizontal crest to cross the full channel width. The flow distribution in the influent channel was analyzed using a validated computational fluid dynamics model to investigate (1) the comparison of single-phase and two-phase simulation, (2) the improved procedure of the prototype channel, and (3) the effect of the inflow rate on flow distribution. The results show that two-phase simulation is more reliable due to the description of the free-surface fluctuations. It should first be considered for improving flow distribution to prevent a short-circuit flow, and the difference in the kinetic energy with the inflow rate makes flow distribution trends different. The authors believe that this case study is helpful for improving flow distribution in an influent channel.
Introducing Computational Fluid Dynamics Simulation into Olfactory Display
Ishida, Hiroshi; Yoshida, Hitoshi; Nakamoto, Takamichi
An olfactory display is a device that delivers various odors to the user's nose. It can be used to add special effects to movies and games by releasing odors relevant to the scenes shown on the screen. In order to provide high-presence olfactory stimuli to the users, the display must be able to generate realistic odors with appropriate concentrations in a timely manner together with visual and audio playbacks. In this paper, we propose to use computational fluid dynamics (CFD) simulations in conjunction with the olfactory display. Odor molecules released from their source are transported mainly by turbulent flow, and their behavior can be extremely complicated even in a simple indoor environment. In the proposed system, a CFD solver is employed to calculate the airflow field and the odor dispersal in the given environment. An odor blender is used to generate the odor with the concentration determined based on the calculated odor distribution. Experimental results on presenting odor stimuli synchronously with movie clips show the effectiveness of the proposed system.
Performances of cutting fluids in turning. Mineral oil - RM
DEFF Research Database (Denmark)
Axinte, Dragos Aurelian; Belluco, Walter
1999-01-01
Scope of the present measurement campaign is the evaluation of the cutting fluid performance. The report presents the standard routine and the results obtained when turning stainless steel and brass with a commercial vegetable based oil called RM. The methods were developed to be applicable...
Performances of cutting fluids in turning. Vegetable based oil - RV
DEFF Research Database (Denmark)
Axinte, Dragos Aurelian; Belluco, Walter
1999-01-01
Scope of the present measurement campaign is the evaluation of the cutting fluid performance. The report presents the standard routine and the results obtained when turning stainless steel and brass with a commercial vegetable based oil called RV. The methods were developed to be applicable...
Williams, R. W. (Compiler)
1996-01-01
The purpose of the workshop was to discuss experimental and computational fluid dynamic activities in rocket propulsion and launch vehicles. The workshop was an open meeting for government, industry, and academia. A broad number of topics were discussed including computational fluid dynamic methodology, liquid and solid rocket propulsion, turbomachinery, combustion, heat transfer, and grid generation.
A computational approach for fluid queues driven by truncated birth-death processes.
Lenin, R.B.; Parthasarathy, P.R.
2000-01-01
In this paper, we analyze fluid queues driven by truncated birth-death processes with general birth and death rates. We compute the equilibrium distribution of the content of the fluid buffer by providing efficient numerical procedures to compute the eigenvalues and the eigenvectors of the
Network survivability performance (computer diskette)
1993-11-01
File characteristics: Data file; 1 file. Physical description: 1 computer diskette; 3 1/2 in.; high density; 2.0MB. System requirements: Mac; Word. This technical report has been developed to address the survivability of telecommunications networks including services. It responds to the need for a common understanding of, and assessment techniques for network survivability, availability, integrity, and reliability. It provides a basis for designing and operating telecommunication networks to user expectations for network survivability.
A Computation Fluid Dynamic Model for Gas Lift Process Simulation in a Vertical Oil Well
Directory of Open Access Journals (Sweden)
Kadivar Arash
2017-03-01
Full Text Available Continuous gas-lift in a typical oil well was simulated using computational fluid dynamic (CFD technique. A multi fluid model based on the momentum transfer between liquid and gas bubbles was employed to simulate two-phase flow in a vertical pipe. The accuracy of the model was investigated through comparison of numerical predictions with experimental data. The model then was used to study the dynamic behaviour of the two-phase flow around injection point in details. The predictions by the model were compared with other empirical correlations, as well. To obtain an optimum condition of gas-lift, the influence of the effective parameters including the quantity of injected gas, tubing diameter and bubble size distribution were investigated. The results revealed that increasing tubing diameter, the injected gas rate and decreasing bubble diameter improve gas-lift performance.
Development of a Fast Fluid-Structure Coupling Technique for Wind Turbine Computations
DEFF Research Database (Denmark)
Sessarego, Matias; Ramos García, Néstor; Shen, Wen Zhong
2015-01-01
Fluid-structure interaction simulations are routinely used in the wind energy industry to evaluate the aerodynamic and structural dynamic performance of wind turbines. Most aero-elastic codes in modern times implement a blade element momentum technique to model the rotor aerodynamics and a modal......, multi-body, or finite-element approach to model the turbine structural dynamics. The present paper describes a novel fluid-structure coupling technique which combines a threedimensional viscous-inviscid solver for horizontal-axis wind-turbine aerodynamics, called MIRAS, and the structural dynamics model...... used in the aero-elastic code FLEX5. The new code, MIRASFLEX, in general shows good agreement with the standard aero-elastic codes FLEX5 and FAST for various test cases. The structural model in MIRAS-FLEX acts to reduce the aerodynamic load computed by MIRAS, particularly near the tip and at high wind...
Utilisation of computational fluid dynamics techniques for design of molybdenum target specification
International Nuclear Information System (INIS)
Yeoh, G.H.; Wassink, D.
2003-01-01
A three-dimensional computational fluid dynamics (CFD) model to investigate the hydraulic behaviour within a model of the liner and irradiation rig, located in the central portion of the HIFAR fuel element is described. Flow visualisation and LDV measurements are performed to better understand the fluid flow around the narrow spaces within the irradiation rig, annular target cans and liner. Based on the unstructured meshing consisted of triangular elements and tetrahedrons within the flow space generated for the geometrical structure, the CFD model was able to predict complex flow structures inside the liner containing the irradiation rig and target cans. The reliability of the model was validated against experiments. The predicted flow behaviour was comparable to the experimental observations. Predicted velocities were also found to be in good agreement with LDV measurements. (author)
Performance of V-type Stirling-cycle refrigerator for different working fluids
Energy Technology Data Exchange (ETDEWEB)
Tekin, Yusuf; Ataer, Omer Ercan [Erciyes University, Engineering Faculty, Mechanical Engineering Department, Melikgazi, 38 039 Kayseri (Turkey)
2010-01-15
The thermodynamic analysis of a V-type Stirling-cycle Refrigerator (VSR) is performed for air, hydrogen and helium as the working fluid and the performance of the VSR is investigated. The V-type Stirling-cycle refrigerator consists of expansion and compression spaces, cooler, heater and regenerator, and it is assumed that the control volumes are subjected to a periodic mass flow. The basic equations of the VSR are derived for per unit crank angle, so time does not appear in the equations. A computer program is prepared in FORTRAN, and the basic equations are solved iteratively. The mass, temperature and density of working fluid in each control volume are calculated for different charge pressures, engine speeds, and for fixed heater and cooler surface temperatures. The work, instantaneous pressure and the COP of the VSR are calculated. The results are obtained for different working fluids, and given by diagrams. (author)
DYNAPO 4 - a fluid system and frames analysis computer program
International Nuclear Information System (INIS)
Lefter, J.D.; Ahdout, H.
1982-01-01
DYNAPO 4 is a user oriented specialized computer program, capable of analyzing three-dimensional linear elastic piping systems or frames for static loads, dynamic loads represented by acceleration response spectra, transient dynamic loads represented by harmonic, polynomial of second order, and time history forcing functions. DYNAPO 4 has plotting capability, which plots the input configuration of the piping system or of the structure and also plots its deformed shape after the load is applied. DYNAPO 4 performs the analysis for ASME Section III Class 1, Class 2, and 3, piping, and provides the user with stress reports as per ASME and ANSI Code requirements. 3 refs
Bai, Ge; Bee, Jared S; Biddlecombe, James G; Chen, Quanmin; Leach, W Thomas
2012-02-28
Agitation of small amounts of liquid is performed routinely in biopharmaceutical process, formulation, and packaging development. Protein degradation commonly results from agitation, but the specific stress responsible or degradation mechanism is usually not well understood. Characterization of the agitation stress methods is critical to identifying protein degradation mechanisms or specific sensitivities. In this study, computational fluid dynamics (CFD) was used to model agitation of 1 mL of fluid by four types of common laboratory agitation instruments, including a rotator, orbital shaker, magnetic stirrer and vortex mixer. Fluid stresses in the bulk liquid and near interfaces were identified, quantified and compared. The vortex mixer provides the most intense stresses overall, while the stir bar system presented locally intense shear proximal to the hydrophobic stir bar surface. The rotator provides gentler fluid stresses, but the air-water interfacial area and surface stresses are relatively high given its low rotational frequency. The orbital shaker provides intermediate-level stresses but with the advantage of a large stable platform for consistent vial-to-vial homogeneity. Selection of experimental agitation methods with targeted types and intensities of stresses can facilitate better understanding of protein degradation mechanisms and predictability for "real world" applications. Copyright © 2011 Elsevier B.V. All rights reserved.
High-performance computing — an overview
Marksteiner, Peter
1996-08-01
An overview of high-performance computing (HPC) is given. Different types of computer architectures used in HPC are discussed: vector supercomputers, high-performance RISC processors, various parallel computers like symmetric multiprocessors, workstation clusters, massively parallel processors. Software tools and programming techniques used in HPC are reviewed: vectorizing compilers, optimization and vector tuning, optimization for RISC processors; parallel programming techniques like shared-memory parallelism, message passing and data parallelism; and numerical libraries.
Gas condensate reservoir performance : part 1 : fluid characterization
Energy Technology Data Exchange (ETDEWEB)
Thomas, F.B.; Bennion, D.B. [Hycal Energy Research Laboratories Ltd., Calgary, AB (Canada); Andersen, G. [ChevronTexaco, Calgary, AB (Canada)
2006-07-01
Phase behaviour in gas condensate reservoirs is sensitive to changes in pressure and temperature, which can lead to significant errors in fluid characterization. The challenging task of characterizing in situ fluids in gas condensate reservoirs was discussed with reference to the errors that occur as a result of the complex coupling between phase behavior and geology. This paper presented techniques for reservoir sampling and characterization and proposed methods for minimizing errors. Errors are often made in the classification of dew point systems because engineering criteria does not accurately represent the phase behavior of the reservoir. For example, the fluid of a certain condensate yield may be categorized as a wet gas rather than a retrograde condensate fluid. It was noted that the liquid yield does not dictate whether the fluid is condensate or wet gas, but rather where the reservoir temperature is situated in the pressure temperature phase loop. In order to proceed with a viable field development plan and optimization, the reservoir fluid must be understood. Given that gas productivity decreases with liquid drop out in the near wellbore region, capillary pressure plays a significant role in retrograde reservoirs. It was noted that well understood parameters will lead to a better assessment of the amount of hydrocarbon in place, the rate at which the resource can be produced and optimization strategies as the reservoir matures. It was concluded that multi-rate sampling is the best method to use in sampling fluids since the liquid yield changes as a function of rate. Although bottom-hole sampling in gas condensate reservoirs may be problematic, it should always be performed to address any concerns for liquid-solid separation. Produced fluids typically reveal a specific signature that informs the operator of in situ properties. This paper presented examples that pertain to wet versus retrograde condensate behavior and the presence of an oil zone. The
Computational fluid dynamics application: slosh analysis of a fuel tank model
International Nuclear Information System (INIS)
Iu, H.S.; Cleghorn, W.L.; Mills, J.K.
2004-01-01
This paper presents the analysis of fluid slosh behaviour inside a fuel tank model. The fuel tank model was a simplified version of a stock fuel tank that has a sloshing noise problem. A commercial CFD software, FLOW-3D, was used to simulate the slosh behaviour. Slosh experiments were performed to verify the computer simulation results. High speed video equipment enhanced with a data acquisition system was used to record the slosh experiments and to obtain the instantaneous sound level of each video frame. Five baffle configurations including the no baffle configuration were considered in the computer simulations and the experiments. The simulation results showed that the best baffle configuration can reduce the mean kinetic energy by 80% from the no baffle configuration in a certain slosh situation. The experimental results showed that 15dB(A) noise reduction can be achieved by the best baffle configuration. The correlation analysis between the mean kinetic energy and the noise level showed that high mean kinetic energy of the fluid does not always correspond to high sloshing noise. High correlation between them only occurs for the slosh situations where the fluid hits the top of the tank and creates noise. (author)
Computational Fluid Dynamics Model for Saltstone Vault 4 Vapor Space
International Nuclear Information System (INIS)
Lee, Si Young
2005-01-01
Computational fluid dynamics (CFD) methods have been used to estimate the flow patterns for vapor space inside the Saltstone Vault No.4 under different operating scenarios. The purpose of this work is to examine the gas motions inside the vapor space under the current vault configurations. A CFD model took three-dimensional transient momentum-energy coupled approach for the vapor space domain of the vault. The modeling calculations were based on prototypic vault geometry and expected normal operating conditions as defined by Waste Solidification Engineering. The modeling analysis was focused on the air flow patterns near the ventilated corner zones of the vapor space inside the Saltstone vault. The turbulence behavior and natural convection mechanism used in the present model were benchmarked against the literature information and theoretical results. The verified model was applied to the Saltstone vault geometry for the transient assessment of the air flow patterns inside the vapor space of the vault region using the boundary conditions as provided by the customer. The present model considered two cases for the estimations of the flow patterns within the vapor space. One is the reference baseline case. The other is for the negative temperature gradient between the roof inner and top grout surface temperatures intended for the potential bounding condition. The flow patterns of the vapor space calculated by the CFD model demonstrate that the ambient air comes into the vapor space of the vault through the lower-end ventilation hole, and it gets heated up by the Benard-cell type circulation before leaving the vault via the higher-end ventilation hole. The calculated results are consistent with the literature information
International Nuclear Information System (INIS)
Jackson, V.L.
2011-01-01
The primary purpose of the tank mixing and sampling demonstration program is to mitigate the technical risks associated with the ability of the Hanford tank farm delivery and celtification systems to measure and deliver a uniformly mixed high-level waste (HLW) feed to the Waste Treatment and Immobilization Plant (WTP) Uniform feed to the WTP is a requirement of 24590-WTP-ICD-MG-01-019, ICD-19 - Interface Control Document for Waste Feed, although the exact definition of uniform is evolving in this context. Computational Fluid Dynamics (CFD) modeling has been used to assist in evaluating scaleup issues, study operational parameters, and predict mixing performance at full-scale.
A computational method to predict fluid-structure interaction of pressure relief valves
Energy Technology Data Exchange (ETDEWEB)
Kang, S. K.; Lee, D. H.; Park, S. K.; Hong, S. R. [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
2004-07-01
An effective CFD (Computational fluid dynamics) method to predict important performance parameters, such as blowdown and chattering, for pressure relief valves in NPPs is provided in the present study. To calculate the valve motion, 6DOF (six degree of freedom) model is used. A chimera overset grid method is utilized to this study for the elimination of grid remeshing problem, when the disk moves. Further, CFD-Fastran which is developed by CFD-RC for compressible flow analysis is applied to an 1' safety valve. The prediction results ensure the applicability of the presented method in this study.
Influence of particle size distributions on magnetorheological fluid performances
International Nuclear Information System (INIS)
Chiriac, H; Stoian, G
2010-01-01
In this paper we investigate the influence that size distributions of the magnetic particles might have on the magnetorheological fluid performances. In our study, several size distributions have been tailored first by sieving a micrometric Fe powder in order to obtain narrow distribution powders and then by recomposing the new size distributions (different from Gaussian). We used spherical Fe particles (mesh -325) commercially available. The powder was sieved by means of a sieve shaker using a series of sieves with the following mesh size: 20, 32, 40, 50, 63, 80 micrometers. All magnetic powders were characterized through Vibrating Sample Magnetometer (VSM) measurements, particle size analysis and also Scanning Electron Microscope (SEM) images were taken. Magnetorheological (MR) fluids based on the resulted magnetic powders were prepared and studied by means of a rheometer with a magnetorheological module. The MR fluids were measured in magnetic field and in zero magnetic field as well. As we noticed in our previous experiments particles size distribution can also influence the MR fluids performances.
McCloud, Peter L.
2010-01-01
Thermal Protection System (TPS) Cavity Heating is predicted using Computational Fluid Dynamics (CFD) on unstructured grids for both simplified cavities and actual cavity geometries. Validation was performed using comparisons to wind tunnel experimental results and CFD predictions using structured grids. Full-scale predictions were made for simplified and actual geometry configurations on the Space Shuttle Orbiter in a mission support timeframe.
HIGH-FIDELITY SIMULATION-DRIVEN MODEL DEVELOPMENT FOR COARSE-GRAINED COMPUTATIONAL FLUID DYNAMICS
Energy Technology Data Exchange (ETDEWEB)
Hanna, Botros N.; Dinh, Nam T.; Bolotnov, Igor A.
2016-06-01
Nuclear reactor safety analysis requires identifying various credible accident scenarios and determining their consequences. For a full-scale nuclear power plant system behavior, it is impossible to obtain sufficient experimental data for a broad range of risk-significant accident scenarios. In single-phase flow convective problems, Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) can provide us with high fidelity results when physical data are unavailable. However, these methods are computationally expensive and cannot be afforded for simulation of long transient scenarios in nuclear accidents despite extraordinary advances in high performance scientific computing over the past decades. The major issue is the inability to make the transient computation parallel, thus making number of time steps required in high-fidelity methods unaffordable for long transients. In this work, we propose to apply a high fidelity simulation-driven approach to model sub-grid scale (SGS) effect in Coarse Grained Computational Fluid Dynamics CG-CFD. This approach aims to develop a statistical surrogate model instead of the deterministic SGS model. We chose to start with a turbulent natural convection case with volumetric heating in a horizontal fluid layer with a rigid, insulated lower boundary and isothermal (cold) upper boundary. This scenario of unstable stratification is relevant to turbulent natural convection in a molten corium pool during a severe nuclear reactor accident, as well as in containment mixing and passive cooling. The presented approach demonstrates how to create a correction for the CG-CFD solution by modifying the energy balance equation. A global correction for the temperature equation proves to achieve a significant improvement to the prediction of steady state temperature distribution through the fluid layer.
Kumar, K. Ravi; Cheepu, Muralimohan; Srinivas, B.; Venkateswarlu, D.; Pramod Kumar, G.; Shiva, Apireddi
2018-03-01
In solar air heater, artificial roughness on absorber plate become prominent technique to improving heat transfer rate of air flowing passage as a result of laminar sublayer. The selection of rib geometries plays important role on friction characteristics and heat transfer rate. Many researchers studying the roughness shapes over the years to investigate the effect of geometries on the performance of friction factor and heat transfer of the solar air heater. The present study made an attempt to develop the different rib shapes utilised for creating artificial rib roughness and its comparison to investigate higher performance of the geometries. The use of computational fluid dynamics software resulted in correlation of friction factor and heat transfer rate. The simulations studies were performed on 2D computational fluid dynamics model and analysed to identify the most effective parameters of relative roughness of the height, width and pitch on major considerations of friction factor and heat transfer. The Reynolds number is varied in a range from 3000 to 20000, in the current study and modelling has conducted on heat transfer and turbulence phenomena by using Reynolds number. The modelling results showed the formation of strong vortex in the main stream flow due to the right angle triangle roughness over the square, rectangle, improved rectangle and equilateral triangle geometries enhanced the heat transfer extension in the solar air heater. The simulation of the turbulence kinetic energy of the geometry suggests the local turbulence kinetic energy has been influenced strongly by the alignments of the right angle triangle.
US QCD computational performance studies with PERI
International Nuclear Information System (INIS)
Zhang, Y; Fowler, R; Huck, K; Malony, A; Porterfield, A; Reed, D; Shende, S; Taylor, V; Wu, X
2007-01-01
We report on some of the interactions between two SciDAC projects: The National Computational Infrastructure for Lattice Gauge Theory (USQCD), and the Performance Engineering Research Institute (PERI). Many modern scientific programs consistently report the need for faster computational resources to maintain global competitiveness. However, as the size and complexity of emerging high end computing (HEC) systems continue to rise, achieving good performance on such systems is becoming ever more challenging. In order to take full advantage of the resources, it is crucial to understand the characteristics of relevant scientific applications and the systems these applications are running on. Using tools developed under PERI and by other performance measurement researchers, we studied the performance of two applications, MILC and Chroma, on several high performance computing systems at DOE laboratories. In the case of Chroma, we discuss how the use of C++ and modern software engineering and programming methods are driving the evolution of performance tools
Complex fluids in biological systems experiment, theory, and computation
2015-01-01
This book serves as an introduction to the continuum mechanics and mathematical modeling of complex fluids in living systems. The form and function of living systems are intimately tied to the nature of surrounding fluid environments, which commonly exhibit nonlinear and history dependent responses to forces and displacements. With ever-increasing capabilities in the visualization and manipulation of biological systems, research on the fundamental phenomena, models, measurements, and analysis of complex fluids has taken a number of exciting directions. In this book, many of the world’s foremost experts explore key topics such as: Macro- and micro-rheological techniques for measuring the material properties of complex biofluids and the subtleties of data interpretation Experimental observations and rheology of complex biological materials, including mucus, cell membranes, the cytoskeleton, and blood The motility of microorganisms in complex fluids and the dynamics of active suspensions Challenges and solut...
Computational fluid dynamics analysis of a mixed flow pump impeller
African Journals Online (AJOL)
ATHARVA
International Journal of Engineering, Science and Technology ... From the CFD analysis software and advanced post processing tools the complex flow inside the ... The numerical simulation can provide quite accurate information on the fluid ...
1992-01-01
Research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, numerical analysis, fluid mechanics including fluid dynamics, acoustics, and combustion, aerodynamics, and computer science during the period 1 Apr. 1992 - 30 Sep. 1992 is summarized.
Williams, R. W. (Compiler)
1996-01-01
This conference publication includes various abstracts and presentations given at the 13th Workshop for Computational Fluid Dynamic Applications in Rocket Propulsion and Launch Vehicle Technology held at the George C. Marshall Space Flight Center April 25-27 1995. The purpose of the workshop was to discuss experimental and computational fluid dynamic activities in rocket propulsion and launch vehicles. The workshop was an open meeting for government, industry, and academia. A broad number of topics were discussed including computational fluid dynamic methodology, liquid and solid rocket propulsion, turbomachinery, combustion, heat transfer, and grid generation.
Computational fluid-dynamic model of laser-induced breakdown in air
International Nuclear Information System (INIS)
Dors, Ivan G.; Parigger, Christian G.
2003-01-01
Temperature and pressure profiles are computed by the use of a two-dimensional, axially symmetric, time-accurate computational fluid-dynamic model for nominal 10-ns optical breakdown laser pulses. The computational model includes a kinetics mechanism that implements plasma equilibrium kinetics in ionized regions and nonequilibrium, multistep, finite-rate reactions in nonionized regions. Fluid-physics phenomena following laser-induced breakdown are recorded with high-speed shadowgraph techniques. The predicted fluid phenomena are shown by direct comparison with experimental records to agree with the flow patterns that are characteristic of laser spark decay
Ishii, Katsuya
2011-08-01
This issue includes a special section on computational fluid dynamics (CFD) in memory of the late Professor Kunio Kuwahara, who passed away on 15 September 2008, at the age of 66. In this special section, five articles are included that are based on the lectures and discussions at `The 7th International Nobeyama Workshop on CFD: To the Memory of Professor Kuwahara' held in Tokyo on 23 and 24 September 2009. Professor Kuwahara started his research in fluid dynamics under Professor Imai at the University of Tokyo. His first paper was published in 1969 with the title 'Steady Viscous Flow within Circular Boundary', with Professor Imai. In this paper, he combined theoretical and numerical methods in fluid dynamics. Since that time, he made significant and seminal contributions to computational fluid dynamics. He undertook pioneering numerical studies on the vortex method in 1970s. From then to the early nineties, he developed numerical analyses on a variety of three-dimensional unsteady phenomena of incompressible and compressible fluid flows and/or complex fluid flows using his own supercomputers with academic and industrial co-workers and members of his private research institute, ICFD in Tokyo. In addition, a number of senior and young researchers of fluid mechanics around the world were invited to ICFD and the Nobeyama workshops, which were held near his villa, and they intensively discussed new frontier problems of fluid physics and fluid engineering at Professor Kuwahara's kind hospitality. At the memorial Nobeyama workshop held in 2009, 24 overseas speakers presented their papers, including the talks of Dr J P Boris (Naval Research Laboratory), Dr E S Oran (Naval Research Laboratory), Professor Z J Wang (Iowa State University), Dr M Meinke (RWTH Aachen), Professor K Ghia (University of Cincinnati), Professor U Ghia (University of Cincinnati), Professor F Hussain (University of Houston), Professor M Farge (École Normale Superieure), Professor J Y Yong (National
Computational Fluid Dynamics Modeling of a Lithium/Thionyl Chloride Battery with Electrolyte Flow
Energy Technology Data Exchange (ETDEWEB)
Gu, W.B.; Jungst, Rudolph G.; Nagasubramanian, Ganesan; Wang, C.Y.; Weidner, John.
1999-06-11
A two-dimensional model is developed to simulate discharge of a lithium/thionyl chloride primary battery. The model accounts for not only transport of species and charge, but also the electrode porosity variations and the electrolyte flow induced by the volume reduction caused by electrochemical reactions. Numerical simulations are performed using a finite volume method of computational fluid dynamics. The predicted discharge curves for various temperatures are compared to the experimental data with excellent agreement. Moreover, the simulation results. in conjunction with computer visualization and animation techniques, confirm that cell utilization in the temperature and current range of interest is limited by pore plugging or clogging of the front side of the cathode as a result of LiCl precipitation. The detailed two-dimensional flow simulation also shows that the electrolyte is replenished from the cell header predominantly through the separator into the front of the cathode during most parts of the discharge, especially for higher cell temperatures.
International Nuclear Information System (INIS)
2005-01-01
The Thirteenth Annual Conference of the Computational Fluid Dynamics Society of Canada, CFD 2005, was held in St. John's, Newfoundland from July 31 to August 3, 2005. The conference covers a variety of disciplines, including hydrodynamics, aerodynamics/aero-acoustics/aero-elasticity, combustion and heat transfer, hydrology, automotive, nuclear and other industrial application areas. Flows considered include non-Newtonian and multiphase flows, subsonic, supersonic and hypersonic flows, cavitating flows, free-surface flows, jet flows, vortex flows, detonation flows, plasma arc flows and porous media flows. A major theme of these flows is turbulence, and there are many papers that consider Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES), although Reynolds Averaged Navier-Stokes methods remain popular. There is a strong interest in high performance computing (HPC) because of the increased throughput it affords. Flow visualization and post processing is also highlighted in many papers
International Nuclear Information System (INIS)
Scott, B.; Jenko, F.; Peeters, A.G.; Teo, A.C.Y.
1999-01-01
(1) Computations of turbulence from the electromagnetic gyro fluid model are performed in a flux surface geometry representing the actual MHD equilibrium of the ASDEX Upgrade edge flux surfaces. The transition to ideal ballooning seen in simple geometries as the plasma beta rises is suppressed, leaving the transport at quantitatively realistic levels. Computations for core parameters at half-radius geometry show significant contribution due to the finite beta electron dynamics, possibly removing the standard ITG threshold. (2) Strong inward vorticity transport in edge turbulence, resulting from ion diamagnetic flows, may lead to a build up of mean ExB vorticity fast enough to cause an H-mode transition. (3) Friction of mean ion flows against neutrals involves both toroidal and poloidal flow components, leading to a finite radial current due to a given ExB profile even with zero poloidal rotation. (author)
Wiputra, Hadi; Lai, Chang Quan; Lim, Guat Ling; Heng, Joel Jia Wei; Guo, Lan; Soomar, Sanah Merchant; Leo, Hwa Liang; Biwas, Arijit; Mattar, Citra Nurfarah Zaini; Yap, Choon Hwai
2016-12-01
There are 0.6-1.9% of US children who were born with congenital heart malformations. Clinical and animal studies suggest that abnormal blood flow forces might play a role in causing these malformation, highlighting the importance of understanding the fetal cardiovascular fluid mechanics. We performed computational fluid dynamics simulations of the right ventricles, based on four-dimensional ultrasound scans of three 20-wk-old normal human fetuses, to characterize their flow and energy dynamics. Peak intraventricular pressure gradients were found to be 0.2-0.9 mmHg during systole, and 0.1-0.2 mmHg during diastole. Diastolic wall shear stresses were found to be around 1 Pa, which could elevate to 2-4 Pa during systole in the outflow tract. Fetal right ventricles have complex flow patterns featuring two interacting diastolic vortex rings, formed during diastolic E wave and A wave. These rings persisted through the end of systole and elevated wall shear stresses in their proximity. They were observed to conserve ∼25.0% of peak diastolic kinetic energy to be carried over into the subsequent systole. However, this carried-over kinetic energy did not significantly alter the work done by the heart for ejection. Thus, while diastolic vortexes played a significant role in determining spatial patterns and magnitudes of diastolic wall shear stresses, they did not have significant influence on systolic ejection. Our results can serve as a baseline for future comparison with diseased hearts. Copyright © 2016 the American Physiological Society.
Debugging a high performance computing program
Gooding, Thomas M.
2013-08-20
Methods, apparatus, and computer program products are disclosed for debugging a high performance computing program by gathering lists of addresses of calling instructions for a plurality of threads of execution of the program, assigning the threads to groups in dependence upon the addresses, and displaying the groups to identify defective threads.
Performance of a viscous damper using electro-rheological fluid
International Nuclear Information System (INIS)
Otani, A.; Kobayashi, H.; Kobayashi, N.; Tadaishi, Y.
1994-01-01
A new damper has been developed that suppresses small-amplitude vibrations over a wide frequency range. The damper has been tested using both an electro-rheological fluid (ERF) and a highly viscous liquid, which are enclosed in the damper's casing (a metal bellows). The apparent viscosity of the ERF can be changed by varying the strength of the applied electrical field. Initially, a simple L-shaped piping model excited by a rotary-type exciter was used to investigate the performance of the damper, utilizing both fluids. The experimental results demonstrate the effectiveness of the passive damper. Based on the experimental results, application of the damper to an actual piping system with a big pump was carried out analytical
Embedded High Performance Scalable Computing Systems
National Research Council Canada - National Science Library
Ngo, David
2003-01-01
The Embedded High Performance Scalable Computing Systems (EHPSCS) program is a cooperative agreement between Sanders, A Lockheed Martin Company and DARPA that ran for three years, from Apr 1995 - Apr 1998...
Cloud Computing for Complex Performance Codes.
Energy Technology Data Exchange (ETDEWEB)
Appel, Gordon John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hadgu, Teklu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Klein, Brandon Thorin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Miner, John Gifford [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-02-01
This report describes the use of cloud computing services for running complex public domain performance assessment problems. The work consisted of two phases: Phase 1 was to demonstrate complex codes, on several differently configured servers, could run and compute trivial small scale problems in a commercial cloud infrastructure. Phase 2 focused on proving non-trivial large scale problems could be computed in the commercial cloud environment. The cloud computing effort was successfully applied using codes of interest to the geohydrology and nuclear waste disposal modeling community.
Revisiting Newtonian and Non-Newtonian Fluid Mechanics Using Computer Algebra
Knight, D. G.
2006-01-01
This article illustrates how a computer algebra system, such as Maple[R], can assist in the study of theoretical fluid mechanics, for both Newtonian and non-Newtonian fluids. The continuity equation, the stress equations of motion, the Navier-Stokes equations, and various constitutive equations are treated, using a full, but straightforward,…
A computational approach for a fluid queue driven by a truncated birth-death process
Lenin, R.B.; Parthasarathy, P.R.
1999-01-01
In this paper, we consider a fluid queue driven by a truncated birth-death process with general birth and death rates. We find the equilibrium distribution of the content of the fluid buffer by computing the eigenvalues and eigenvectors of an associated real tridiagonal matrix. We provide efficient
Computer program TMOC for calculating of pressure transients in fluid filled piping networks
International Nuclear Information System (INIS)
Siikonen, T.
1978-01-01
The propagation of a pressure wave in fluid filles tubes is significantly affected by the pipe wall motion and vice versa. A computer code TMOC (Transients by the Method of Characteristics) is being developed for the analysis of the coupled fluid and pipe wall transients. Because of the structural feedback, the pressure can be calculated more accurately than in the programs commonly used. (author)
Computational fluid mechanics qualification calculations for the code TEACH
International Nuclear Information System (INIS)
DeGrazia, M.C.; Fitzsimmons, L.B.; Reynolds, J.T.
1979-11-01
KAPL is developing a predictive method for three-dimensional (3-D) turbulent fluid flow configurations typically encountered in the thermal-hydraulic design of a nuclear reactor. A series of experiments has been selected for analysis to investigate the adequacy of the two-equation turbulence model developed at Imperial College, London, England for predicting the flow patterns in simple geometries. The analysis of these experiments is described with the two-dimensional (2-D) turbulent fluid flow code TEACH. This work qualifies TEACH for a variety of geometries and flow conditions
A non-oscillatory energy-splitting method for the computation of compressible multi-fluid flows
Lei, Xin; Li, Jiequan
2018-04-01
This paper proposes a new non-oscillatory energy-splitting conservative algorithm for computing multi-fluid flows in the Eulerian framework. In comparison with existing multi-fluid algorithms in the literature, it is shown that the mass fraction model with isobaric hypothesis is a plausible choice for designing numerical methods for multi-fluid flows. Then we construct a conservative Godunov-based scheme with the high order accurate extension by using the generalized Riemann problem solver, through the detailed analysis of kinetic energy exchange when fluids are mixed under the hypothesis of isobaric equilibrium. Numerical experiments are carried out for the shock-interface interaction and shock-bubble interaction problems, which display the excellent performance of this type of schemes and demonstrate that nonphysical oscillations are suppressed around material interfaces substantially.
Computational Fluid Dynamic (CFD) Analysis of a Generic Missile With Grid Fins
National Research Council Canada - National Science Library
DeSpirito, James
2000-01-01
This report presents the results of a study demonstrating an approach for using viscous computational fluid dynamic simulations to calculate the flow field and aerodynamic coefficients for a missile with grid fin...
An Adaptive Middleware for Improved Computational Performance
DEFF Research Database (Denmark)
Bonnichsen, Lars Frydendal
, we are improving computational performance by exploiting modern hardware features, such as dynamic voltage-frequency scaling and transactional memory. Adapting software is an iterative process, requiring that we continually revisit it to meet new requirements or realities; a time consuming process......The performance improvements in computer systems over the past 60 years have been fueled by an exponential increase in energy efficiency. In recent years, the phenomenon known as the end of Dennard’s scaling has slowed energy efficiency improvements — but improving computer energy efficiency...... is more important now than ever. Traditionally, most improvements in computer energy efficiency have come from improvements in lithography — the ability to produce smaller transistors — and computer architecture - the ability to apply those transistors efficiently. Since the end of scaling, we have seen...
Erosion Evaluation of a Slurry Mixer Tank with Computational Fluid Dynamics Methods
International Nuclear Information System (INIS)
Lee, S
2006-01-01
This paper discusses the use of computational fluid dynamics (CFD) methods to understand and characterize erosion of the floor and internal structures in the slurry mixing vessels in the Defense Waste Processing Facility. An initial literature survey helped identify the principal drivers of erosion for a solids laden fluid: the solids content of the working fluid, the regions of recirculation and particle impact with the walls, and the regions of high wall shear. A series of CFD analyses was performed to characterize slurry-flow profiles, wall shear, and particle impingement distributions in key components such as coil restraints and the vessel floor. The calculations showed that the primary locations of high erosion resulting from abrasion were at the leading edge of the coil guide, the tank floor below the insert plate of the coil guide support, and the upstream lead-in plate. These modeling results based on the calculated high shear regions were in excellent agreement with the observed erosion sites in both location and the degree of erosion. Loss of the leading edge of the coil guide due to the erosion damage during the slurry mixing operation did not affect the erosion patterns on the tank floor. Calculations for a lower impeller speed showed similar erosion patterns but significantly reduced wall shear stresses
DEFF Research Database (Denmark)
Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan
is vital. Multi-criteria database search and Computer Aided Molecular Design(CAMD) can be applied to generate, test and evaluate promising pure component/mixture candidate as process fluids to help optimize cycle design and performance. The problem formulation for the development of novel working fluids...... is anadvanced CAMD challenge both in terms of data and computational demand, because includes process related as wellas property related equations.In CAMD problems the identification of target properties is often based on expert knowledge. To support identification of relevant target properties, in this study...... allows the ranking ofsignificance of properties and also the identification of a set of properties which are relevant for the design of a workingfluids.In this study the CAMD problem for the development of novel working fluids for organic Rankine cycles (ORC) isformulated as a mathematical optimization...
International Nuclear Information System (INIS)
Kirkpatrick, R. James; Kalinichev, Andrey G.
2008-01-01
Research supported by this grant focuses on molecular scale understanding of central issues related to the structure and dynamics of geochemically important fluids, fluid-mineral interfaces, and confined fluids using computational modeling and experimental methods. Molecular scale knowledge about fluid structure and dynamics, how these are affected by mineral surfaces and molecular-scale (nano-) confinement, and how water molecules and dissolved species interact with surfaces is essential to understanding the fundamental chemistry of a wide range of low-temperature geochemical processes, including sorption and geochemical transport. Our principal efforts are devoted to continued development of relevant computational approaches, application of these approaches to important geochemical questions, relevant NMR and other experimental studies, and application of computational modeling methods to understanding the experimental results. The combination of computational modeling and experimental approaches is proving highly effective in addressing otherwise intractable problems. In 2006-2007 we have significantly advanced in new, highly promising research directions along with completion of on-going projects and final publication of work completed in previous years. New computational directions are focusing on modeling proton exchange reactions in aqueous solutions using ab initio molecular dynamics (AIMD), metadynamics (MTD), and empirical valence bond (EVB) approaches. Proton exchange is critical to understanding the structure, dynamics, and reactivity at mineral-water interfaces and for oxy-ions in solution, but has traditionally been difficult to model with molecular dynamics (MD). Our ultimate objective is to develop this capability, because MD is much less computationally demanding than quantum-chemical approaches. We have also extended our previous MD simulations of metal binding to natural organic matter (NOM) to a much longer time scale (up to 10 ns) for
Steam generator transient studies using a simplified two-fluid computer code
International Nuclear Information System (INIS)
Munshi, P.; Bhatnagar, R.; Ram, K.S.
1985-01-01
A simplified two-fluid computer code has been used to simulate reactor-side (or primary-side) transients in a PWR steam generator. The disturbances are modelled as ramp inputs for pressure, internal energy and mass flow-rate for the primary fluid. The CPU time for a transient duration of 4 s is approx. 10 min on a DEC-1090 computer system. The results are thermodynamically consistent and encouraging for further studies. (author)
1994-01-01
This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period October 1, 1993 through March 31, 1994. The major categories of the current ICASE research program are: (1) applied and numerical mathematics, including numerical analysis and algorithm development; (2) theoretical and computational research in fluid mechanics in selected areas of interest to LaRC, including acoustics and combustion; (3) experimental research in transition and turbulence and aerodynamics involving LaRC facilities and scientists; and (4) computer science.
Reactor physics simulations with coupled Monte Carlo calculation and computational fluid dynamics
International Nuclear Information System (INIS)
Seker, V.; Thomas, J. W.; Downar, T. J.
2007-01-01
The interest in high fidelity modeling of nuclear reactor cores has increased over the last few years and has become computationally more feasible because of the dramatic improvements in processor speed and the availability of low cost parallel platforms. In the research here high fidelity, multi-physics analyses was performed by solving the neutron transport equation using Monte Carlo methods and by solving the thermal-hydraulics equations using computational fluid dynamics. A computation tool based on coupling the Monte Carlo code MCNP5 and the Computational Fluid Dynamics (CFD) code STAR-CD was developed as an audit tool for lower order nuclear reactor calculations. This paper presents the methodology of the developed computer program 'McSTAR' along with the verification and validation efforts. McSTAR is written in PERL programming language and couples MCNP5 and the commercial CFD code STAR-CD. MCNP uses a continuous energy cross section library produced by the NJOY code system from the raw ENDF/B data. A major part of the work was to develop and implement methods to update the cross section library with the temperature distribution calculated by STAR-CD for every region. Three different methods were investigated and two of them are implemented in McSTAR. The user subroutines in STAR-CD are modified to read the power density data and assign them to the appropriate variables in the program and to write an output data file containing the temperature, density and indexing information to perform the mapping between MCNP and STAR-CD cells. The necessary input file manipulation, data file generation, normalization and multi-processor calculation settings are all done through the program flow in McSTAR. Initial testing of the code was performed using a single pin cell and a 3X3 PWR pin-cell problem. The preliminary results of the single pin-cell problem are compared with those obtained from a STAR-CD coupled calculation with the deterministic transport code De
Reagan, Andrew J; Dubief, Yves; Dodds, Peter Sheridan; Danforth, Christopher M
2016-01-01
A thermal convection loop is a annular chamber filled with water, heated on the bottom half and cooled on the top half. With sufficiently large forcing of heat, the direction of fluid flow in the loop oscillates chaotically, dynamics analogous to the Earth's weather. As is the case for state-of-the-art weather models, we only observe the statistics over a small region of state space, making prediction difficult. To overcome this challenge, data assimilation (DA) methods, and specifically ensemble methods, use the computational model itself to estimate the uncertainty of the model to optimally combine these observations into an initial condition for predicting the future state. Here, we build and verify four distinct DA methods, and then, we perform a twin model experiment with the computational fluid dynamics simulation of the loop using the Ensemble Transform Kalman Filter (ETKF) to assimilate observations and predict flow reversals. We show that using adaptively shaped localized covariance outperforms static localized covariance with the ETKF, and allows for the use of less observations in predicting flow reversals. We also show that a Dynamic Mode Decomposition (DMD) of the temperature and velocity fields recovers the low dimensional system underlying reversals, finding specific modes which together are predictive of reversal direction.
Directory of Open Access Journals (Sweden)
Andrew J Reagan
Full Text Available A thermal convection loop is a annular chamber filled with water, heated on the bottom half and cooled on the top half. With sufficiently large forcing of heat, the direction of fluid flow in the loop oscillates chaotically, dynamics analogous to the Earth's weather. As is the case for state-of-the-art weather models, we only observe the statistics over a small region of state space, making prediction difficult. To overcome this challenge, data assimilation (DA methods, and specifically ensemble methods, use the computational model itself to estimate the uncertainty of the model to optimally combine these observations into an initial condition for predicting the future state. Here, we build and verify four distinct DA methods, and then, we perform a twin model experiment with the computational fluid dynamics simulation of the loop using the Ensemble Transform Kalman Filter (ETKF to assimilate observations and predict flow reversals. We show that using adaptively shaped localized covariance outperforms static localized covariance with the ETKF, and allows for the use of less observations in predicting flow reversals. We also show that a Dynamic Mode Decomposition (DMD of the temperature and velocity fields recovers the low dimensional system underlying reversals, finding specific modes which together are predictive of reversal direction.
Fluid forces enhance the performance of an aspirant leader in self-organized living groups.
Directory of Open Access Journals (Sweden)
Alessandro De Rosis
Full Text Available In this paper, the performance of an individual aiming at guiding a self-organized group is numerically investigated. A collective behavioural model is adopted, accounting for the mutual repulsion, attraction and orientation experienced by the individuals. Moreover, these represent a set of solid particles which are supposed to be immersed in a fictitious viscous fluid. In particular, the lattice Boltzmann and Immersed boundary methods are used to predict the fluid dynamics, whereas the effect of the hydrodynamic forces on particles is accounted for by solving the equation of the solid motion through the time discontinuous Galerkin scheme. Numerical simulations are carried out by involving the individuals in a dichotomous process. On the one hand, an aspirant leader (AL additional individual is added to the system. AL is forced to move along a prescribed direction which intersects the group. On the other hand, these tend to depart from an obstacle represented by a rotating lamina which is placed in the fluid domain. A numerical campaign is carried out by varying the fluid viscosity and, as a consequence, the hydrodynamic field. Moreover, scenarios characterized by different values of the size of the group are investigated. In order to estimate the AL's performance, a proper parameter is introduced, depending on the number of individuals following AL. Present findings show that the sole collective behavioural equations are insufficient to predict the AL's performance, since the motion is drastically affected by the presence of the surrounding fluid. With respect to the existing literature, the proposed numerical model is enriched by accounting for the presence of the encompassing fluid, thus computing the hydrodynamic forces arising when the individuals move.
Function Follows Performance in Evolutionary Computational Processing
DEFF Research Database (Denmark)
Pasold, Anke; Foged, Isak Worre
2011-01-01
As the title ‘Function Follows Performance in Evolutionary Computational Processing’ suggests, this paper explores the potentials of employing multiple design and evaluation criteria within one processing model in order to account for a number of performative parameters desired within varied...
Sesti, Erika L.; Alaniva, Nicholas; Rand, Peter W.; Choi, Eric J.; Albert, Brice J.; Saliba, Edward P.; Scott, Faith J.; Barnes, Alexander B.
2018-01-01
We report magic angle spinning (MAS) up to 8.5 kHz with a sample temperature below 6 K using liquid helium as a variable temperature fluid. Cross polarization 13C NMR spectra exhibit exquisite sensitivity with a single transient. Remarkably, 1H saturation recovery experiments show a 1H T1 of 21 s with MAS below 6 K in the presence of trityl radicals in a glassy matrix. Leveraging the thermal spin polarization available at 4.2 K versus 298 K should result in 71 times higher signal intensity. Taking the 1H longitudinal relaxation into account, signal averaging times are therefore predicted to be expedited by a factor of >500. Computer assisted design (CAD) and finite element analysis were employed in both the design and diagnostic stages of this cryogenic MAS technology development. Computational fluid dynamics (CFD) models describing temperature gradients and fluid flow are presented. The CFD models bearing and drive gas maintained at 100 K, while a colder helium variable temperature fluid stream cools the center of a zirconia rotor. Results from the CFD were used to optimize the helium exhaust path and determine the sample temperature. This novel cryogenic experimental platform will be integrated with pulsed dynamic nuclear polarization and electron decoupling to interrogate biomolecular structure within intact human cells.
Shaded computer graphic techniques for visualizing and interpreting analytic fluid flow models
Parke, F. I.
1981-01-01
Mathematical models which predict the behavior of fluid flow in different experiments are simulated using digital computers. The simulations predict values of parameters of the fluid flow (pressure, temperature and velocity vector) at many points in the fluid. Visualization of the spatial variation in the value of these parameters is important to comprehend and check the data generated, to identify the regions of interest in the flow, and for effectively communicating information about the flow to others. The state of the art imaging techniques developed in the field of three dimensional shaded computer graphics is applied to visualization of fluid flow. Use of an imaging technique known as 'SCAN' for visualizing fluid flow, is studied and the results are presented.
Computer simulations of magnetic fluids in laminar pipe flows
International Nuclear Information System (INIS)
Ramos, D.M.; Cunha, F.R.; Sobral, Y.D.; Fontoura Rodrigues, J.L.A.
2005-01-01
Finite volume method is adapted to simulate momentum and magnetic coupled equations of a laminar magnetic fluid flow. An evolution equation is used to calculate the fluid magnetization. Pressure-driven flow under steady and oscillatory magnetic field is investigated. The magnetostatic limit of the Maxwell's equations is treated in terms of a Poisson equation numerically integrated. The SIMPLE algorithm is used to calculate the pressure-velocity coupling when the pressure field is not prescribed. Suitable boundary conditions for velocity, magnetization and field intensity on the pipe wall are described. Results are obtained for velocity and pressure response under several conditions of the identified physical parameters of the flow. The simulations are verified by comparing numerical results and asymptotic theory, and they show a very good agreement
Applications of automatic differentiation in computational fluid dynamics
Green, Lawrence L.; Carle, A.; Bischof, C.; Haigler, Kara J.; Newman, Perry A.
1994-01-01
Automatic differentiation (AD) is a powerful computational method that provides for computing exact sensitivity derivatives (SD) from existing computer programs for multidisciplinary design optimization (MDO) or in sensitivity analysis. A pre-compiler AD tool for FORTRAN programs called ADIFOR has been developed. The ADIFOR tool has been easily and quickly applied by NASA Langley researchers to assess the feasibility and computational impact of AD in MDO with several different FORTRAN programs. These include a state-of-the-art three dimensional multigrid Navier-Stokes flow solver for wings or aircraft configurations in transonic turbulent flow. With ADIFOR the user specifies sets of independent and dependent variables with an existing computer code. ADIFOR then traces the dependency path throughout the code, applies the chain rule to formulate derivative expressions, and generates new code to compute the required SD matrix. The resulting codes have been verified to compute exact non-geometric and geometric SD for a variety of cases. in less time than is required to compute the SD matrix using centered divided differences.
Ex vivo characterization of pathologic fluids with quantitative phase-contrast computed tomography
Energy Technology Data Exchange (ETDEWEB)
Richter, Vivien, E-mail: vivien.richter@med.uni-tuebingen.de [Department of Diagnostic and Interventional Radiology, Eberhard Karls Universität Tübingen, Hoppe-Seyler-Weg 3, 72076 Tuebingen (Germany); Willner, Marian S., E-mail: marian.willner@ph.tum.de [Department of Physics & Institute of Medical Engineering, Technische Universität München, James-Franck-Strasse 1, 85748 Garching (Germany); Henningsen, John, E-mail: john.henningsen@tum.de [Department of Physics & Institute of Medical Engineering, Technische Universität München, James-Franck-Strasse 1, 85748 Garching (Germany); Birnbacher, Lorenz, E-mail: lorenz.birnbacher@ph.tum.de [Department of Physics & Institute of Medical Engineering, Technische Universität München, James-Franck-Strasse 1, 85748 Garching (Germany); Marschner, Mathias, E-mail: mathias.marschner@ph.tum.de [Department of Physics & Institute of Medical Engineering, Technische Universität München, James-Franck-Strasse 1, 85748 Garching (Germany); Herzen, Julia, E-mail: julia.herzen@ph.tum.de [Department of Physics & Institute of Medical Engineering, Technische Universität München, James-Franck-Strasse 1, 85748 Garching (Germany); Kimm, Melanie A., E-mail: melanie.kimm@tum.de [Department of Diagnostic and Interventional Radiology, Technische Universität München, Ismaninger Str. 22, 81675 Munich (Germany); and others
2017-01-15
Purpose: X-ray phase-contrast imaging (PCI) provides additional information beyond absorption characteristics by detecting the phase shift of the X-ray beam passing through material. The grating-based system works with standard polychromatic X-ray sources, promising a possible clinical implementation. PCI has been shown to provide additional information in soft-tissue samples. The aim of this study was to determine if ex vivo quantitative phase-contrast computed tomography (PCCT) may differentiate between pathologic fluid collections. Materials and methods: PCCT was performed with the grating interferometry method. A protein serial dilution, human blood samples and 17 clinical samples of pathologic fluid retentions were imaged and correlated with clinical chemistry measurements. Conventional and phase-contrast tomography images were reconstructed. Phase-contrast Hounsfield Units (HUp) were used for quantitative analysis analogously to conventional HU. The imaging was analyzed using overall means, ROI values as well as whole-volume-histograms and vertical gradients. Contrast to noise ratios were calculated between different probes and between imaging methods. Results: HUp showed a very good linear correlation with protein concentration in vitro. In clinical samples, HUp correlated rather well with cell count and triglyceride content. PCI was better than absorption imaging at differentiating protein concentrations in the protein samples as well as at differentiating blood plasma from cellular components. PCI also allowed for differentiation of watery samples (such as lymphoceles) from pus. Conclusion: Phase-contrast computed tomography is a promising tool for the differentiation of pathologic fluids that appear homogenous with conventional attenuation imaging.
AHPCRC - Army High Performance Computing Research Center
2010-01-01
computing. Of particular interest is the ability of a distrib- uted jamming network (DJN) to jam signals in all or part of a sensor or communications net...and reasoning, assistive technologies. FRIEDRICH (FRITZ) PRINZ Finmeccanica Professor of Engineering, Robert Bosch Chair, Department of Engineering...High Performance Computing Research Center www.ahpcrc.org BARBARA BRYAN AHPCRC Research and Outreach Manager, HPTi (650) 604-3732 bbryan@hpti.com Ms
DURIP: High Performance Computing in Biomathematics Applications
2017-05-10
Mathematics and Statistics (AMS) at the University of California, Santa Cruz (UCSC) to conduct research and research-related education in areas of...Computing in Biomathematics Applications Report Title The goal of this award was to enhance the capabilities of the Department of Applied Mathematics and...DURIP: High Performance Computing in Biomathematics Applications The goal of this award was to enhance the capabilities of the Department of Applied
Description of a general method to compute the fluid-structure interaction
International Nuclear Information System (INIS)
Jeanpierre, F.; Gibert, R.J.; Hoffmann, A.; Livolant, M.
1979-01-01
The vibrational characteristics of a structure in air may be considerably modified when the structure is immersed in a dense fluid. Such fluid structure interaction effects are important for the seismic or flow induced vibrational studies of various nuclear equipments, as for example the PWR internals, the fast reactor vessels, heat exchangers and fuel elements. In some simple situations, the fluid effects can be simulate by added masses, but in general, they are much more complicated. A general formulation to calculate precisely the vibrational behaviour of structures containing dense fluids is presented in this paper. That formulation can be easily introduced in finite elements computer codes, the fluid being described by special fluid elements. Its use is in principle limited to the linear range: small movements of structures, small pressure fluctuations. (orig.)
A Fluid Model for Performance Analysis in Cellular Networks
Directory of Open Access Journals (Sweden)
Coupechoux Marceau
2010-01-01
Full Text Available We propose a new framework to study the performance of cellular networks using a fluid model and we derive from this model analytical formulas for interference, outage probability, and spatial outage probability. The key idea of the fluid model is to consider the discrete base station (BS entities as a continuum of transmitters that are spatially distributed in the network. This model allows us to obtain simple analytical expressions to reveal main characteristics of the network. In this paper, we focus on the downlink other-cell interference factor (OCIF, which is defined for a given user as the ratio of its outer cell received power to its inner cell received power. A closed-form formula of the OCIF is provided in this paper. From this formula, we are able to obtain the global outage probability as well as the spatial outage probability, which depends on the location of a mobile station (MS initiating a new call. Our analytical results are compared to Monte Carlo simulations performed in a traditional hexagonal network. Furthermore, we demonstrate an application of the outage probability related to cell breathing and densification of cellular networks.
Computer technique for evaluating collimator performance
International Nuclear Information System (INIS)
Rollo, F.D.
1975-01-01
A computer program has been developed to theoretically evaluate the overall performance of collimators used with radioisotope scanners and γ cameras. The first step of the program involves the determination of the line spread function (LSF) and geometrical efficiency from the fundamental parameters of the collimator being evaluated. The working equations can be applied to any plane of interest. The resulting LSF is applied to subroutine computer programs which compute corresponding modulation transfer function and contrast efficiency functions. The latter function is then combined with appropriate geometrical efficiency data to determine the performance index function. The overall computer program allows one to predict from the physical parameters of the collimator alone how well the collimator will reproduce various sized spherical voids of activity in the image plane. The collimator performance program can be used to compare the performance of various collimator types, to study the effects of source depth on collimator performance, and to assist in the design of collimators. The theory of the collimator performance equation is discussed, a comparison between the experimental and theoretical LSF values is made, and examples of the application of the technique are presented
Computational Fluid Dynamics of Whole-Body Aircraft
Agarwal, Ramesh
1999-01-01
The current state of the art in computational aerodynamics for whole-body aircraft flowfield simulations is described. Recent advances in geometry modeling, surface and volume grid generation, and flow simulation algorithms have led to accurate flowfield predictions for increasingly complex and realistic configurations. As a result, computational aerodynamics has emerged as a crucial enabling technology for the design and development of flight vehicles. Examples illustrating the current capability for the prediction of transport and fighter aircraft flowfields are presented. Unfortunately, accurate modeling of turbulence remains a major difficulty in the analysis of viscosity-dominated flows. In the future, inverse design methods, multidisciplinary design optimization methods, artificial intelligence technology, and massively parallel computer technology will be incorporated into computational aerodynamics, opening up greater opportunities for improved product design at substantially reduced costs.
Analytical, Computational Fluid Dynamics and Flight Dynamics of Coandă MAV
Djojodihardjo, H.; Ahmed, RI
2016-11-01
The paper establishes the basic working relationships among various relevant variables and parameters governing the aerodynamics forces and performance measures of Coandă MAV in hover and translatory motion. With such motivation, capitalizing on the basic fundamental principles, the Fluid Dynamics and Flight Mechanics of semi-spherical Coandă MAV configurations are revisited and analyzed as a baseline. To gain better understanding on the principle of Coandă MAV lift generation, a mathematical model for a spherical Coandă MAV is developed and analyzed from first physical principles. To gain further insight into the prevailing flow field around a Coandă MAV, as well as to verify the theoretical prediction presented in the work, a computational fluid dynamic CFD simulation for a Coandă MAV generic model are elaborated using commercial software FLUENT®. In addition, the equation of motion for translatory motion of Coandă MAV is elaborated. The mathematical model and derived performance measures are shown to be capable in describing the physical phenomena of the flow field of the semi-spherical Coandă MAV. The relationships between the relevant parameters of the mathematical model of the Coandă MAV to the forces acting on it are elaborated subsequently.
Teaching Computer-Aided Design of Fluid Flow and Heat Transfer Engineering Equipment.
Gosman, A. D.; And Others
1979-01-01
Describes a teaching program for fluid mechanics and heat transfer which contains both computer aided learning (CAL) and computer aided design (CAD) components and argues that the understanding of the physical and numerical modeling taught in the CAL course is essential to the proper implementation of CAD. (Author/CMV)
Misleading Performance Claims in Parallel Computations
Energy Technology Data Exchange (ETDEWEB)
Bailey, David H.
2009-05-29
In a previous humorous note entitled 'Twelve Ways to Fool the Masses,' I outlined twelve common ways in which performance figures for technical computer systems can be distorted. In this paper and accompanying conference talk, I give a reprise of these twelve 'methods' and give some actual examples that have appeared in peer-reviewed literature in years past. I then propose guidelines for reporting performance, the adoption of which would raise the level of professionalism and reduce the level of confusion, not only in the world of device simulation but also in the larger arena of technical computing.
Computation of the effect of pipe plasticity on pressure-pulse propagation in a fluid system
International Nuclear Information System (INIS)
Youngdahl, C.K.; Kot, C.A.
1975-04-01
A simple computational model is developed for incorporating the effect of elastic-plastic deformation of piping on pressure-transient propagation in a fluid system. A computer program (PLWV) is described that incorporates this structural interaction model into a one-dimensional method-of-characteristics procedure for fluid-hammer analysis. Computed results are shown to be in good agreement with available experimental data. The most significant effect of plastic deformation is to limit the peak pressure of a pulse leaving a pipe to approximately the yield pressure of the pipe, if the pipe is sufficiently long. 7 references. (U.S.)
2nd International Conference on Multiscale Computational Methods for Solids and Fluids
2016-01-01
This volume contains the best papers presented at the 2nd ECCOMAS International Conference on Multiscale Computations for Solids and Fluids, held June 10-12, 2015. Topics dealt with include multiscale strategy for efficient development of scientific software for large-scale computations, coupled probability-nonlinear-mechanics problems and solution methods, and modern mathematical and computational setting for multi-phase flows and fluid-structure interaction. The papers consist of contributions by six experts who taught short courses prior to the conference, along with several selected articles from other participants dealing with complementary issues, covering both solid mechanics and applied mathematics. .
A. Mahammedi; H. Ameur; A. Ariss
2017-01-01
The laminar flow of non-Newtonian fluids through a Kenics static mixer is investigated by using the CFD (Computational Fluid Dynamics) tool. The working fluids have a shear thinning behavior modeled by the Ostwald De Waele law. We focus on the effect of Reynolds number, fluid properties, twist angle and blade pitch on the flow characteristics and energy cost. The pressure drop information obtained from the simulations was compared to several experimental correlations and data available in the...
B. Koren (Barry); M.R. Lewis; E.H. van Brummelen (Harald); B. van Leer
2001-01-01
textabstractA finite-volume method is presented for the computation of compressible flows of two immiscible fluids at very different densities. The novel ingredient in the method is a two-fluid linearized Godunov scheme, allowing for flux computations in case of different fluids (e.g., water and
High-performance computing for airborne applications
International Nuclear Information System (INIS)
Quinn, Heather M.; Manuzatto, Andrea; Fairbanks, Tom; Dallmann, Nicholas; Desgeorges, Rose
2010-01-01
Recently, there has been attempts to move common satellite tasks to unmanned aerial vehicles (UAVs). UAVs are significantly cheaper to buy than satellites and easier to deploy on an as-needed basis. The more benign radiation environment also allows for an aggressive adoption of state-of-the-art commercial computational devices, which increases the amount of data that can be collected. There are a number of commercial computing devices currently available that are well-suited to high-performance computing. These devices range from specialized computational devices, such as field-programmable gate arrays (FPGAs) and digital signal processors (DSPs), to traditional computing platforms, such as microprocessors. Even though the radiation environment is relatively benign, these devices could be susceptible to single-event effects. In this paper, we will present radiation data for high-performance computing devices in a accelerated neutron environment. These devices include a multi-core digital signal processor, two field-programmable gate arrays, and a microprocessor. From these results, we found that all of these devices are suitable for many airplane environments without reliability problems.
Computational fluid dynamics modeling of mixed convection flows in buildings enclosures
Energy Technology Data Exchange (ETDEWEB)
Kayne, Alexander; Agarwal, Ramesh K. [Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States)
2013-07-01
In recent years Computational Fluid Dynamics (CFD) simulations are increasingly used to model the air circulation and temperature environment inside the rooms of residential and office buildings to gain insight into the relative energy consumptions of various HVAC systems for cooling/heating for climate control and thermal comfort. This requires accurate simulation of turbulent flow and heat transfer for various types of ventilation systems using the Reynolds-Averaged Navier-Stokes (RANS) equations of fluid dynamics. Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) of Navier-Stokes equations is computationally intensive and expensive for simulations of this kind. As a result, vast majority of CFD simulations employ RANS equations in conjunction with a turbulence model. In order to assess the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for accurate simulations, it is critical to validate the calculations against the experimental data. For this purpose, we use three well known benchmark validation cases, one for natural convection in 2D closed vertical cavity, second for forced convection in a 2D rectangular cavity and the third for mixed convection in a 2D square cavity. The simulations are performed on a number of meshes of different density using a number of turbulence models. It is found that k-epsilon two-equation turbulence model with a second-order algorithm on a reasonable mesh gives the best results. This information is then used to determine the modeling requirements (mesh, numerical algorithm, turbulence model etc.) for flows in 3D enclosures with different ventilation systems. In particular two cases are considered for which the experimental data is available. These cases are (1) air flow and heat transfer in a naturally ventilated room and (2) airflow and temperature distribution in an atrium. Good agreement with the experimental data and computations of other investigators is obtained.
Computational Fluid Dynamics Modeling of the Human Pulmonary Arteries with Experimental Validation.
Bordones, Alifer D; Leroux, Matthew; Kheyfets, Vitaly O; Wu, Yu-An; Chen, Chia-Yuan; Finol, Ender A
2018-05-21
Pulmonary hypertension (PH) is a chronic progressive disease characterized by elevated pulmonary arterial pressure, caused by an increase in pulmonary arterial impedance. Computational fluid dynamics (CFD) can be used to identify metrics representative of the stage of PH disease. However, experimental validation of CFD models is often not pursued due to the geometric complexity of the model or uncertainties in the reproduction of the required flow conditions. The goal of this work is to validate experimentally a CFD model of a pulmonary artery phantom using a particle image velocimetry (PIV) technique. Rapid prototyping was used for the construction of the patient-specific pulmonary geometry, derived from chest computed tomography angiography images. CFD simulations were performed with the pulmonary model with a Reynolds number matching those of the experiments. Flow rates, the velocity field, and shear stress distributions obtained with the CFD simulations were compared to their counterparts from the PIV flow visualization experiments. Computationally predicted flow rates were within 1% of the experimental measurements for three of the four branches of the CFD model. The mean velocities in four transversal planes of study were within 5.9 to 13.1% of the experimental mean velocities. Shear stresses were qualitatively similar between the two methods with some discrepancies in the regions of high velocity gradients. The fluid flow differences between the CFD model and the PIV phantom are attributed to experimental inaccuracies and the relative compliance of the phantom. This comparative analysis yielded valuable information on the accuracy of CFD predicted hemodynamics in pulmonary circulation models.
Gao, Xi; Kong, Bo; Vigil, R Dennis
2017-01-01
A comprehensive quantitative model incorporating the effects of fluid flow patterns, light distribution, and algal growth kinetics on biomass growth rate is developed in order to predict the performance of a Taylor vortex algal photobioreactor for culturing Chlorella vulgaris. A commonly used Lagrangian strategy for coupling the various factors influencing algal growth was employed whereby results from computational fluid dynamics and radiation transport simulations were used to compute numerous microorganism light exposure histories, and this information in turn was used to estimate the global biomass specific growth rate. The simulations provide good quantitative agreement with experimental data and correctly predict the trend in reactor performance as a key reactor operating parameter is varied (inner cylinder rotation speed). However, biomass growth curves are consistently over-predicted and potential causes for these over-predictions and drawbacks of the Lagrangian approach are addressed. Copyright © 2016 Elsevier Ltd. All rights reserved.
A substructure method to compute the 3D fluid-structure interaction during blowdown
International Nuclear Information System (INIS)
Guilbaud, D.; Axisa, F.; Gantenbein, F.; Gibert, R.J.
1983-08-01
The waves generated by a sudden rupture of a PWR primary pipe have an important mechanical effect on the internal structures of the vessel. This fluid-structure interaction has a strong 3D aspect. 3D finite element explicit methods can be applied. These methods take into account the non linearities of the problem but the calculation is heavy and expensive. We describe in this paper another type of method based on a substructure procedure: the vessel, internals and contained fluid are axisymmetrically described (AQUAMODE computer code). The pipes and contained fluid are monodimensionaly described (TEDEL-FLUIDE Computer Code). These substructures are characterized by their natural modes. Then, they are connected to another (connection of both structural and fluid nodes) the TRISTANA Computer Code. This method allows to compute correctly and cheaply the 3D fluid-structure effects. The treatment of certain non linearities is difficult because of the modal characterization of the substructures. However variations of contact conditions versus time can be introduced. We present here some validation tests and comparison with experimental results of the litterature
International Nuclear Information System (INIS)
Kubo, S; Ishioka, T; Fukutomi, J; Shigemitsu, T
2012-01-01
Fluid machines for fluid food have been used in wide variety of fields i.e. transportation, the filling, and for the improvement of quality of fluid foods. However, flow conditions of it are quite complicated because fluid foods are different from water. Therefore, design methods based on internal flow conditions have not been conducted. In this research, turbo-pumps having a small number of blades were used to decrease shear loss and keep wide flow passage. The influence of the tip clearance was investigated by the numerical analysis using the model with and without the tip clearance. In this paper, the influence of tip clearance on performances and internal flow conditions of turbo-pump using low viscous fluid were clarified by experimental and numerical analysis results. In addition, design methods based on the internal flow were considered. Further, the influences of viscosity on the performance characteristic and internal flow were investigated.
Pool boiling performance of NovecTM 649 engineered fluid
International Nuclear Information System (INIS)
Forrest, Eric; Buongiorno, Jacopo; McKrell, Thomas; Hu, Lin-Wen
2009-01-01
A new fluorinated ketone, C 2 F 5 C(O)CF(CF 3 ) 2 , is currently being considered as an environmentally friendly alternative for power electronics cooling applications due to its high dielectric strength and low global warming potential (GWP). Sold commercially by the 3M Company as Novec TM 649 Engineered Fluid, C 2 F 5 C(O)CF(CF 3 ) 2 exhibits very low acute toxicity while maintaining long-term stability. To assess the general two-phase heat transfer performance of Novec TM 649, pool boiling tests were conducted by resistively heating a 0.01 in. diameter nickel wire at the fluid's atmospheric saturation temperature of 49 deg C. The nucleate boiling heat transfer coefficient and critical heat flux (CHF) obtained for the fluorinated ketone compare favorably with results obtained for FC-72, a fluorocarbon widely used for the direct cooling of electronic devices. Initial results indicate that Novec TM 649 may prove to be a viable alternative to FC-72 and other halo alkanes for the cooling of high power density electronic devices. (author)
Dong, Shuhao; Zhu, Ping; Xu, Xiaoying; Li, Sha; Jiang, Yongxiang; Xu, Hong
2015-07-01
Agitator is one of the essential factors to realize high efficient fermentation for high aerobic and viscous microorganisms, and the influence of different impeller combination on the fermentation process is very important. Welan gum is a microbial exopolysaccharide produced by Alcaligenes sp. under high aerobic and high viscos conditions. Computational fluid dynamics (CFD) numerical simulation was used for analyzing the distribution of velocity, shear rate and gas holdup in the welan fermentation reactor under six different impeller combinations. The best three combinations of impellers were applied to the fermentation of welan. By analyzing the fermentation performance, the MB-4-6 combination had better effect on dissolved oxygen and velocity. The content of welan was increased by 13%. Furthermore, the viscosity of production were also increased.
Computational fluid dynamics modeling of a lithium/thionyl chloride battery with electrolyte flow
Energy Technology Data Exchange (ETDEWEB)
Gu, W.B.; Wang, C.Y.; Weidner, J.W.; Jungst, R.G.; Nagasubramanian, G.
2000-02-01
A two-dimensional model is developed to simulate discharge of a lithium/thionyl chloride primary battery. As in earlier one-dimensional models, the model accounts for transport of species and charge, and electrode porosity variations and electrolyte flow induced by the volume reduction caused by electrochemical reactions. Numerical simulations are performed using a finite volume method of computational fluid dynamics. The predicted discharge curves for various temperatures show good agreement with published experimental data, and are essentially identical to results published for one-dimensional models. The detailed two-dimensional flow simulations show that the electrolyte is replenished from the cell head space predominantly through the separator into the front of the cathode during most parts of the discharge, especially for higher cell temperatures.
Cinbiz, Mahmut N; Tığli, R Seda; Beşkardeş, Işil Gerçek; Gümüşderelioğlu, Menemşe; Colak, Uner
2010-11-01
In this study, computational fluid dynamics (CFD) analysis of a rotating-wall perfused-vessel (RWPV) bioreactor is performed to characterize the complex hydrodynamic environment for the simulation of cartilage development in RWPV bioreactor in the presence of tissue-engineered cartilage constructs, i.e., cell-chitosan scaffolds. Shear stress exerted on chitosan scaffolds in bioreactor was calculated for different rotational velocities in the range of 33-38 rpm. According to the calculations, the lateral and lower surfaces were exposed to 0.07926-0.11069 dyne/cm(2) and 0.05974-0.08345 dyne/cm(2), respectively, while upper surfaces of constructs were exposed to 0.09196-0.12847 dyne/cm(2). Results validate adequate hydrodynamic environment for scaffolds in RWPV bioreactor for cartilage tissue development which concludes the suitability of operational conditions of RWPV bioreactor. Copyright © 2010 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Zhou, Chenn
2008-01-01
Pulverized coal injection (PCI) into the blast furnace (BF) has been recognized as an effective way to decrease the coke and total energy consumption along with minimization of environmental impacts. However, increasing the amount of coal injected into the BF is currently limited by the lack of knowledge of some issues related to the process. It is therefore important to understand the complex physical and chemical phenomena in the PCI process. Due to the difficulty in attaining trus BF measurements, Computational fluid dynamics (CFD) modeling has been identified as a useful technology to provide such knowledge. CFD simulation is powerful for providing detailed information on flow properties and performing parametric studies for process design and optimization. In this project, comprehensive 3-D CFD models have been developed to simulate the PCI process under actual furnace conditions. These models provide raceway size and flow property distributions. The results have provided guidance for optimizing the PCI process
Multi-scale high-performance fluid flow: Simulations through porous media
Perović, Nevena
2016-08-03
Computational fluid dynamic (CFD) calculations on geometrically complex domains such as porous media require high geometric discretisation for accurately capturing the tested physical phenomena. Moreover, when considering a large area and analysing local effects, it is necessary to deploy a multi-scale approach that is both memory-intensive and time-consuming. Hence, this type of analysis must be conducted on a high-performance parallel computing infrastructure. In this paper, the coupling of two different scales based on the Navier–Stokes equations and Darcy\\'s law is described followed by the generation of complex geometries, and their discretisation and numerical treatment. Subsequently, the necessary parallelisation techniques and a rather specific tool, which is capable of retrieving data from the supercomputing servers and visualising them during the computation runtime (i.e. in situ) are described. All advantages and possible drawbacks of this approach, together with the preliminary results and sensitivity analyses are discussed in detail.
Multi-scale high-performance fluid flow: Simulations through porous media
Perović, Nevena; Frisch, Jé rô me; Salama, Amgad; Sun, Shuyu; Rank, Ernst; Mundani, Ralf Peter
2016-01-01
Computational fluid dynamic (CFD) calculations on geometrically complex domains such as porous media require high geometric discretisation for accurately capturing the tested physical phenomena. Moreover, when considering a large area and analysing local effects, it is necessary to deploy a multi-scale approach that is both memory-intensive and time-consuming. Hence, this type of analysis must be conducted on a high-performance parallel computing infrastructure. In this paper, the coupling of two different scales based on the Navier–Stokes equations and Darcy's law is described followed by the generation of complex geometries, and their discretisation and numerical treatment. Subsequently, the necessary parallelisation techniques and a rather specific tool, which is capable of retrieving data from the supercomputing servers and visualising them during the computation runtime (i.e. in situ) are described. All advantages and possible drawbacks of this approach, together with the preliminary results and sensitivity analyses are discussed in detail.
High performance parallel computers for science
International Nuclear Information System (INIS)
Nash, T.; Areti, H.; Atac, R.; Biel, J.; Cook, A.; Deppe, J.; Edel, M.; Fischler, M.; Gaines, I.; Hance, R.
1989-01-01
This paper reports that Fermilab's Advanced Computer Program (ACP) has been developing cost effective, yet practical, parallel computers for high energy physics since 1984. The ACP's latest developments are proceeding in two directions. A Second Generation ACP Multiprocessor System for experiments will include $3500 RISC processors each with performance over 15 VAX MIPS. To support such high performance, the new system allows parallel I/O, parallel interprocess communication, and parallel host processes. The ACP Multi-Array Processor, has been developed for theoretical physics. Each $4000 node is a FORTRAN or C programmable pipelined 20 Mflops (peak), 10 MByte single board computer. These are plugged into a 16 port crossbar switch crate which handles both inter and intra crate communication. The crates are connected in a hypercube. Site oriented applications like lattice gauge theory are supported by system software called CANOPY, which makes the hardware virtually transparent to users. A 256 node, 5 GFlop, system is under construction
Computational modeling for fluid flow and interfacial transport
Shyy, Wei
2006-01-01
Practical applications and examples highlight this treatment of computational modeling for handling complex flowfields. A reference for researchers and graduate students of many different backgrounds, it also functions as a text for learning essential computation elements.Drawing upon his own research, the author addresses both macroscopic and microscopic features. He begins his three-part treatment with a survey of the basic concepts of finite difference schemes for solving parabolic, elliptic, and hyperbolic partial differential equations. The second part concerns issues related to computati
Overview of Computational Fluid Dynamics (CFD) simulation of stirred vessel
International Nuclear Information System (INIS)
Mohd Rizal Mamat; Azraf Azman; Anwar Abdul Rahman; Noraishah Othman
2010-01-01
Stirred vessel is one of many widely used equipment in industrial process and chemical industry. The design of stirred vessel typically follows a certain standard chemical engineering practice that may also involve empirical data acquired from experiments. However the design may still take a different route which is computational engineering simulation and analysis. CFD has been identified as one of the possible tools for such purposes. CFD enables the flow fields variables such as velocity, temperature and pressure in the whole computational domain to be obtained and as such it presents an advantage over the experimental setup. (author)
Romani, Xiana; Nirschl, Hermann
2010-01-01
Centrifugal separation equipment, such as solid bowl centrifuges, is used to carry out an effective separation of fine particles from industrial fluids. Knowledge of the streams and sedimentation behavior inside solid bowl centrifuges is necessary to determine the geometry and the process parameters that lead to an optimal performance. Regarding a given industrial centrifuge geometry, a grid was built to calculate numerically the multiphase flow of water, air, and particles with a computation...
Park, Soonchan; Lee, Sang-Wook; Lim, Ok Kyun; Min, Inki; Nguyen, Minhtuan; Ko, Young Bae; Yoon, Kyunghwan; Suh, Dae Chul
2013-01-01
Purpose Image-based computational models with fluid-structure interaction (FSI) can be used to perform plaque mechanical analysis in intracranial artery stenosis. We described a process in FSI study applied to symptomatic severe intracranial (M1) stenosis before and after stenting. Materials and Methods Reconstructed 3D angiography in STL format was transferred to Magics for smoothing of vessel surface and trimming of branch vessels and to HyperMesh for generating tetra volume mesh from trian...
Performative Computation-aided Design Optimization
Directory of Open Access Journals (Sweden)
Ming Tang
2012-12-01
Full Text Available This article discusses a collaborative research and teaching project between the University of Cincinnati, Perkins+Will’s Tech Lab, and the University of North Carolina Greensboro. The primary investigation focuses on the simulation, optimization, and generation of architectural designs using performance-based computational design approaches. The projects examine various design methods, including relationships between building form, performance and the use of proprietary software tools for parametric design.
International Nuclear Information System (INIS)
Oliveira, Andre Felipe da Silva de
2012-01-01
Safety is one of the most important and desirable characteristics in a nuclear plant Natural circulation cooling systems are noted for providing passive safety. These systems can be used as mechanism for removing the residual heat from the reactor, or even as the main cooling system for heated sections, such as the core. In this work, a computational fluid dynamics (CFD) code called CFX is used to simulate the process of natural circulation in a research reactor pool after its shutdown. The physical model studied is similar to the Open Pool Australian Light water reactor (OPAL), and contains the core, cooling pool, reflecting tank, circulation pipes and chimney. For best computing performance, the core region was modeled as a porous medium, where the parameters were obtained from a separately detailed CFD analysis. This work also aims to study the viability of the implementation of Differential Evolution algorithm for optimization the physical and operational parameters that, obeying the laws of similarity, lead to a test section on a reduced scale of the reactor pool.
High performance computing on vector systems
Roller, Sabine
2008-01-01
Presents the developments in high-performance computing and simulation on modern supercomputer architectures. This book covers trends in hardware and software development in general and specifically the vector-based systems and heterogeneous architectures. It presents innovative fields like coupled multi-physics or multi-scale simulations.
Multiscale Space-Time Computational Methods for Fluid-Structure Interactions
2015-09-13
thermo-fluid analysis of a ground vehicle and its tires ST-SI Computational Analysis of a Vertical - Axis Wind Turbine We have successfully...of a vertical - axis wind turbine . Multiscale Compressible-Flow Computation with Particle Tracking We have successfully tested the multiscale...Tezduyar, Spenser McIntyre, Nikolay Kostov, Ryan Kolesar, Casey Habluetzel. Space–time VMS computation of wind - turbine rotor and tower aerodynamics
Computational fluid mechanics in R and D on uranium enrichment
International Nuclear Information System (INIS)
Soubbaramayer, O.
1988-01-01
Uranium enrichment represents an essential link in the cycle of nuclear fuels for power production. There are many processes of uranium enrichment, but three of them dominate the nuclear history as well in the past (Gaseous diffusion and centrifugation) as in the present (Laser process). The important role played by the Numerical Fluid Mechanics in the three processes is pointed out. The type of problem raised by Gaseous Diffusion is Channel Flow with wall suction, by Centrifugation, flow of a Compressible gas in a strongly rotating cylinder (Stewartson and Ekman layers) and by Laser process, Thermocapillary-buoyancy flow of a molten metal in an evaporation crucible. The methods and results in these problems are reviewed. 18 refs, 11 figs
Using Computational Fluid Dynamics to examine airflow characteristics in Empty Nose Syndrome
Flint, Tim; Esmaily-Moghadam, Mahdi; Thamboo, Andrew; Velasquez, Nathalia; Nayak, Jayakar V.; Sellier, Mathieu; Moin, Parviz
2016-11-01
The enigmatic disorder, empty nose syndrome (ENS), presents with a complex subjective symptom profile despite objectively patent nasal airways, and recent reports suggest that surgical augmentation of the nasal airway can improve quality of life and ENS-related complaints. In this study, computational fluid dynamics (CFD) was performed both prior to, and following, inferior turbinate augmentation to model the resultant changes in airflow patterns and better understand the pathophysiology of ENS. An ENS patient with marked reduction in ENS symptoms following turbinate augmentation was identified, and pre- and post-operative CT imaging was collected. A Finite element framework with the variational multiscale method (Esmaily-Moghadam, Comput. Methods Appl. Mech. Engrg. 2015) was used to compute the airflow, temperature, and moisture transport through the nasal cavity. Comparison of the CFD results following corrective surgery showed higher levels of airflow turbulence. Augmentation produced 50%, 25%, and 25% increases in root mean square pressure, wall shear stress, and heat flux respectively. These results provide insight into the changes in nasal airflow characteristics attainable through surgical augmentation, and by extension, how nasal airflow patterns may be distorted in the 'overly patent' airway of ENS patients. Supported by Stanford University CTR and Fulbright New Zealand.
Computational fluid dynamics simulations and validations of results
CSIR Research Space (South Africa)
Sitek, MA
2013-09-01
Full Text Available Wind flow influence on a high-rise building is analyzed. The research covers full-scale tests, wind-tunnel experiments and numerical simulations. In the present paper computational model used in simulations is described and the results, which were...
Fluid Mechanics of a High Performance Racing Bicycle Wheel
Mercat, Jean-Pierre; Cretoux, Brieuc; Huat, Francois-Xavier; Nordey, Benoit; Renaud, Maxime; Noca, Flavio
2013-11-01
In 2012, MAVIC released the most aerodynamic bicycle wheel on the market, the CXR 80. The french company MAVIC has been a world leader for many decades in the manufacturing of bicycle wheels for competitive events such as the Olympic Games and the Tour de France. Since 2010, MAVIC has been in a research partnership with the University of Applied Sciences in Geneva, Switzerland, for the aerodynamic development of bicycle wheels. While most of the development up to date has been performed in a classical wind tunnel, recent work has been conducted in an unusual setting, a hydrodynamic towing tank, in order to achieve low levels of turbulence and facilitate quantitative flow visualization (PIV). After a short introduction on the aerodynamics of bicycle wheels, preliminary fluid mechanics results based on this novel setup will be presented.
Lattice Boltzmann computation of creeping fluid flow in roll-coating applications
Rajan, Isac; Kesana, Balashanker; Perumal, D. Arumuga
2018-04-01
Lattice Boltzmann Method (LBM) has advanced as a class of Computational Fluid Dynamics (CFD) methods used to solve complex fluid systems and heat transfer problems. It has ever-increasingly attracted the interest of researchers in computational physics to solve challenging problems of industrial and academic importance. In this current study, LBM is applied to simulate the creeping fluid flow phenomena commonly encountered in manufacturing technologies. In particular, we apply this novel method to simulate the fluid flow phenomena associated with the "meniscus roll coating" application. This prevalent industrial problem encountered in polymer processing and thin film coating applications is modelled as standard lid-driven cavity problem to which creeping flow analysis is applied. This incompressible viscous flow problem is studied in various speed ratios, the ratio of upper to lower lid speed in two different configurations of lid movement - parallel and anti-parallel wall motion. The flow exhibits interesting patterns which will help in design of roll coaters.
A Finite-Volume computational mechanics framework for multi-physics coupled fluid-stress problems
International Nuclear Information System (INIS)
Bailey, C; Cross, M.; Pericleous, K.
1998-01-01
Where there is a strong interaction between fluid flow, heat transfer and stress induced deformation, it may not be sufficient to solve each problem separately (i.e. fluid vs. stress, using different techniques or even different computer codes). This may be acceptable where the interaction is static, but less so, if it is dynamic. It is desirable for this reason to develop software that can accommodate both requirements (i.e. that of fluid flow and that of solid mechanics) in a seamless environment. This is accomplished in the University of Greenwich code PHYSICA, which solves both the fluid flow problem and the stress-strain equations in a unified Finite-Volume environment, using an unstructured computational mesh that can deform dynamically. Example applications are given of the work of the group in the metals casting process (where thermal stresses cause elasto- visco-plastic distortion)
High-performance computing in seismology
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-09-01
The scientific, technical, and economic importance of the issues discussed here presents a clear agenda for future research in computational seismology. In this way these problems will drive advances in high-performance computing in the field of seismology. There is a broad community that will benefit from this work, including the petroleum industry, research geophysicists, engineers concerned with seismic hazard mitigation, and governments charged with enforcing a comprehensive test ban treaty. These advances may also lead to new applications for seismological research. The recent application of high-resolution seismic imaging of the shallow subsurface for the environmental remediation industry is an example of this activity. This report makes the following recommendations: (1) focused efforts to develop validated documented software for seismological computations should be supported, with special emphasis on scalable algorithms for parallel processors; (2) the education of seismologists in high-performance computing technologies and methodologies should be improved; (3) collaborations between seismologists and computational scientists and engineers should be increased; (4) the infrastructure for archiving, disseminating, and processing large volumes of seismological data should be improved.
High performance computing in linear control
International Nuclear Information System (INIS)
Datta, B.N.
1993-01-01
Remarkable progress has been made in both theory and applications of all important areas of control. The theory is rich and very sophisticated. Some beautiful applications of control theory are presently being made in aerospace, biomedical engineering, industrial engineering, robotics, economics, power systems, etc. Unfortunately, the same assessment of progress does not hold in general for computations in control theory. Control Theory is lagging behind other areas of science and engineering in this respect. Nowadays there is a revolution going on in the world of high performance scientific computing. Many powerful computers with vector and parallel processing have been built and have been available in recent years. These supercomputers offer very high speed in computations. Highly efficient software, based on powerful algorithms, has been developed to use on these advanced computers, and has also contributed to increased performance. While workers in many areas of science and engineering have taken great advantage of these hardware and software developments, control scientists and engineers, unfortunately, have not been able to take much advantage of these developments
Mccarty, R. D.
1980-01-01
The thermodynamic and transport properties of selected cryogens had programmed into a series of computer routines. Input variables are any two of P, rho or T in the single phase regions and either P or T for the saturated liquid or vapor state. The output is pressure, density, temperature, entropy, enthalpy for all of the fluids and in most cases specific heat capacity and speed of sound. Viscosity and thermal conductivity are also given for most of the fluids. The programs are designed for access by remote terminal; however, they have been written in a modular form to allow the user to select either specific fluids or specific properties for particular needs. The program includes properties for hydrogen, helium, neon, nitrogen, oxygen, argon, and methane. The programs include properties for gaseous and liquid states usually from the triple point to some upper limit of pressure and temperature which varies from fluid to fluid.
International Nuclear Information System (INIS)
Sbragio, Ricardo
1999-01-01
The determination of natural frequencies and displacement Power Spectrum Density (PSD) of fuel rods in a fluid using Computational Fluid Dynamics and Finite Element Methods is presented. The rods are modeled as slender beams subjected to small displacements in a fluid using three-dimensional mesh. The incompressible Navier-Stokes and linear momentum balance equations are solved simultaneously using Spectrum code. Two examples from literature are analyzed. The first consists in one rod in a fluid. The excitation is an impulse force at the rod central node. The second example is a two rod system in a fluid. In this case, the excitation force is random and is determined from a PSD. (author)
Anderson, Kevin R.; Zayas, Daniel; Turner, Daniel
2012-01-01
Computational Fluid Dynamics (CFD) using the commercial CFD package CFDesign has been performed at NASA Jet Propulsion Laboratory (JPL) California Institute of Technology (Caltech) in support of the Phaeton Early Career Hire Program's Optical Payload for Lasercomm Science (OPALS) mission. The OPALS project is one which involves an International Space Station payload that will be using forced convection cooling in a hermetically sealed enclosure at 1 atm of air to cool "off-the-shelf" vendor electronics. The CFD analysis was used to characterize the thermal and fluid flow environment within a complicated labyrinth of electronics boards, fans, instrumentation, harnessing, ductwork and heat exchanger fins. The paradigm of iteratively using CAD/CAE tools and CFD was followed in order to determine the optimum flow geometry and heat sink configuration to yield operational convective film coefficients and temperature survivability limits for the electronics payload. Results from this current CFD analysis and correlation of the CFD model against thermal test data will be presented. Lessons learned and coupled thermal / flow modeling strategies will be shared in this paper.
Directory of Open Access Journals (Sweden)
M. S. Najiha
2012-12-01
Full Text Available This paper presents a two-dimensional steady-state incompressible analysis for the minimum quantity of lubricant flow in milling operations using a computational fluid dynamics (CFD approach. The analysis of flow and heat transfer in a four-teeth milling cutter operation was undertaken. The domain of the rotating cutter along with the spray nozzle is defined. Operating cutting and boundary conditions are taken from the literature. A steady-state, pressure-based, planar analysis was performed with a viscous, realizable k-ε model. A mixture of oils and air were sprayed on the tool, which is considered to be rotating and is at a temperature near the melting temperature of the workpiece. Flow fields are obtained from the study. The vector plot of the flow field shows that the flow is not evenly distributed over the cutter surface, as well as the uneven distribution of the lubricant in the direction of the cutter rotation. It can be seen that the cutting fluid has not completely penetrated the tool edges. The turbulence created by the cutter rotation in the proximity of the tool throws oil drops out of the cutting zone. The nozzle position in relation to the feed direction is very important in order to obtain the optimum effect of the MQL flow.
Directory of Open Access Journals (Sweden)
Bin Zhang
2017-01-01
Full Text Available To improve its working performance, the flow ripple characteristics of an axial piston pump were investigated with software which uses computational fluid dynamics (CFD technology. The simulation accuracy was significantly optimized through the use of the improved compressible fluid model. Flow conditions of the pump were tested using a pump flow ripple test rig, and the simulation results of the CFD model showed good agreement with the experimental data. Additionally, the composition of the flow ripple was analyzed using the improved CFD model, and the results showed that the compression ripple makes up 88% of the flow ripple. The flow dynamics of the piston pump is mainly caused by the pressure difference between the intake and discharge ports of the valve plates and the fluid oil compressibility.
HPCToolkit: performance tools for scientific computing
Energy Technology Data Exchange (ETDEWEB)
Tallent, N; Mellor-Crummey, J; Adhianto, L; Fagan, M; Krentel, M [Department of Computer Science, Rice University, Houston, TX 77005 (United States)
2008-07-15
As part of the U.S. Department of Energy's Scientific Discovery through Advanced Computing (SciDAC) program, science teams are tackling problems that require simulation and modeling on petascale computers. As part of activities associated with the SciDAC Center for Scalable Application Development Software (CScADS) and the Performance Engineering Research Institute (PERI), Rice University is building software tools for performance analysis of scientific applications on the leadership-class platforms. In this poster abstract, we briefly describe the HPCToolkit performance tools and how they can be used to pinpoint bottlenecks in SPMD and multi-threaded parallel codes. We demonstrate HPCToolkit's utility by applying it to two SciDAC applications: the S3D code for simulation of turbulent combustion and the MFDn code for ab initio calculations of microscopic structure of nuclei.
HPCToolkit: performance tools for scientific computing
International Nuclear Information System (INIS)
Tallent, N; Mellor-Crummey, J; Adhianto, L; Fagan, M; Krentel, M
2008-01-01
As part of the U.S. Department of Energy's Scientific Discovery through Advanced Computing (SciDAC) program, science teams are tackling problems that require simulation and modeling on petascale computers. As part of activities associated with the SciDAC Center for Scalable Application Development Software (CScADS) and the Performance Engineering Research Institute (PERI), Rice University is building software tools for performance analysis of scientific applications on the leadership-class platforms. In this poster abstract, we briefly describe the HPCToolkit performance tools and how they can be used to pinpoint bottlenecks in SPMD and multi-threaded parallel codes. We demonstrate HPCToolkit's utility by applying it to two SciDAC applications: the S3D code for simulation of turbulent combustion and the MFDn code for ab initio calculations of microscopic structure of nuclei
Fluid/Structure Interaction Studies of Aircraft Using High Fidelity Equations on Parallel Computers
Guruswamy, Guru; VanDalsem, William (Technical Monitor)
1994-01-01
Abstract Aeroelasticity which involves strong coupling of fluids, structures and controls is an important element in designing an aircraft. Computational aeroelasticity using low fidelity methods such as the linear aerodynamic flow equations coupled with the modal structural equations are well advanced. Though these low fidelity approaches are computationally less intensive, they are not adequate for the analysis of modern aircraft such as High Speed Civil Transport (HSCT) and Advanced Subsonic Transport (AST) which can experience complex flow/structure interactions. HSCT can experience vortex induced aeroelastic oscillations whereas AST can experience transonic buffet associated structural oscillations. Both aircraft may experience a dip in the flutter speed at the transonic regime. For accurate aeroelastic computations at these complex fluid/structure interaction situations, high fidelity equations such as the Navier-Stokes for fluids and the finite-elements for structures are needed. Computations using these high fidelity equations require large computational resources both in memory and speed. Current conventional super computers have reached their limitations both in memory and speed. As a result, parallel computers have evolved to overcome the limitations of conventional computers. This paper will address the transition that is taking place in computational aeroelasticity from conventional computers to parallel computers. The paper will address special techniques needed to take advantage of the architecture of new parallel computers. Results will be illustrated from computations made on iPSC/860 and IBM SP2 computer by using ENSAERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations.
Analytical performance modeling for computer systems
Tay, Y C
2013-01-01
This book is an introduction to analytical performance modeling for computer systems, i.e., writing equations to describe their performance behavior. It is accessible to readers who have taken college-level courses in calculus and probability, networking and operating systems. This is not a training manual for becoming an expert performance analyst. Rather, the objective is to help the reader construct simple models for analyzing and understanding the systems that they are interested in.Describing a complicated system abstractly with mathematical equations requires a careful choice of assumpti
Computer performance optimization systems, applications, processes
Osterhage, Wolfgang W
2013-01-01
Computing power performance was important at times when hardware was still expensive, because hardware had to be put to the best use. Later on this criterion was no longer critical, since hardware had become inexpensive. Meanwhile, however, people have realized that performance again plays a significant role, because of the major drain on system resources involved in developing complex applications. This book distinguishes between three levels of performance optimization: the system level, application level and business processes level. On each, optimizations can be achieved and cost-cutting p
Kröner, Dietmar; Resch, Michael
2016-01-01
This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS) in 2015. The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance. The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and engineers. The book comes with a wealth of color illustrations and tables of results.
Kröner, Dietmar; Resch, Michael; HLRS 2017
2018-01-01
This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS) in 2017. The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance.The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and engineers. The book comes with a wealth of color illustrations and tables of results.
SINDA/SINFLO computer routine, volume 1, revision A. [for fluid flow system analysis
Oren, J. A.; Williams, D. R.
1975-01-01
The SINFLO package was developed to modify the SINDA preprocessor to accept and store the input data for fluid flow systems analysis and adding the FLOSOL user subroutine to perform the flow solution. This reduced and simplified the user input required for analysis of flow problems. A temperature calculation method, the flow-hybrid method which was developed in previous VSD thermal simulator routines, was incorporated for calculating fluid temperatures. The calculation method accuracy was improved by using fluid enthalpy rather than specific heat for the convective term of the fluid temperature equation. Subroutines and data input requirements are described along with user subroutines, flow data storage, and usage of the plot program.
Aerodynamic research of a racing car based on wind tunnel test and computational fluid dynamics
Directory of Open Access Journals (Sweden)
Wang Jianfeng
2018-01-01
Full Text Available Wind tunnel test and computational fluid dynamics (CFD simulation are two main methods for the study of automotive aerodynamics. CFD simulation software solves the results in calculation by using the basic theory of aerodynamic. Calculation will inevitably lead to bias, and the wind tunnel test can effectively simulate the real driving condition, which is the most effective aerodynamics research method. This paper researches the aerodynamic characteristics of the wing of a racing car. Aerodynamic model of a racing car is established. Wind tunnel test is carried out and compared with the simulation results of computational fluid dynamics. The deviation of the two methods is small, and the accuracy of computational fluid dynamics simulation is verified. By means of CFD software simulation, the coefficients of six aerodynamic forces are fitted and the aerodynamic equations are obtained. Finally, the aerodynamic forces and torques of the racing car travel in bend are calculated.
Ramamurti, Ravi; Sandberg, William C; Löhner, Rainald; Walker, Jeffrey A; Westneat, Mark W
2002-10-01
Many fishes that swim with the paired pectoral fins use fin-stroke parameters that produce thrust force from lift in a mechanism of underwater flight. These locomotor mechanisms are of interest to behavioral biologists, biomechanics researchers and engineers. In the present study, we performed the first three-dimensional unsteady computations of fish swimming with oscillating and deforming fins. The objective of these computations was to investigate the fluid dynamics of force production associated with the flapping aquatic flight of the bird wrasse Gomphosus varius. For this computational work, we used the geometry of the wrasse and its pectoral fin, and previously measured fin kinematics, as the starting points for computational investigation of three-dimensional (3-D) unsteady fluid dynamics. We performed a 3-D steady computation and a complete set of 3-D quasisteady computations for a range of pectoral fin positions and surface velocities. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive remeshing was then used to compute the unsteady flow about the wrasse through several complete cycles of pectoral fin oscillation. The shape deformation of the pectoral fin throughout the oscillation was taken from the experimental kinematics. The pressure distribution on the body of the bird wrasse and its pectoral fins was computed and integrated to give body and fin forces which were decomposed into lift and thrust. The velocity field variation on the surface of the wrasse body, on the pectoral fins and in the near-wake was computed throughout the swimming cycle. We compared our computational results for the steady, quasi-steady and unsteady cases with the experimental data on axial and vertical acceleration obtained from the pectoral fin kinematics experiments. These comparisons show that steady state computations are incapable of describing the fluid dynamics of flapping fins. Quasi-steady state computations, with correct incorporation of
Directory of Open Access Journals (Sweden)
Fotev Vasko G.
2017-01-01
Full Text Available This article presents innovative method for increasing the speed of procedure which includes complex computational fluid dynamic calculations for finding the distance between flame openings of atmospheric gas burner that lead to minimal NO pollution. The method is based on standard features included in commercial computational fluid dynamic software and shortens computer working time roughly seven times in this particular case.
Status of computational fluid dynamics in the United States
International Nuclear Information System (INIS)
Kutler, P.; Steger, J.L.; Bailey, F.R.
1987-01-01
CFD-related progress in U.S. aerospace industries and research institutions is evaluated with respect to methods employed, their applications, and the computer technologies employed in their implementation. Goals for subsonic CFD are primarily aimed at greater fuel efficiency; those of supersonic CFD involve the achievement of high sustained cruise efficiency. Transatmospheric/hypersonic vehicles are noted to have recently become important concerns for CFD efforts. Attention is given to aspects of discretization, Euler and Navier-Stokes general purpose codes, zonal equation methods, internal and external flows, and the impact of supercomputers and their networks in advancing the state-of-the-art. 91 references
Computational Fluid Dynamics of Choanoﬂagellate Filter-Feeding
DEFF Research Database (Denmark)
Asadzadeh, Seyed Saeed; Walther, Jens Honore; Nielsen, Lasse Tor
Choanoﬂagellates are unicellular aquatic organisms with a single ﬂagellum that drives a feeding current through a funnel-shaped collar ﬁlter on which bacteria-sized prey are caught. Using computational ﬂuid dynamics (CFD) we model the beating ﬂagellum and the complex ﬁlter ﬂow of the choanoﬂagell...... to suggest a radically diﬀerent ﬁltration mechanism that requires a ﬂagellar vane (sheet), and addition of a wide vane in our CFD model allows us to correctly predict the observed clearance rate....
Directory of Open Access Journals (Sweden)
Sarim Ahmed
2018-06-01
Full Text Available A venturi scrubber is an important element of Filtered Containment Venting System (FCVS for the removal of aerosols in contaminated air. The present work involves computational fluid dynamics (CFD study of dust particle removal efficiency of a venturi scrubber operating in self-priming mode using ANSYS CFX. Titanium oxide (TiO2 particles having sizes of 1 micron have been taken as dust particles. CFD methodology to simulate the venturi scrubber has been first developed. The cascade atomization and breakup (CAB model has been used to predict deformation of water droplets, whereas the Eulerian–Lagrangian approach has been used to handle multiphase flow involving air, dust, and water. The developed methodology has been applied to simulate venturi scrubber geometry taken from the literature. Dust particle removal efficiency has been calculated for forced feed operation of venturi scrubber and found to be in good agreement with the results available in the literature. In the second part, venturi scrubber along with a tank has been modeled in CFX, and transient simulations have been performed to study self-priming phenomenon. Self-priming has been observed by plotting the velocity vector fields of water. Suction of water in the venturi scrubber occurred due to the difference between static pressure in the venturi scrubber and the hydrostatic pressure of water inside the tank. Dust particle removal efficiency has been calculated for inlet air velocities of 1 m/s and 3 m/s. It has been observed that removal efficiency is higher in case of higher inlet air velocity. Keywords: Computational Fluid Dynamics, Dust Particles, Filtered Containment Venting System, Self-priming Venturi Scrubber, Venturi Scrubber
Lee, Hyung B.; Ghia, Urmila; Bayyuk, Sami; Oberkampf, William L.; Roy, Christopher J.; Benek, John A.; Rumsey, Christopher L.; Powers, Joseph M.; Bush, Robert H.; Mani, Mortaza
2016-01-01
Computational fluid dynamics (CFD) and other advanced modeling and simulation (M&S) methods are increasingly relied on for predictive performance, reliability and safety of engineering systems. Analysts, designers, decision makers, and project managers, who must depend on simulation, need practical techniques and methods for assessing simulation credibility. The AIAA Guide for Verification and Validation of Computational Fluid Dynamics Simulations (AIAA G-077-1998 (2002)), originally published in 1998, was the first engineering standards document available to the engineering community for verification and validation (V&V) of simulations. Much progress has been made in these areas since 1998. The AIAA Committee on Standards for CFD is currently updating this Guide to incorporate in it the important developments that have taken place in V&V concepts, methods, and practices, particularly with regard to the broader context of predictive capability and uncertainty quantification (UQ) methods and approaches. This paper will provide an overview of the changes and extensions currently underway to update the AIAA Guide. Specifically, a framework for predictive capability will be described for incorporating a wide range of error and uncertainty sources identified during the modeling, verification, and validation processes, with the goal of estimating the total prediction uncertainty of the simulation. The Guide's goal is to provide a foundation for understanding and addressing major issues and concepts in predictive CFD. However, this Guide will not recommend specific approaches in these areas as the field is rapidly evolving. It is hoped that the guidelines provided in this paper, and explained in more detail in the Guide, will aid in the research, development, and use of CFD in engineering decision-making.
A methodology for performing computer security reviews
International Nuclear Information System (INIS)
Hunteman, W.J.
1991-01-01
DOE Order 5637.1, ''Classified Computer Security,'' requires regular reviews of the computer security activities for an ADP system and for a site. Based on experiences gained in the Los Alamos computer security program through interactions with DOE facilities, we have developed a methodology to aid a site or security officer in performing a comprehensive computer security review. The methodology is designed to aid a reviewer in defining goals of the review (e.g., preparation for inspection), determining security requirements based on DOE policies, determining threats/vulnerabilities based on DOE and local threat guidance, and identifying critical system components to be reviewed. Application of the methodology will result in review procedures and checklists oriented to the review goals, the target system, and DOE policy requirements. The review methodology can be used to prepare for an audit or inspection and as a periodic self-check tool to determine the status of the computer security program for a site or specific ADP system. 1 tab
A methodology for performing computer security reviews
International Nuclear Information System (INIS)
Hunteman, W.J.
1991-01-01
This paper reports on DIE Order 5637.1, Classified Computer Security, which requires regular reviews of the computer security activities for an ADP system and for a site. Based on experiences gained in the Los Alamos computer security program through interactions with DOE facilities, the authors have developed a methodology to aid a site or security officer in performing a comprehensive computer security review. The methodology is designed to aid a reviewer in defining goals of the review (e.g., preparation for inspection), determining security requirements based on DOE policies, determining threats/vulnerabilities based on DOE and local threat guidance, and identifying critical system components to be reviewed. Application of the methodology will result in review procedures and checklists oriented to the review goals, the target system, and DOE policy requirements. The review methodology can be used to prepare for an audit or inspection and as a periodic self-check tool to determine the status of the computer security program for a site or specific ADP system
Computational multiscale modeling of fluids and solids theory and applications
Steinhauser, Martin Oliver
2017-01-01
The idea of the book is to provide a comprehensive overview of computational physics methods and techniques, that are used for materials modeling on different length and time scales. Each chapter first provides an overview of the basic physical principles which are the basis for the numerical and mathematical modeling on the respective length-scale. The book includes the micro-scale, the meso-scale and the macro-scale, and the chapters follow this classification. The book explains in detail many tricks of the trade of some of the most important methods and techniques that are used to simulate materials on the perspective levels of spatial and temporal resolution. Case studies are included to further illustrate some methods or theoretical considerations. Example applications for all techniques are provided, some of which are from the author’s own contributions to some of the research areas. The second edition has been expanded by new sections in computational models on meso/macroscopic scales for ocean and a...
HIGH PERFORMANCE PHOTOGRAMMETRIC PROCESSING ON COMPUTER CLUSTERS
Directory of Open Access Journals (Sweden)
V. N. Adrov
2012-07-01
Full Text Available Most cpu consuming tasks in photogrammetric processing can be done in parallel. The algorithms take independent bits as input and produce independent bits as output. The independence of bits comes from the nature of such algorithms since images, stereopairs or small image blocks parts can be processed independently. Many photogrammetric algorithms are fully automatic and do not require human interference. Photogrammetric workstations can perform tie points measurements, DTM calculations, orthophoto construction, mosaicing and many other service operations in parallel using distributed calculations. Distributed calculations save time reducing several days calculations to several hours calculations. Modern trends in computer technology show the increase of cpu cores in workstations, speed increase in local networks, and as a result dropping the price of the supercomputers or computer clusters that can contain hundreds or even thousands of computing nodes. Common distributed processing in DPW is usually targeted for interactive work with a limited number of cpu cores and is not optimized for centralized administration. The bottleneck of common distributed computing in photogrammetry can be in the limited lan throughput and storage performance, since the processing of huge amounts of large raster images is needed.
Monitoring SLAC High Performance UNIX Computing Systems
International Nuclear Information System (INIS)
Lettsome, Annette K.
2005-01-01
Knowledge of the effectiveness and efficiency of computers is important when working with high performance systems. The monitoring of such systems is advantageous in order to foresee possible misfortunes or system failures. Ganglia is a software system designed for high performance computing systems to retrieve specific monitoring information. An alternative storage facility for Ganglia's collected data is needed since its default storage system, the round-robin database (RRD), struggles with data integrity. The creation of a script-driven MySQL database solves this dilemma. This paper describes the process took in the creation and implementation of the MySQL database for use by Ganglia. Comparisons between data storage by both databases are made using gnuplot and Ganglia's real-time graphical user interface
Thermal Performance of a Cryogenic Fluid Management Cubesat Mission
Berg, J. J.; Oliveira, J. M.; Congiardo, J. F.; Walls, L. K.; Putman, P. T.; Haberbusch, M. S.
2013-01-01
Development for an in-space demonstration of a CubeS at as a Cryogenic Fluid Management (CFM) test bed is currently underway. The favorable economics of CubeSats make them appealing for technology development activity. While their size limits testing to smaller scales, many of the regimes relevant to CFM can still be achieved. The first demo flight of this concept, CryoCube®-1, will focus on oxygen liquefaction and low-gravity level sensing using Reduced Gravity CryoTracker®. An extensive thermal modeling effort has been underway to both demonstrate concept feasibility and drive the prototype design. The satellite will utilize both a sun- and earth-shield to passively cool its experimental tank below 115 K. An on-board gas generator will create high pressure gaseous oxygen, which will be throttled into a bottle in the experimental node and condensed. The resulting liquid will be used to perform various experiments related to level sensing. Modeling efforts have focused on the spacecraft thermal performance and its effects on condensation in the experimental node. Parametric analyses for both optimal and suboptimal conditions have been considered and are presented herein.
International Nuclear Information System (INIS)
Fiantini, Rosalina; Umar, Efrizon
2010-01-01
Common energy crisis has modified the national energy policy which is in the beginning based on natural resources becoming based on technology, therefore the capability to understanding the basic and applied science is needed to supporting those policies. National energy policy which aims at new energy exploitation, such as nuclear energy is including many efforts to increase the safety reactor core condition and optimize the related aspects and the ability to build new research reactor with properly design. The previous analysis of the modification TRIGA 2000 Reactor design indicates that forced convection of the primary coolant system put on an effect to the flow characteristic in the reactor core, but relatively insignificant effect to the flow velocity in the reactor core. In this analysis, the lid of reactor core is closed. However the forced convection effect is still presented. This analysis shows the fluid flow velocity vector in the model area without exception. Result of this analysis indicates that in the original design of TRIGA 2000 reactor, there is still forced convection effects occur but less than in the modified TRIGA 2000 design.
Cloud Computing for Maintenance Performance Improvement
Kour, Ravdeep; Karim, Ramin; Parida, Aditya
2013-01-01
Cloud Computing is an emerging research area. It can be utilised for acquiring an effective and efficient information logistics. This paper uses cloud-based technology for the establishment of information logistics for railway system which requires information based on data from different data sources (e.g. railway maintenance, railway operation, and railway business data). In order to improve the performance of the maintenance process relevant data from various sources need to be acquired, f...
High Performance Computing Operations Review Report
Energy Technology Data Exchange (ETDEWEB)
Cupps, Kimberly C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2013-12-19
The High Performance Computing Operations Review (HPCOR) meeting—requested by the ASC and ASCR program headquarters at DOE—was held November 5 and 6, 2013, at the Marriott Hotel in San Francisco, CA. The purpose of the review was to discuss the processes and practices for HPC integration and its related software and facilities. Experiences and lessons learned from the most recent systems deployed were covered in order to benefit the deployment of new systems.
Techniques for grid manipulation and adaptation. [computational fluid dynamics
Choo, Yung K.; Eisemann, Peter R.; Lee, Ki D.
1992-01-01
Two approaches have been taken to provide systematic grid manipulation for improved grid quality. One is the control point form (CPF) of algebraic grid generation. It provides explicit control of the physical grid shape and grid spacing through the movement of the control points. It works well in the interactive computer graphics environment and hence can be a good candidate for integration with other emerging technologies. The other approach is grid adaptation using a numerical mapping between the physical space and a parametric space. Grid adaptation is achieved by modifying the mapping functions through the effects of grid control sources. The adaptation process can be repeated in a cyclic manner if satisfactory results are not achieved after a single application.
Error Estimation and Uncertainty Propagation in Computational Fluid Mechanics
Zhu, J. Z.; He, Guowei; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
Numerical simulation has now become an integral part of engineering design process. Critical design decisions are routinely made based on the simulation results and conclusions. Verification and validation of the reliability of the numerical simulation is therefore vitally important in the engineering design processes. We propose to develop theories and methodologies that can automatically provide quantitative information about the reliability of the numerical simulation by estimating numerical approximation error, computational model induced errors and the uncertainties contained in the mathematical models so that the reliability of the numerical simulation can be verified and validated. We also propose to develop and implement methodologies and techniques that can control the error and uncertainty during the numerical simulation so that the reliability of the numerical simulation can be improved.
Advances in engineering turbulence modeling. [computational fluid dynamics
Shih, T.-H.
1992-01-01
Some new developments in two equation models and second order closure models are presented. In this paper, modified two equation models are proposed to remove shortcomings such as computing flows over complex geometries and the ad hoc treatment near the separation and reattachment points. The calculations using various two equation models are compared with direct numerical solutions of channel flows and flat plate boundary layers. Development of second order closure models will also be discussed with emphasis on the modeling of pressure related correlation terms and dissipation rates in the second moment equations. All existing models poorly predict the normal stresses near the wall and fail to predict the three dimensional effect of mean flow on the turbulence. The newly developed second order near-wall turbulence model to be described in this paper is capable of capturing the near-wall behavior of turbulence as well as the effect of three dimension mean flow on the turbulence.
Computational fluid dynamics (CFD) study on the fetal aortic coarctation
Zhou, Yue; Zhang, Yutao; Wang, Jingying
2018-03-01
Blood flows in normal and coarctate fetal aortas are simulated by the CFD technique using T-rex grids. The three-dimensional (3-D) digital model of the fetal arota is reconstructed by the computer-aided design (CAD) software based on two-dimensional (2-D) ultrasono tomographic images. Simulation results displays the development and enhancement of the secondary flow structure in the coarctate fetal arota. As the diameter narrow ratio rises greater than 45%, the pressure and wall shear stress (WSS) of the aorta arch increase exponentially, which is consistent with the conventional clinical concept. The present study also demonstrates that CFD is a very promising assistant technique to investigate human cardiovascular diseases.
Methodology for coupling computational fluid dynamics and integral transport neutronics
International Nuclear Information System (INIS)
Thomas, J. W.; Zhong, Z.; Sofu, T.; Downar, T. J.
2004-01-01
The CFD code STAR-CD was coupled to the integral transport code DeCART in order to provide high-fidelity, full physics reactor simulations. An interface program was developed to perform the tasks of mapping the STAR-CD mesh to the DeCART mesh, managing all communication between STAR-CD and DeCART, and monitoring the convergence of the coupled calculations. The interface software was validated by comparing coupled calculation results with those obtained using an independently developed interface program. An investigation into the convergence characteristics of coupled calculations was performed using several test models on a multiprocessor LINUX cluster. The results indicate that the optimal convergence of the coupled field calculation depends on several factors, to include the tolerance of the STAR-CD solution and the number of DeCART transport sweeps performed before exchanging data between codes. Results for a 3D, multi-assembly PWR problem on 12 PEs of the LINUX cluster indicate the best performance is achieved when the STAR-CD tolerance and number of DeCART transport sweeps are chosen such that the two fields converge at approximately the same rate. (authors)
Mota, J.P.B.; Esteves, I.A.A.C.; Rostam-Abadi, M.
2004-01-01
A computational fluid dynamics (CFD) software package has been coupled with the dynamic process simulator of an adsorption storage tank for methane fuelled vehicles. The two solvers run as independent processes and handle non-overlapping portions of the computational domain. The codes exchange data on the boundary interface of the two domains to ensure continuity of the solution and of its gradient. A software interface was developed to dynamically suspend and activate each process as necessary, and be responsible for data exchange and process synchronization. This hybrid computational tool has been successfully employed to accurately simulate the discharge of a new tank design and evaluate its performance. The case study presented here shows that CFD and process simulation are highly complementary computational tools, and that there are clear benefits to be gained from a close integration of the two. ?? 2004 Elsevier Ltd. All rights reserved.
Computational Fluid Dynamics Uncertainty Analysis Applied to Heat Transfer over a Flat Plate
Groves, Curtis Edward; Ilie, Marcel; Schallhorn, Paul A.
2013-01-01
There have been few discussions on using Computational Fluid Dynamics (CFD) without experimental validation. Pairing experimental data, uncertainty analysis, and analytical predictions provides a comprehensive approach to verification and is the current state of the art. With pressed budgets, collecting experimental data is rare or non-existent. This paper investigates and proposes a method to perform CFD uncertainty analysis only from computational data. The method uses current CFD uncertainty techniques coupled with the Student-T distribution to predict the heat transfer coefficient over a at plate. The inputs to the CFD model are varied from a specified tolerance or bias error and the difference in the results are used to estimate the uncertainty. The variation in each input is ranked from least to greatest to determine the order of importance. The results are compared to heat transfer correlations and conclusions drawn about the feasibility of using CFD without experimental data. The results provide a tactic to analytically estimate the uncertainty in a CFD model when experimental data is unavailable
International Nuclear Information System (INIS)
Ghasemian, Masoud; Ashrafi, Z. Najafian; Sedaghat, Ahmad
2017-01-01
Highlights: • A review on CFD simulation technique for Darrieus wind turbines is provided. • Recommendations and guidelines toward reliable and accurate simulations are presented. • Different progresses in CFD simulation of Darrieus wind turbines are addressed. - Abstract: The global warming threats, the presence of policies on support of renewable energies, and the desire for clean smart cities are the major drives for most recent researches on developing small wind turbines in urban environments. VAWTs (vertical axis wind turbines) are most appealing for energy harvesting in the urban environment. This is attributed due to structural simplicity, wind direction independency, no yaw mechanism required, withstand high turbulence winds, cost effectiveness, easier maintenance, and lower noise emission of VAWTs. This paper reviews recent published works on CFD (computational fluid dynamic) simulations of Darrieus VAWTs. Recommendations and guidelines are presented for turbulence modeling, spatial and temporal discretization, numerical schemes and algorithms, and computational domain size. The operating and geometrical parameters such as tip speed ratio, wind speed, solidity, blade number and blade shapes are fully investigated. The purpose is to address different progresses in simulations areas such as blade profile modification and optimization, wind turbine performance augmentation using guide vanes, wind turbine wake interaction in wind farms, wind turbine aerodynamic noise reduction, dynamic stall control, self-starting characteristics, and effects of unsteady and skewed wind conditions.
Marinho, Daniel A; Barbosa, Tiago M; Rouboa, Abel I; Silva, António J
2011-09-01
Nowadays the underwater gliding after the starts and the turns plays a major role in the overall swimming performance. Hence, minimizing hydrodynamic drag during the underwater phases should be a main aim during swimming. Indeed, there are several postures that swimmers can assume during the underwater gliding, although experimental results were not conclusive concerning the best body position to accomplish this aim. Therefore, the purpose of this study was to analyse the effect in hydrodynamic drag forces of using different body positions during gliding through computational fluid dynamics (CFD) methodology. For this purpose, two-dimensional models of the human body in steady flow conditions were studied. Two-dimensional virtual models had been created: (i) a prone position with the arms extended at the front of the body; (ii) a prone position with the arms placed alongside the trunk; (iii) a lateral position with the arms extended at the front and; (iv) a dorsal position with the arms extended at the front. The drag forces were computed between speeds of 1.6 m/s and 2 m/s in a two-dimensional Fluent(®) analysis. The positions with the arms extended at the front presented lower drag values than the position with the arms aside the trunk. The lateral position was the one in which the drag was lower and seems to be the one that should be adopted during the gliding after starts and turns.
Vectorization on the star computer of several numerical methods for a fluid flow problem
Lambiotte, J. J., Jr.; Howser, L. M.
1974-01-01
A reexamination of some numerical methods is considered in light of the new class of computers which use vector streaming to achieve high computation rates. A study has been made of the effect on the relative efficiency of several numerical methods applied to a particular fluid flow problem when they are implemented on a vector computer. The method of Brailovskaya, the alternating direction implicit method, a fully implicit method, and a new method called partial implicitization have been applied to the problem of determining the steady state solution of the two-dimensional flow of a viscous imcompressible fluid in a square cavity driven by a sliding wall. Results are obtained for three mesh sizes and a comparison is made of the methods for serial computation.
Partitioned Fluid-Structure Interaction for Full Rotor Computations Using CFD
DEFF Research Database (Denmark)
Heinz, Joachim Christian
) based aerodynamic model which is computationally cheap but includes several limitations and corrections in order to account for three-dimensional and unsteady eects. The present work discusses the development of an aero-elastic simulation tool where high-fidelity computational fluid dynamics (CFD......) is used to model the aerodynamics of the flexible wind turbine rotor. Respective CFD computations are computationally expensive but do not show the limitations of the BEM-based models. It is one of the first times that high-fidelity fluid-structure interaction (FSI) simulations are used to model the aero......-elastic response of an entire wind turbine rotor. The work employs a partitioned FSI coupling between the multi-body-based structural model of the aero-elastic solver HAWC2 and the finite volume CFD solver EllipSys3D. In order to establish an FSI coupling of sufficient time accuracy and sufficient numerical...
Fast Virtual Fractional Flow Reserve Based Upon Steady-State Computational Fluid Dynamics Analysis
Directory of Open Access Journals (Sweden)
Paul D. Morris, PhD
2017-08-01
Full Text Available Fractional flow reserve (FFR-guided percutaneous intervention is superior to standard assessment but remains underused. The authors have developed a novel “pseudotransient” analysis protocol for computing virtual fractional flow reserve (vFFR based upon angiographic images and steady-state computational fluid dynamics. This protocol generates vFFR results in 189 s (cf >24 h for transient analysis using a desktop PC, with <1% error relative to that of full-transient computational fluid dynamics analysis. Sensitivity analysis demonstrated that physiological lesion significance was influenced less by coronary or lesion anatomy (33% and more by microvascular physiology (59%. If coronary microvascular resistance can be estimated, vFFR can be accurately computed in less time than it takes to make invasive measurements.
Directory of Open Access Journals (Sweden)
Pankaj K. Singh
2009-01-01
Full Text Available Objective. The importance of hemodynamics in the etiopathogenesis of intracranial aneurysms (IAs is widely accepted. Computational fluid dynamics (CFD is being used increasingly for hemodynamic predictions. However, alogn with the continuing development and validation of these tools, it is imperative to collect the opinion of the clinicians. Methods. A workshop on CFD was conducted during the European Society of Minimally Invasive Neurological Therapy (ESMINT Teaching Course, Lisbon, Portugal. 36 delegates, mostly clinicians, performed supervised CFD analysis for an IA, using the @neuFuse software developed within the European project @neurIST. Feedback on the workshop was collected and analyzed. The performance was assessed on a scale of 1 to 4 and, compared with experts' performance. Results. Current dilemmas in the management of unruptured IAs remained the most important motivating factor to attend the workshop and majority of participants showed interest in participating in a multicentric trial. The participants achieved an average score of 2.52 (range 0–4 which was 63% (range 0–100% of an expert user. Conclusions. Although participants showed a manifest interest in CFD, there was a clear lack of awareness concerning the role of hemodynamics in the etiopathogenesis of IAs and the use of CFD in this context. More efforts therefore are required to enhance understanding of the clinicians in the subject.
Energy Technology Data Exchange (ETDEWEB)
Mays, Brian [AREVA Federal Services, Lynchburg, VA (United States); Jackson, R. Brian [TerraPower, Bellevue, WA (United States)
2017-03-08
The project, Toward a Longer Life Core: Thermal Hydraulic CFD Simulations and Experimental Investigation of Deformed Fuel Assemblies, DOE Project code DE-NE0008321, was a verification and validation project for flow and heat transfer through wire wrapped simulated liquid metal fuel assemblies that included both experiments and computational fluid dynamics simulations of those experiments. This project was a two year collaboration between AREVA, TerraPower, Argonne National Laboratory and Texas A&M University. Experiments were performed by AREVA and Texas A&M University. Numerical simulations of these experiments were performed by TerraPower and Argonne National Lab. Project management was performed by AREVA Federal Services. The first of a kind project resulted in the production of both local point temperature measurements and local flow mixing experiment data paired with numerical simulation benchmarking of the experiments. The project experiments included the largest wire-wrapped pin assembly Mass Index of Refraction (MIR) experiment in the world, the first known wire-wrapped assembly experiment with deformed duct geometries and the largest numerical simulations ever produced for wire-wrapped bundles.
Computational fluid dynamic and thermal analysis of Lithium-ion battery pack with air cooling
International Nuclear Information System (INIS)
Saw, Lip Huat; Ye, Yonghuang; Tay, Andrew A.O.; Chong, Wen Tong; Kuan, Seng How; Yew, Ming Chian
2016-01-01
Highlights: • We designed and analyzed the thermal behavior of the Li-ion battery pack. • We analyzed the heat generation of 38,120 Li-ion cell using ARC. • We validated the simulation results with experimental studies. • We developed the correlations of Nu and Re for the air cooling battery pack. - Abstract: A battery pack is produced by connecting the cells in series and/or in parallel to provide the necessary power for electric vehicles (EVs). Those parameters affecting cost and reliability of the EVs, including cycle life, capacity, durability and warranty are highly dependent on the thermal management system. In this work, computational fluid dynamic analysis is performed to investigate the air cooling system for a 38,120 cell battery pack. The battery pack contained 24 pieces of 38,120 cells, copper bus bars, intake and exhaust plenum and holding plates with venting holes. Heat generated by the cell during charging is measured using an accelerating rate calorimeter. Thermal performances of the battery pack were analyzed with various mass flow rates of cooling air using steady state simulation. The correlation between Nu number and Re number were deduced from the numerical modeling results and compared with literature. Additionally, an experimental testing of the battery pack at different charging rates is conducted to validate the correlation. This method provides a simple way to estimate thermal performance of the battery pack when the battery pack is large and full transient simulation is not viable.
Parametric Analysis of a Hypersonic Inlet using Computational Fluid Dynamics
Oliden, Daniel
For CFD validation, hypersonic flow fields are simulated and compared with experimental data specifically designed to recreate conditions found by hypersonic vehicles. Simulated flow fields on a cone-ogive with flare at Mach 7.2 are compared with experimental data from NASA Ames Research Center 3.5" hypersonic wind tunnel. A parametric study of turbulence models is presented and concludes that the k-kl-omega transition and SST transition turbulence model have the best correlation. Downstream of the flare's shockwave, good correlation is found for all boundary layer profiles, with some slight discrepancies of the static temperature near the surface. Simulated flow fields on a blunt cone with flare above Mach 10 are compared with experimental data from CUBRC LENS hypervelocity shock tunnel. Lack of vibrational non-equilibrium calculations causes discrepancies in heat flux near the leading edge. Temperature profiles, where non-equilibrium effects are dominant, are compared with the dissociation of molecules to show the effects of dissociation on static temperature. Following the validation studies is a parametric analysis of a hypersonic inlet from Mach 6 to 20. Compressor performance is investigated for numerous cowl leading edge locations up to speeds of Mach 10. The variable cowl study showed positive trends in compressor performance parameters for a range of Mach numbers that arise from maximizing the intake of compressed flow. An interesting phenomenon due to the change in shock wave formation for different Mach numbers developed inside the cowl that had a negative influence on the total pressure recovery. Investigation of the hypersonic inlet at different altitudes is performed to study the effects of Reynolds number, and consequently, turbulent viscous effects on compressor performance. Turbulent boundary layer separation was noted as the cause for a change in compressor performance parameters due to a change in Reynolds number. This effect would not be
Transepithelial Na+ transport and the intracellular fluids: a computer study.
Civan, M M; Bookman, R J
1982-01-01
Computer simulations of tight epithelia under three experimental conditions have been carried out, using the rheogenic nonlinear model of Lew, Ferreira and Moura (Proc. Roy. Soc. London. B 206:53-83, 1979) based largely on the formulation of Koefoed-Johnsen and Ussing (Acta Physiol. Scand. 42: 298-308. 1958). First, analysis of the transition between the short-circuited and open-circuited states has indicated that (i) apical Cl- permeability is a critical parameter requiring experimental definition in order to analyze cell volume regulation, and (ii) contrary to certain experimental reports, intracellular Na+ concentration (ccNa) is expected to be a strong function of transepithelial clamping voltage. Second, analysis of the effects of lowering serosal K+ concentration (csK) indicates that the basic model cannot simulate several well-documented observations; these defects can be overcome, at least qualitatively, by modifying the model to take account of the negative feedback interaction likely to exist between the apical Na+ permeability and ccNa. Third, analysis of the strongly supports the concept that osmotically induced permeability changes in the apical intercellular junctions play a physiological role in conserving the body's stores of NaCl. The analyses also demonstrate that the importance of Na+ entry across the basolateral membrane is strongly dependent upon transepithelial potential, cmNa and csK; under certain conditions, net Na+ entry could be appreciably greater across the basolateral than across the apical membrane.
International Nuclear Information System (INIS)
Zhang, Shuai; Morita, Koji; Shirakawa, Noriyuki; Yamamoto, Yuichi
2010-01-01
The COMPASS code is designed based on the moving particle semi-implicit method to simulate various complex mesoscale phenomena relevant to core disruptive accidents of sodium-cooled fast reactors. In this study, a computational framework for fluid-solid mixture flow simulations was developed for the COMPASS code. The passively moving solid model was used to simulate hydrodynamic interactions between fluid and solids. Mechanical interactions between solids were modeled by the distinct element method. A multi-time-step algorithm was introduced to couple these two calculations. The proposed computational framework for fluid-solid mixture flow simulations was verified by the comparison between experimental and numerical studies on the water-dam break with multiple solid rods. (author)
Computational electrochemo-fluid dynamics modeling in a uranium electrowinning cell
International Nuclear Information System (INIS)
Kim, K.R.; Choi, S.Y.; Kim, S.H.; Shim, J.B.; Paek, S.; Kim, I.T.
2014-01-01
A computational electrochemo-fluid dynamics model has been developed to describe the electrowinning behavior in an electrolyte stream through a planar electrode cell system. Electrode reaction of the uranium electrowinning process from a molten-salt electrolyte stream was modeled to illustrate the details of the flow-assisted mass transport of ions to the cathode. This modeling approach makes it possible to represent variations of the convective diffusion limited current density by taking into account the concentration profile at the electrode surface as a function of the flow characteristics and applied current density in a commercially available computational fluid dynamics platform. It was possible to predict the conventional current-voltage relation in addition to details of electrolyte fluid dynamics and electrochemical variables, such as the flow field, species concentrations, potential, and current distributions throughout the galvanostatic electrolysis cell. (author)
The path toward HEP High Performance Computing
International Nuclear Information System (INIS)
Apostolakis, John; Brun, René; Gheata, Andrei; Wenzel, Sandro; Carminati, Federico
2014-01-01
High Energy Physics code has been known for making poor use of high performance computing architectures. Efforts in optimising HEP code on vector and RISC architectures have yield limited results and recent studies have shown that, on modern architectures, it achieves a performance between 10% and 50% of the peak one. Although several successful attempts have been made to port selected codes on GPUs, no major HEP code suite has a 'High Performance' implementation. With LHC undergoing a major upgrade and a number of challenging experiments on the drawing board, HEP cannot any longer neglect the less-than-optimal performance of its code and it has to try making the best usage of the hardware. This activity is one of the foci of the SFT group at CERN, which hosts, among others, the Root and Geant4 project. The activity of the experiments is shared and coordinated via a Concurrency Forum, where the experience in optimising HEP code is presented and discussed. Another activity is the Geant-V project, centred on the development of a highperformance prototype for particle transport. Achieving a good concurrency level on the emerging parallel architectures without a complete redesign of the framework can only be done by parallelizing at event level, or with a much larger effort at track level. Apart the shareable data structures, this typically implies a multiplication factor in terms of memory consumption compared to the single threaded version, together with sub-optimal handling of event processing tails. Besides this, the low level instruction pipelining of modern processors cannot be used efficiently to speedup the program. We have implemented a framework that allows scheduling vectors of particles to an arbitrary number of computing resources in a fine grain parallel approach. The talk will review the current optimisation activities within the SFT group with a particular emphasis on the development perspectives towards a simulation framework able to profit
Particle Image Velocimetry and Computational Fluid Dynamics Analysis of Fuel Cell Manifold
DEFF Research Database (Denmark)
Lebæk, Jesper; Blazniak Andreasen, Marcin; Andresen, Henrik Assenholm
2010-01-01
The inlet effect on the manifold flow in a fuel cell stack was investigated by means of numerical methods (computational fluid dynamics) and experimental methods (particle image velocimetry). At a simulated high current density situation the flow field was mapped on a 70 cell simulated cathode...
An Innovative Improvement of Engineering Learning System Using Computational Fluid Dynamics Concept
Hung, T. C.; Wang, S. K.; Tai, S. W.; Hung, C. T.
2007-01-01
An innovative concept of an electronic learning system has been established in an attempt to achieve a technology that provides engineering students with an instructive and affordable framework for learning engineering-related courses. This system utilizes an existing Computational Fluid Dynamics (CFD) package, Active Server Pages programming,…
Computer simulation studies in fluid and calcium regulation and orthostatic intolerance
1985-01-01
The systems analysis approach to physiological research uses mathematical models and computer simulation. Major areas of concern during prolonged space flight discussed include fluid and blood volume regulation; cardiovascular response during shuttle reentry; countermeasures for orthostatic intolerance; and calcium regulation and bone atrophy. Potential contributions of physiologic math models to future flight experiments are examined.
Directory of Open Access Journals (Sweden)
Alina Żogała
2014-01-01
Originality/value: This paper presents state of art in the field of coal gasification modeling using kinetic and computational fluid dynamics approach. The paper also presents own comparative analysis (concerned with mathematical formulation, input data and parameters, basic assumptions, obtained results etc. of the most important models of underground coal gasification.
A computational fluid dynamics model for designing heat exchangers based on natural convection
Dirkse, M.H.; Loon, van W.K.P.; Walle, van der T.; Speetjens, S.L.; Bot, G.P.A.
2006-01-01
A computational fluid dynamics model was created for the design of a natural convection shell-and-tube heat exchanger with baffles. The flow regime proved to be turbulent and this was modelled using the k¿¿ turbulence model. The features of the complex geometry were simplified considerably resulting
Research Summary 3-D Computational Fluid Dynamics (CFD) Model Of The Human Respiratory System
The U.S. EPA’s Office of Research and Development (ORD) has developed a 3-D computational fluid dynamics (CFD) model of the human respiratory system that allows for the simulation of particulate based contaminant deposition and clearance, while being adaptable for age, ethnicity,...
Computational fluid dynamics simulations of blood flow regularized by 3D phase contrast MRI
DEFF Research Database (Denmark)
Rispoli, Vinicius C; Nielsen, Jon; Nayak, Krishna S
2015-01-01
BACKGROUND: Phase contrast magnetic resonance imaging (PC-MRI) is used clinically for quantitative assessment of cardiovascular flow and function, as it is capable of providing directly-measured 3D velocity maps. Alternatively, vascular flow can be estimated from model-based computation fluid dyn...
Computational Fluid Dynamics for nuclear applications: from CFD to multi-scale CMFD
Energy Technology Data Exchange (ETDEWEB)
Yadigaroglu, G. [Swiss Federal Institute of Technology-Zurich (ETHZ), Nuclear Engineering Laboratory, ETH-Zentrum, CLT CH-8092 Zurich (Switzerland)]. E-mail: yadi@ethz.ch
2005-02-01
New trends in computational methods for nuclear reactor thermal-hydraulics are discussed; traditionally, these have been based on the two-fluid model. Although CFD computations for single phase flows are commonplace, Computational Multi-Fluid Dynamics (CMFD) is still under development. One-fluid methods coupled with interface tracking techniques provide interesting opportunities and enlarge the scope of problems that can be solved. For certain problems, one may have to conduct 'cascades' of computations at increasingly finer scales to resolve all issues. The case study of condensation of steam/air mixtures injected from a downward-facing vent into a pool of water and a proposed CMFD initiative to numerically model Critical Heat Flux (CHF) illustrate such cascades. For the venting problem, a variety of tools are used: a system code for system behaviour; an interface-tracking method (Volume of Fluid, VOF) to examine the behaviour of large bubbles; direct-contact condensation can be treated either by Direct Numerical Simulation (DNS) or by analytical methods.
Computational Fluid Dynamics for nuclear applications: from CFD to multi-scale CMFD
International Nuclear Information System (INIS)
Yadigaroglu, G.
2005-01-01
New trends in computational methods for nuclear reactor thermal-hydraulics are discussed; traditionally, these have been based on the two-fluid model. Although CFD computations for single phase flows are commonplace, Computational Multi-Fluid Dynamics (CMFD) is still under development. One-fluid methods coupled with interface tracking techniques provide interesting opportunities and enlarge the scope of problems that can be solved. For certain problems, one may have to conduct 'cascades' of computations at increasingly finer scales to resolve all issues. The case study of condensation of steam/air mixtures injected from a downward-facing vent into a pool of water and a proposed CMFD initiative to numerically model Critical Heat Flux (CHF) illustrate such cascades. For the venting problem, a variety of tools are used: a system code for system behaviour; an interface-tracking method (Volume of Fluid, VOF) to examine the behaviour of large bubbles; direct-contact condensation can be treated either by Direct Numerical Simulation (DNS) or by analytical methods
Benson, Thomas J.
1988-01-01
Supersonic external compression inlets are introduced, and the computational fluid dynamics (CFD) codes and tests needed to study flow associated with these inlets are outlined. Normal shock wave turbulent boundary layer interaction is discussed. Boundary layer control is considered. Glancing sidewall shock interaction is treated. The CFD validation of hypersonic inlet configurations is explained. Scramjet inlet modules are shown.
Ziebarth, John P.; Meyer, Doug
1992-01-01
The coordination is examined of necessary resources, facilities, and special personnel to provide technical integration activities in the area of computational fluid dynamics applied to propulsion technology. Involved is the coordination of CFD activities between government, industry, and universities. Current geometry modeling, grid generation, and graphical methods are established to use in the analysis of CFD design methodologies.
Mesh and Time-Step Independent Computational Fluid Dynamics (CFD) Solutions
Nijdam, Justin J.
2013-01-01
A homework assignment is outlined in which students learn Computational Fluid Dynamics (CFD) concepts of discretization, numerical stability and accuracy, and verification in a hands-on manner by solving physically realistic problems of practical interest to engineers. The students solve a transient-diffusion problem numerically using the common…
Computational Fluid Dynamics model of stratified atmospheric boundary-layer flow
DEFF Research Database (Denmark)
Koblitz, Tilman; Bechmann, Andreas; Sogachev, Andrey
2015-01-01
For wind resource assessment, the wind industry is increasingly relying on computational fluid dynamics models of the neutrally stratified surface-layer. So far, physical processes that are important to the whole atmospheric boundary-layer, such as the Coriolis effect, buoyancy forces and heat...
A High Performance VLSI Computer Architecture For Computer Graphics
Chin, Chi-Yuan; Lin, Wen-Tai
1988-10-01
A VLSI computer architecture, consisting of multiple processors, is presented in this paper to satisfy the modern computer graphics demands, e.g. high resolution, realistic animation, real-time display etc.. All processors share a global memory which are partitioned into multiple banks. Through a crossbar network, data from one memory bank can be broadcasted to many processors. Processors are physically interconnected through a hyper-crossbar network (a crossbar-like network). By programming the network, the topology of communication links among processors can be reconfigurated to satisfy specific dataflows of different applications. Each processor consists of a controller, arithmetic operators, local memory, a local crossbar network, and I/O ports to communicate with other processors, memory banks, and a system controller. Operations in each processor are characterized into two modes, i.e. object domain and space domain, to fully utilize the data-independency characteristics of graphics processing. Special graphics features such as 3D-to-2D conversion, shadow generation, texturing, and reflection, can be easily handled. With the current high density interconnection (MI) technology, it is feasible to implement a 64-processor system to achieve 2.5 billion operations per second, a performance needed in most advanced graphics applications.
NINJA: Java for High Performance Numerical Computing
Directory of Open Access Journals (Sweden)
José E. Moreira
2002-01-01
Full Text Available When Java was first introduced, there was a perception that its many benefits came at a significant performance cost. In the particularly performance-sensitive field of numerical computing, initial measurements indicated a hundred-fold performance disadvantage between Java and more established languages such as Fortran and C. Although much progress has been made, and Java now can be competitive with C/C++ in many important situations, significant performance challenges remain. Existing Java virtual machines are not yet capable of performing the advanced loop transformations and automatic parallelization that are now common in state-of-the-art Fortran compilers. Java also has difficulties in implementing complex arithmetic efficiently. These performance deficiencies can be attacked with a combination of class libraries (packages, in Java that implement truly multidimensional arrays and complex numbers, and new compiler techniques that exploit the properties of these class libraries to enable other, more conventional, optimizations. Two compiler techniques, versioning and semantic expansion, can be leveraged to allow fully automatic optimization and parallelization of Java code. Our measurements with the NINJA prototype Java environment show that Java can be competitive in performance with highly optimized and tuned Fortran code.
RISC Processors and High Performance Computing
Bailey, David H.; Saini, Subhash; Craw, James M. (Technical Monitor)
1995-01-01
This tutorial will discuss the top five RISC microprocessors and the parallel systems in which they are used. It will provide a unique cross-machine comparison not available elsewhere. The effective performance of these processors will be compared by citing standard benchmarks in the context of real applications. The latest NAS Parallel Benchmarks, both absolute performance and performance per dollar, will be listed. The next generation of the NPB will be described. The tutorial will conclude with a discussion of future directions in the field. Technology Transfer Considerations: All of these computer systems are commercially available internationally. Information about these processors is available in the public domain, mostly from the vendors themselves. The NAS Parallel Benchmarks and their results have been previously approved numerous times for public release, beginning back in 1991.
Energy Technology Data Exchange (ETDEWEB)
Baek, Seung Man [Seoul Nat' l Univ., Seoul (Korea, Republic of); Zhong, Yiming; Nam, Jin Hyun [Daegu Univ., Daegu (Korea, Republic of); Chung, Jae Dong [Sejong Univ., Seoul (Korea, Republic of); Hong, Hiki [Kyung Hee Univ., Seoul (Korea, Republic of)
2013-04-15
In a solar domestic hot water (Shadow) system, solar energy is collected using collector panels, transferred to a circulating heat transfer fluid (brine), and eventually stored in a thermal storage tank (Test) as hot water. In this study, a computational fluid dynamics (CAD) model was developed to predict the solar thermal energy storage in a hybrid type Test equipped with a helical jacket heater (mantle heat exchanger) and an immersed spiral coil heater. The helical jacket heater, which is the brine flow path attached to the side wall of a Test, has advantages including simple system design, low brine flow rate, and enhanced thermal stratification. In addition, the spiral coil heater further enhances the thermal performance and thermal stratification of the Test. The developed model was validated by the good agreement between the CAD results and the experimental results performed with the hybrid-type Test in Shadow settings.
International Nuclear Information System (INIS)
Baek, Seung Man; Zhong, Yiming; Nam, Jin Hyun; Chung, Jae Dong; Hong, Hiki
2013-01-01
In a solar domestic hot water (Shadow) system, solar energy is collected using collector panels, transferred to a circulating heat transfer fluid (brine), and eventually stored in a thermal storage tank (Test) as hot water. In this study, a computational fluid dynamics (CAD) model was developed to predict the solar thermal energy storage in a hybrid type Test equipped with a helical jacket heater (mantle heat exchanger) and an immersed spiral coil heater. The helical jacket heater, which is the brine flow path attached to the side wall of a Test, has advantages including simple system design, low brine flow rate, and enhanced thermal stratification. In addition, the spiral coil heater further enhances the thermal performance and thermal stratification of the Test. The developed model was validated by the good agreement between the CAD results and the experimental results performed with the hybrid-type Test in Shadow settings
Kindgen, Sarah; Wachtel, Herbert; Abrahamsson, Bertil; Langguth, Peter
2015-09-01
Disintegration of oral solid dosage forms is a prerequisite for drug dissolution and absorption and is to a large extent dependent on the pressures and hydrodynamic conditions in the solution that the dosage form is exposed to. In this work, the hydrodynamics in the PhEur/USP disintegration tester were investigated using computational fluid dynamics (CFD). Particle image velocimetry was used to validate the CFD predictions. The CFD simulations were performed with different Newtonian and non-Newtonian fluids, representing fasted and fed states. The results indicate that the current design and operating conditions of the disintegration test device, given by the pharmacopoeias, are not reproducing the in vivo situation. This holds true for the hydrodynamics in the disintegration tester that generates Reynolds numbers dissimilar to the reported in vivo situation. Also, when using homogenized US FDA meal, representing the fed state, too high viscosities and relative pressures are generated. The forces acting on the dosage form are too small for all fluids compared to the in vivo situation. The lack of peristaltic contractions, which generate hydrodynamics and shear stress in vivo, might be the major drawback of the compendial device resulting in the observed differences between predicted and in vivo measured hydrodynamics. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.
Littleton, Helen X; Daigger, Glen T; Strom, Peter F
2007-06-01
A full-scale, closed-loop bioreactor (Orbal oxidation ditch, Envirex brand technologies, Siemens, Waukesha, Wisconsin), previously examined for simultaneous biological nutrient removal (SBNR), was further evaluated using computational fluid dynamics (CFD). A CFD model was developed first by imparting the known momentum (calculated by tank fluid velocity and mass flowrate) to the fluid at the aeration disc region. Oxygen source (aeration) and sink (consumption) terms were introduced, and statistical analysis was applied to the CFD simulation results. The CFD model was validated with field data obtained from a test tank and a full-scale tank. The results indicated that CFD could predict the mixing pattern in closed-loop bioreactors. This enables visualization of the flow pattern, both with regard to flow velocity and dissolved-oxygen-distribution profiles. The velocity and oxygen-distribution gradients suggested that the flow patterns produced by directional aeration in closed-loop bioreactors created a heterogeneous environment that can result in dissolved oxygen variations throughout the bioreactor. Distinct anaerobic zones on a macroenvironment scale were not observed, but it is clear that, when flow passed around curves, a secondary spiral flow was generated. This second current, along with the main recirculation flow, could create alternating anaerobic and aerobic conditions vertically and horizontally, which would allow SBNR to occur. Reliable SBNR performance in Orbal oxidation ditches may be a result, at least in part, of such a spatially varying environment.
Byun, Chansup; Guruswamy, Guru P.; Kutler, Paul (Technical Monitor)
1994-01-01
In recent years significant advances have been made for parallel computers in both hardware and software. Now parallel computers have become viable tools in computational mechanics. Many application codes developed on conventional computers have been modified to benefit from parallel computers. Significant speedups in some areas have been achieved by parallel computations. For single-discipline use of both fluid dynamics and structural dynamics, computations have been made on wing-body configurations using parallel computers. However, only a limited amount of work has been completed in combining these two disciplines for multidisciplinary applications. The prime reason is the increased level of complication associated with a multidisciplinary approach. In this work, procedures to compute aeroelasticity on parallel computers using direct coupling of fluid and structural equations will be investigated for wing-body configurations. The parallel computer selected for computations is an Intel iPSC/860 computer which is a distributed-memory, multiple-instruction, multiple data (MIMD) computer with 128 processors. In this study, the computational efficiency issues of parallel integration of both fluid and structural equations will be investigated in detail. The fluid and structural domains will be modeled using finite-difference and finite-element approaches, respectively. Results from the parallel computer will be compared with those from the conventional computers using a single processor. This study will provide an efficient computational tool for the aeroelastic analysis of wing-body structures on MIMD type parallel computers.
Computer fan performance enhancement via acoustic perturbations
Energy Technology Data Exchange (ETDEWEB)
Greenblatt, David, E-mail: davidg@technion.ac.il [Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa (Israel); Avraham, Tzahi; Golan, Maayan [Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa (Israel)
2012-04-15
Highlights: Black-Right-Pointing-Pointer Computer fan effectiveness was increased by introducing acoustic perturbations. Black-Right-Pointing-Pointer Acoustic perturbations controlled blade boundary layer separation. Black-Right-Pointing-Pointer Optimum frequencies corresponded with airfoils studies. Black-Right-Pointing-Pointer Exploitation of flow instabilities was responsible for performance improvements. Black-Right-Pointing-Pointer Peak pressure and peak flowrate were increased by 40% and 15% respectively. - Abstract: A novel technique for increasing computer fan effectiveness, based on introducing acoustic perturbations onto the fan blades to control boundary layer separation, was assessed. Experiments were conducted in a specially designed facility that simultaneously allowed characterization of fan performance and introduction of the perturbations. A parametric study was conducted to determine the optimum control parameters, namely those that deliver the largest increase in fan pressure for a given flowrate. The optimum reduced frequencies corresponded with those identified on stationary airfoils and it was thus concluded that the exploitation of Kelvin-Helmholtz instabilities, commonly observed on airfoils, was responsible for the fan blade performance improvements. The optimum control inputs, such as acoustic frequency and sound pressure level, showed some variation with different fan flowrates. With the near-optimum control conditions identified, the full operational envelope of the fan, when subjected to acoustic perturbations, was assessed. The peak pressure and peak flowrate were increased by up to 40% and 15% respectively. The peak fan efficiency increased with acoustic perturbations but the overall system efficiency was reduced when the speaker input power was accounted for.
Computer fan performance enhancement via acoustic perturbations
International Nuclear Information System (INIS)
Greenblatt, David; Avraham, Tzahi; Golan, Maayan
2012-01-01
Highlights: ► Computer fan effectiveness was increased by introducing acoustic perturbations. ► Acoustic perturbations controlled blade boundary layer separation. ► Optimum frequencies corresponded with airfoils studies. ► Exploitation of flow instabilities was responsible for performance improvements. ► Peak pressure and peak flowrate were increased by 40% and 15% respectively. - Abstract: A novel technique for increasing computer fan effectiveness, based on introducing acoustic perturbations onto the fan blades to control boundary layer separation, was assessed. Experiments were conducted in a specially designed facility that simultaneously allowed characterization of fan performance and introduction of the perturbations. A parametric study was conducted to determine the optimum control parameters, namely those that deliver the largest increase in fan pressure for a given flowrate. The optimum reduced frequencies corresponded with those identified on stationary airfoils and it was thus concluded that the exploitation of Kelvin–Helmholtz instabilities, commonly observed on airfoils, was responsible for the fan blade performance improvements. The optimum control inputs, such as acoustic frequency and sound pressure level, showed some variation with different fan flowrates. With the near-optimum control conditions identified, the full operational envelope of the fan, when subjected to acoustic perturbations, was assessed. The peak pressure and peak flowrate were increased by up to 40% and 15% respectively. The peak fan efficiency increased with acoustic perturbations but the overall system efficiency was reduced when the speaker input power was accounted for.
Operation and Performance of the Supercritical Fluids Reactor (SFR)
National Research Council Canada - National Science Library
Hanush, R
1996-01-01
The Supercritical Fluids Reactor (SFR) at Sandia National Laboratories, CA has been developed to examine and solve engineering, process, and fundamental chemistry issues regarding the development of supercritical water oxidation (SCWO...
Aerodynamic study of state transport bus using computational fluid dynamics
Kanekar, Siddhesh; Thakre, Prashant; Rajkumar, E.
2017-11-01
The main purpose of this study was to develop the aerodynamic study of a Maharashtra state road transport bus. The rising fuel price and strict government regulations makes the road transport uneconomical now days. With the objective of increasing fuel efficiency and reducing the emission of harmful exhaust gases. It has been proven experimentally that vehicle consumes almost 40% of the available useful engine power to overcome the drag resistance. This provides us a huge scope to study the influence of aerodynamic drag. The initial of the project was to identify the drag coefficient of the existing ordinary type model called “Parivartan” from ANSYS fluent. After preliminary analysis of the existing model corresponding changes are made in such a way that their implementation should be possible at workshop level. The simulation of the air flow over the bus was performed in two steps: design on SolidWorks CAD and ANSYS (FLUENT) is used as a virtual analysis tool to estimate the drag coefficient of the bus. We have used the turbulence models k-ε Realizable having a better approximation of the actual result. Around 28% improvement in the drag coefficient is achieved by CFD driven changes in the bus design. Coefficient of drag is improved by 28% and fuel efficiency increased by 20% by CFD driven changes.
Application of computational fluid dynamics (CFD) to nuclear applications
International Nuclear Information System (INIS)
Brewster, R. A.; Jonnavithula, S.; Rizwan-Uddin; Rock, D. T.; Weber, D. P.; Wei, T. Y. C.
1999-01-01
Detailed analysis of a quarter channel was performed using VIPRE and CFX. Results show that VIPRE and CFX agree closely in both cross-sectionally averaged axial temperature and cross-sectionally averaged axial velocity profiles. Detailed temperature distributions in the radial direction over 1mm from the clad surface towards the center of the channel were calculated using CFX, showing significant local variation. This information can be used for example, to determine if this temperature will lead to bubble nucleation. Quarter subassembly calculations were made with both VIPRE and STAR-CD. Comparison between the solutions show that the two codes yield very similar solutions under comparable conditions. However, the STAR-CD CFD calculation provides the analyst with much more detailed flow and temperature distributions than can be predicted by a one-dimensional code such as VIPRE. In addition, a 60 million cell one-eighth reactor core calculation was made using STAR-CD. This analysis showed the importance of accurately predicting the flow and temperature fields in all assemblies simultaneously with modern parallel processing technology, practical turnaround for these types of calculation can be obtained
Computational modelling of the flow of viscous fluids in carbon nanotubes
Energy Technology Data Exchange (ETDEWEB)
Khosravian, N [Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Research in Fundamental Sciences (IPM), PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Rafii-Tabar, H [Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Research in Fundamental Sciences (IPM), PO Box 19395-5531, Tehran (Iran, Islamic Republic of)
2007-11-21
Carbon nanotubes will have extensive application in all areas of nano-technology, and in particular in the field of nano-fluidics, wherein they can be used for molecular separation, nano-scale filtering and as nano-pipes for conveying fluids. In the field of nano-medicine, nanotubes can be functionalized with various types of receptors to act as bio-sensors for the detection and elimination of cancer cells, or be used as bypasses and even neural connections. Modelling fluid flow inside nanotubes is a very challenging problem, since there is a complex interplay between the motion of the fluid and the stability of the walls. A critical issue in the design of nano-fluidic devices is the induced vibration of the walls, due to the fluid flow, which can promote structural instability. It has been established that the resonant frequencies depend on the flow velocity. We have studied, for the first time, the flow of viscous fluids through multi-walled carbon nanotubes, using the Euler-Bernoulli classical beam theory to model the nanotube as a continuum structure. Our aim has been to compute the effect of the fluid flow on the structural stability of the nanotubes, without having to consider the details of the fluid-walls interaction. The variations of the resonant frequencies with the flow velocity are obtained for both unembedded nanotubes, and when they are embedded in an elastic medium. It is found that a nanotube conveying a viscous fluid is more stable against vibration-induced buckling than a nanotube conveying a non-viscous fluid, and that the aspect ratio plays the same role in both cases.
Computational modelling of the flow of viscous fluids in carbon nanotubes
International Nuclear Information System (INIS)
Khosravian, N; Rafii-Tabar, H
2007-01-01
Carbon nanotubes will have extensive application in all areas of nano-technology, and in particular in the field of nano-fluidics, wherein they can be used for molecular separation, nano-scale filtering and as nano-pipes for conveying fluids. In the field of nano-medicine, nanotubes can be functionalized with various types of receptors to act as bio-sensors for the detection and elimination of cancer cells, or be used as bypasses and even neural connections. Modelling fluid flow inside nanotubes is a very challenging problem, since there is a complex interplay between the motion of the fluid and the stability of the walls. A critical issue in the design of nano-fluidic devices is the induced vibration of the walls, due to the fluid flow, which can promote structural instability. It has been established that the resonant frequencies depend on the flow velocity. We have studied, for the first time, the flow of viscous fluids through multi-walled carbon nanotubes, using the Euler-Bernoulli classical beam theory to model the nanotube as a continuum structure. Our aim has been to compute the effect of the fluid flow on the structural stability of the nanotubes, without having to consider the details of the fluid-walls interaction. The variations of the resonant frequencies with the flow velocity are obtained for both unembedded nanotubes, and when they are embedded in an elastic medium. It is found that a nanotube conveying a viscous fluid is more stable against vibration-induced buckling than a nanotube conveying a non-viscous fluid, and that the aspect ratio plays the same role in both cases
Synthetic lubricants and high-performance functional fluids
Rudnick, Leslie R
1999-01-01
Offers state-of-the-art information on all the major synthetic fluids, describing established products as well as highly promising experimental fluids with commercial potential. This second edition contains chapters on polyinternalolefins, polymer esters, refrigeration lubes, polyphenyl ethers, highly refined mineral oils, automotive gear oils and industrial gear oils. The book also assesses automotive, industrial, aerospace, environmental, and commercial trends in Europe, Asia, South America, and the US.
Atwood, Christopher A.
1993-01-01
The June 1992 to May 1993 grant NCC-2-677 provided for the continued demonstration of Computational Fluid Dynamics (CFD) as applied to the Stratospheric Observatory for Infrared Astronomy (SOFIA). While earlier grant years allowed validation of CFD through comparison against experiments, this year a new design proposal was evaluated. The new configuration would place the cavity aft of the wing, as opposed to the earlier baseline which was located immediately aft of the cockpit. This aft cavity placement allows for simplified structural and aircraft modification requirements, thus lowering the program cost of this national astronomy resource. Three appendices concerning this subject are presented.
High performance computations using dynamical nucleation theory
International Nuclear Information System (INIS)
Windus, T L; Crosby, L D; Kathmann, S M
2008-01-01
Chemists continue to explore the use of very large computations to perform simulations that describe the molecular level physics of critical challenges in science. In this paper, we describe the Dynamical Nucleation Theory Monte Carlo (DNTMC) model - a model for determining molecular scale nucleation rate constants - and its parallel capabilities. The potential for bottlenecks and the challenges to running on future petascale or larger resources are delineated. A 'master-slave' solution is proposed to scale to the petascale and will be developed in the NWChem software. In addition, mathematical and data analysis challenges are described
Computational Fluid Dynamics Prediction of a Modified Savonius Wind Turbine with Novel Blade Shapes
Directory of Open Access Journals (Sweden)
Wenlong Tian
2015-07-01
Full Text Available The Savonius wind turbine is a type of vertical axis wind turbine (VAWTs that is simply composed of two or three arc-type blades which can generate power even under poor wind conditions. A modified Savonius wind turbine with novel blade shapes is introduced with the aim of increasing the power coefficient of the turbine. The effect of blade fullness, which is a main shape parameter of the blade, on the power production of a two-bladed Savonius wind turbine is investigated using transient computational fluid dynamics (CFD. Simulations are based on the Reynolds Averaged Navier-Stokes (RANS equations with a renormalization group turbulent model. This numerical method is validated with existing experimental data and then utilized to quantify the performance of design variants. Results quantify the relationship between blade fullness and turbine performance with a blade fullness of 1 resulting in the highest coefficient of power, 0.2573. This power coefficient is 10.98% higher than a conventional Savonius turbine.
Computational fluid dynamics (CFD) simulation of a newly designed passive particle sampler.
Sajjadi, H; Tavakoli, B; Ahmadi, G; Dhaniyala, S; Harner, T; Holsen, T M
2016-07-01
In this work a series of computational fluid dynamics (CFD) simulations were performed to predict the deposition of particles on a newly designed passive dry deposition (Pas-DD) sampler. The sampler uses a parallel plate design and a conventional polyurethane foam (PUF) disk as the deposition surface. The deposition of particles with sizes between 0.5 and 10 μm was investigated for two different geometries of the Pas-DD sampler for different wind speeds and various angles of attack. To evaluate the mean flow field, the k-ɛ turbulence model was used and turbulent fluctuating velocities were generated using the discrete random walk (DRW) model. The CFD software ANSYS-FLUENT was used for performing the numerical simulations. It was found that the deposition velocity increased with particle size or wind speed. The modeled deposition velocities were in general agreement with the experimental measurements and they increased when flow entered the sampler with a non-zero angle of attack. The particle-size dependent deposition velocity was also dependent on the geometry of the leading edge of the sampler; deposition velocities were more dependent on particle size and wind speeds for the sampler without the bend in the leading edge of the deposition plate, compared to a flat plate design. Foam roughness was also found to have a small impact on particle deposition. Copyright © 2016 Elsevier Ltd. All rights reserved.
Analysis of parallel computing performance of the code MCNP
International Nuclear Information System (INIS)
Wang Lei; Wang Kan; Yu Ganglin
2006-01-01
Parallel computing can reduce the running time of the code MCNP effectively. With the MPI message transmitting software, MCNP5 can achieve its parallel computing on PC cluster with Windows operating system. Parallel computing performance of MCNP is influenced by factors such as the type, the complexity level and the parameter configuration of the computing problem. This paper analyzes the parallel computing performance of MCNP regarding with these factors and gives measures to improve the MCNP parallel computing performance. (authors)
Directory of Open Access Journals (Sweden)
Bogdanov Alexander
2016-01-01
Full Text Available The architecture of a digital computing system determines the technical foundation of a unified mathematical language for exact arithmetic-logical description of phenomena and laws of continuum mechanics for applications in fluid mechanics and theoretical physics. The deep parallelization of the computing processes results in functional programming at a new technological level, providing traceability of the computing processes with automatic application of multiscale hybrid circuits and adaptive mathematical models for the true reproduction of the fundamental laws of physics and continuum mechanics.
A parametric study of a solar calcinator using computational fluid dynamics
International Nuclear Information System (INIS)
Fidaros, D.K.; Baxevanou, C.A.; Vlachos, N.S.
2007-01-01
In this work a horizontal rotating solar calcinator is studied numerically using computational fluid dynamics. The specific solar reactor is a 10 kW model designed and used for efficiency studies. The numerical model is based on the solution of the Navier-Stokes equations for the gas flow, and on Lagrangean dynamics for the discrete particles. All necessary mathematical models were developed and incorporated into a computational fluid dynamics model with the influence of turbulence simulated by a two-equation (RNG k-ε) model. The efficiency of the reactor was calculated for different thermal inputs, feed rates, rotational speeds and particle diameters. The numerically computed degrees of calcination compared well with equivalent experimental results
DEFF Research Database (Denmark)
Wang, Weizhi; Wu, Minghao; Palm, Johannes
2018-01-01
for almost linear incident waves. First, we show that the computational fluid dynamics simulations have acceptable agreement to experimental data. We then present a verification and validation study focusing on the solution verification covering spatial and temporal discretization, iterative and domain......The wave loads and the resulting motions of floating wave energy converters are traditionally computed using linear radiation–diffraction methods. Yet for certain cases such as survival conditions, phase control and wave energy converters operating in the resonance region, more complete...... dynamics simulations have largely been overlooked in the wave energy sector. In this article, we apply formal verification and validation techniques to computational fluid dynamics simulations of a passively controlled point absorber. The phase control causes the motion response to be highly nonlinear even...
International Nuclear Information System (INIS)
Park, Jong Woon
2012-01-01
In Korean 3 Loop plants a water loop seal pipe is installed containing condensed water upstream of a pressurizer safety valve to protect the valve disk from the hot steam environment. The loop seal water purge time is a key parameter in safety analyses for overpressure transients, because it delays valve opening. The loop seal purge time is uncertain to measure by test and thus 3-dimensional realistic computational fluid dynamics (CFD) model is developed in this paper to predict the seal water purge time before full opening of the valve which is driven by steam after water purge. The CFD model for a typical pressurizer safety valve with a loop seal pipe is developed using the computer code of ANSYS CFX 11. Steady-state simulations are performed for full discharge of steam at the valve full opening. Transient simulations are performed for the loop seal dynamics and to estimate the loop seal purge time. A sudden pressure drop higher than 2,000 psia at the tip of the upper nozzle ring is expected from the steady-state calculation. Through the transient simulation, almost loop seal water is discharged within 1.2 second through the narrow opening between the disk and the nozzle of the valve. It can be expected that the valve fully opens at least before 1.2 second because constant valve opening is assumed in this CFX simulation, which is conservative because the valve opens fully before the loop seal water is completely discharged. The predicted loop seal purge time is compared with previous correlation. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Park, Jong Woon [Dongguk Univ., Gyeongju (Korea, Republic of). Nuclear and Energy Engineering Dept.
2012-11-15
In Korean 3 Loop plants a water loop seal pipe is installed containing condensed water upstream of a pressurizer safety valve to protect the valve disk from the hot steam environment. The loop seal water purge time is a key parameter in safety analyses for overpressure transients, because it delays valve opening. The loop seal purge time is uncertain to measure by test and thus 3-dimensional realistic computational fluid dynamics (CFD) model is developed in this paper to predict the seal water purge time before full opening of the valve which is driven by steam after water purge. The CFD model for a typical pressurizer safety valve with a loop seal pipe is developed using the computer code of ANSYS CFX 11. Steady-state simulations are performed for full discharge of steam at the valve full opening. Transient simulations are performed for the loop seal dynamics and to estimate the loop seal purge time. A sudden pressure drop higher than 2,000 psia at the tip of the upper nozzle ring is expected from the steady-state calculation. Through the transient simulation, almost loop seal water is discharged within 1.2 second through the narrow opening between the disk and the nozzle of the valve. It can be expected that the valve fully opens at least before 1.2 second because constant valve opening is assumed in this CFX simulation, which is conservative because the valve opens fully before the loop seal water is completely discharged. The predicted loop seal purge time is compared with previous correlation. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Pointer, William David [ORNL
2017-08-01
The objective of this effort is to establish a strategy and process for generation of suitable computational mesh for computational fluid dynamics simulations of departure from nucleate boiling in a 5 by 5 fuel rod assembly held in place by PWR mixing vane spacer grids. This mesh generation process will support ongoing efforts to develop, demonstrate and validate advanced multi-phase computational fluid dynamics methods that enable more robust identification of dryout conditions and DNB occurrence.Building upon prior efforts and experience, multiple computational meshes were developed using the native mesh generation capabilities of the commercial CFD code STAR-CCM+. These meshes were used to simulate two test cases from the Westinghouse 5 by 5 rod bundle facility. The sensitivity of predicted quantities of interest to the mesh resolution was then established using two evaluation methods, the Grid Convergence Index method and the Least Squares method. This evaluation suggests that the Least Squares method can reliably establish the uncertainty associated with local parameters such as vector velocity components at a point in the domain or surface averaged quantities such as outlet velocity magnitude. However, neither method is suitable for characterization of uncertainty in global extrema such as peak fuel surface temperature, primarily because such parameters are not necessarily associated with a fixed point in space. This shortcoming is significant because the current generation algorithm for identification of DNB event conditions relies on identification of such global extrema. Ongoing efforts to identify DNB based on local surface conditions will address this challenge
Evaluation of high-performance computing software
Energy Technology Data Exchange (ETDEWEB)
Browne, S.; Dongarra, J. [Univ. of Tennessee, Knoxville, TN (United States); Rowan, T. [Oak Ridge National Lab., TN (United States)
1996-12-31
The absence of unbiased and up to date comparative evaluations of high-performance computing software complicates a user`s search for the appropriate software package. The National HPCC Software Exchange (NHSE) is attacking this problem using an approach that includes independent evaluations of software, incorporation of author and user feedback into the evaluations, and Web access to the evaluations. We are applying this approach to the Parallel Tools Library (PTLIB), a new software repository for parallel systems software and tools, and HPC-Netlib, a high performance branch of the Netlib mathematical software repository. Updating the evaluations with feed-back and making it available via the Web helps ensure accuracy and timeliness, and using independent reviewers produces unbiased comparative evaluations difficult to find elsewhere.
Computer simulation is a useful tool for benchmarking the electrical and fuel energy consumption and water use in a fluid milk plant. In this study, a computer simulation model of the fluid milk process based on high temperature short time (HTST) pasteurization was extended to include models for pr...
Simanonok, K. E.; Srinivasan, R.; Charles, J. B.
1992-01-01
Fluid shifts in weightlessness may cause a central volume expansion, activating reflexes to reduce the blood volume. Computer simulation was used to test the hypothesis that preadaptation of the blood volume prior to exposure to weightlessness could counteract the central volume expansion due to fluid shifts and thereby attenuate the circulatory and renal responses resulting in large losses of fluid from body water compartments. The Guyton Model of Fluid, Electrolyte, and Circulatory Regulation was modified to simulate the six degree head down tilt that is frequently use as an experimental analog of weightlessness in bedrest studies. Simulation results show that preadaptation of the blood volume by a procedure resembling a blood donation immediately before head down bedrest is beneficial in damping the physiologic responses to fluid shifts and reducing body fluid losses. After ten hours of head down tilt, blood volume after preadaptation is higher than control for 20 to 30 days of bedrest. Preadaptation also produces potentially beneficial higher extracellular volume and total body water for 20 to 30 days of bedrest.
Computational fluid dynamics modeling of two-phase flow in a BWR fuel assembly
International Nuclear Information System (INIS)
Andrey Ioilev; Maskhud Samigulin; Vasily Ustinenko; Simon Lo; Adrian Tentner
2005-01-01
Full text of publication follows: The goal of this project is to develop an advanced Computational Fluid Dynamics (CFD) computer code (CFD-BWR) that allows the detailed analysis of the two-phase flow and heat transfer phenomena in a Boiling Water Reactor (BWR) fuel bundle under various operating conditions. This code will include more fundamental physical models than the current generation of sub-channel codes and advanced numerical algorithms for improved computational accuracy, robustness, and speed. It is highly desirable to understand the detailed two-phase flow phenomena inside a BWR fuel bundle. These phenomena include coolant phase changes and multiple flow regimes which directly influence the coolant interaction with fuel assembly and, ultimately, the reactor performance. Traditionally, the best analysis tools for the analysis of two-phase flow phenomena inside the BWR fuel assembly have been the sub-channel codes. However, the resolution of these codes is still too coarse for analyzing the detailed intra-assembly flow patterns, such as flow around a spacer element. Recent progress in Computational Fluid Dynamics (CFD), coupled with the rapidly increasing computational power of massively parallel computers, shows promising potential for the fine-mesh, detailed simulation of fuel assembly two-phase flow phenomena. However, the phenomenological models available in the commercial CFD programs are not as advanced as those currently being used in the sub-channel codes used in the nuclear industry. In particular, there are no models currently available which are able to reliably predict the nature of the flow regimes, and use the appropriate sub-models for those flow regimes. The CFD-BWR code is being developed as a customized module built on the foundation of the commercial CFD Code STAR-CD which provides general two-phase flow modeling capabilities. The paper describes the model development strategy which has been adopted by the development team for the
Energy Technology Data Exchange (ETDEWEB)
Williams, P. T. [Univ. of Tennessee, Knoxville, TN (United States)
1993-09-01
As the field of computational fluid dynamics (CFD) continues to mature, algorithms are required to exploit the most recent advances in approximation theory, numerical mathematics, computing architectures, and hardware. Meeting this requirement is particularly challenging in incompressible fluid mechanics, where primitive-variable CFD formulations that are robust, while also accurate and efficient in three dimensions, remain an elusive goal. This dissertation asserts that one key to accomplishing this goal is recognition of the dual role assumed by the pressure, i.e., a mechanism for instantaneously enforcing conservation of mass and a force in the mechanical balance law for conservation of momentum. Proving this assertion has motivated the development of a new, primitive-variable, incompressible, CFD algorithm called the Continuity Constraint Method (CCM). The theoretical basis for the CCM consists of a finite-element spatial semi-discretization of a Galerkin weak statement, equal-order interpolation for all state-variables, a 0-implicit time-integration scheme, and a quasi-Newton iterative procedure extended by a Taylor Weak Statement (TWS) formulation for dispersion error control. Original contributions to algorithmic theory include: (a) formulation of the unsteady evolution of the divergence error, (b) investigation of the role of non-smoothness in the discretized continuity-constraint function, (c) development of a uniformly H^{1} Galerkin weak statement for the Reynolds-averaged Navier-Stokes pressure Poisson equation, (d) derivation of physically and numerically well-posed boundary conditions, and (e) investigation of sparse data structures and iterative methods for solving the matrix algebra statements generated by the algorithm.
The path toward HEP High Performance Computing
Apostolakis, John; Carminati, Federico; Gheata, Andrei; Wenzel, Sandro
2014-01-01
High Energy Physics code has been known for making poor use of high performance computing architectures. Efforts in optimising HEP code on vector and RISC architectures have yield limited results and recent studies have shown that, on modern architectures, it achieves a performance between 10% and 50% of the peak one. Although several successful attempts have been made to port selected codes on GPUs, no major HEP code suite has a 'High Performance' implementation. With LHC undergoing a major upgrade and a number of challenging experiments on the drawing board, HEP cannot any longer neglect the less-than-optimal performance of its code and it has to try making the best usage of the hardware. This activity is one of the foci of the SFT group at CERN, which hosts, among others, the Root and Geant4 project. The activity of the experiments is shared and coordinated via a Concurrency Forum, where the experience in optimising HEP code is presented and discussed. Another activity is the Geant-V project, centred on th...
System and method for improving performance of a fluid sensor for an internal combustion engine
Kubinski, David [Canton, MI; Zawacki, Garry [Livonia, MI
2009-03-03
A system and method for improving sensor performance of an on-board vehicle sensor, such as an exhaust gas sensor, while sensing a predetermined substance in a fluid flowing through a pipe include a structure for extending into the pipe and having at least one inlet for receiving fluid flowing through the pipe and at least one outlet generally opposite the at least one inlet, wherein the structure redirects substantially all fluid flowing from the at least one inlet to the sensor to provide a representative sample of the fluid to the sensor before returning the fluid through the at least one outlet.
Investigation of Swirling Flow in Rod Bundle Subchannels Using Computational Fluid Dynamics
International Nuclear Information System (INIS)
Holloway, Mary V.; Beasley, Donald E.; Conner, Michael E.
2006-01-01
The fluid dynamics for turbulent flow through rod bundles representative of those used in pressurized water reactors is examined using computational fluid dynamics (CFD). The rod bundles of the pressurized water reactor examined in this study consist of a square array of parallel rods that are held on a constant pitch by support grids spaced axially along the rod bundle. Split-vane pair support grids are often used to create swirling flow in the rod bundle in an effort to improve the heat transfer characteristics for the rod bundle during both normal operating conditions and in accident condition scenarios. Computational fluid dynamics simulations for a two subchannel portion of the rod bundle were used to model the flow downstream of a split-vane pair support grid. A high quality computational mesh was used to investigate the choice of turbulence model appropriate for the complex swirling flow in the rod bundle subchannels. Results document a central swirling flow structure in each of the subchannels downstream of the split-vane pairs. Strong lateral flows along the surface of the rods, as well as impingement regions of lateral flow on the rods are documented. In addition, regions of lateral flow separation and low axial velocity are documented next to the rods. Results of the CFD are compared to experimental particle image velocimetry (PIV) measurements documenting the lateral flow structures downstream of the split-vane pairs. Good agreement is found between the computational simulation and experimental measurements for locations close to the support grid. (authors)
Directory of Open Access Journals (Sweden)
Yik Siang Pang
2018-01-01
Full Text Available This paper presents a Computational Fluid Dynamics (CFD study of a natural gas combustion burner focusing on the effect of combustion, thermal radiation and turbulence models on the temperature and chemical species concentration fields. The combustion was modelled using the finite rate/eddy dissipation (FR/EDM and partially premixed flame models. Detailed chemistry kinetics CHEMKIN GRI-MECH 3.0 consisting of 325 reactions was employed to model the methane combustion. Discrete ordinates (DO and spherical harmonics (P1 model were employed to predict the thermal radiation. The gas absorption coefficient dependence on the wavelength is resolved by the weighted-sum-of-gray-gases model (WSGGM. Turbulence flow was simulated using Reynolds-averaged Navier-Stokes (RANS based models. The findings showed that a combination of partially premixed flame, P1 and standard k-ε (SKE gave the most accurate prediction with an average deviation of around 7.8% of combustion temperature and 15.5% for reactant composition (methane and oxygen. The results show the multi-step chemistry in the partially premixed model is more accurate than the two-step FR/EDM. Meanwhile, inclusion of thermal radiation has a minor effect on the heat transfer and species concentration. SKE turbulence model yielded better prediction compared to the realizable k-ε (RKE and renormalized k-ε (RNG. The CFD simulation presented in this work may serve as a useful tool to evaluate a performance of a natural gas combustor. Copyright © 2018 BCREC Group. All rights reserved Received: 26th July 2017; Revised: 9th October 2017; Accepted: 30th October 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Pang, Y.S., Law, W.P., Pung, K.Q., Gimbun, J. (2018. A Computational Fluid Dynamics Study of Turbulence, Radiation, and Combustion Models for Natural Gas Combustion Burner. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1: 155-169 (doi:10.9767/bcrec
Park, Soonchan; Lee, Sang-Wook; Lim, Ok Kyun; Min, Inki; Nguyen, Minhtuan; Ko, Young Bae; Yoon, Kyunghwan; Suh, Dae Chul
2013-02-01
Image-based computational models with fluid-structure interaction (FSI) can be used to perform plaque mechanical analysis in intracranial artery stenosis. We described a process in FSI study applied to symptomatic severe intracranial (M1) stenosis before and after stenting. Reconstructed 3D angiography in STL format was transferred to Magics for smoothing of vessel surface and trimming of branch vessels and to HyperMesh for generating tetra volume mesh from triangular surface-meshed 3D angiogram. Computational analysis of blood flow in the blood vessels was performed using the commercial finite element software ADINA Ver 8.5. The distribution of wall shear stress (WSS), peak velocity and pressure was analyzed before and after intracranial stenting. The wall shear stress distributions from Computational fluid dynamics (CFD) simulation with rigid wall assumption as well as FSI simulation before and after stenting could be compared. The difference of WSS between rigid wall and compliant wall model both in pre- and post-stent case is only minor except at the stenosis region. These WSS values were greatly reduced after stenting to 15~20 Pa at systole and 3~5 Pa at end-diastole in CFD simulation, which are similar in FSI simulations. Our study revealed that FSI simulation before and after intracranial stenting was feasible despite of limited vessel wall dimension and could reveal change of WSS as well as flow velocity and wall pressure.
Computational Fluid Dynamics based Fault Simulations of a Vertical Axis Wind Turbines
International Nuclear Information System (INIS)
Park, Kyoo-seon; Asim, Taimoor; Mishra, Rakesh
2012-01-01
Due to depleting fossil fuels and a rapid increase in the fuel prices globally, the search for alternative energy sources is becoming more and more significant. One of such energy source is the wind energy which can be harnessed with the use of wind turbines. The fundamental principle of wind turbines is to convert the wind energy into first mechanical and then into electrical form. The relatively simple operation of such turbines has stirred the researchers to come up with innovative designs for global acceptance and to make these turbines commercially viable. Furthermore, the maintenance of wind turbines has long been a topic of interest. Condition based monitoring of wind turbines is essential to maintain continuous operation of wind turbines. The present work focuses on the difference in the outputs of a vertical axis wind turbine (VAWT) under different operational conditions. A Computational Fluid Dynamics (CFD) technique has been used for various blade configurations of a VAWT. The results indicate that there is significant degradation in the performance output of wind turbines as the number of blades broken or missing from the VAWT increases. The study predicts the faults in the blades of VAWTs by monitoring its output.
Computational fluid dynamic simulations of coal-fired utility boilers: An engineering tool
Energy Technology Data Exchange (ETDEWEB)
Efim Korytnyi; Roman Saveliev; Miron Perelman; Boris Chudnovsky; Ezra Bar-Ziv [Ben-Gurion University of the Negev, Beer-Sheva (Israel)
2009-01-15
The objective of this study was to develop an engineering tool by which the combustion behavior of coals in coal-fired utility boilers can be predicted. We presented in this paper that computational fluid dynamic (CFD) codes can successfully predict performance of - and emission from - full-scale pulverized-coal utility boilers of various types, provided that the model parameters required for the simulation are properly chosen and validated. For that purpose we developed a methodology combining measurements in a 50 kW pilot-scale test facility with CFD simulations using the same CFD code configured for both test and full-scale furnaces. In this method model parameters of the coal processes are extracted and validated. This paper presents the importance of the validation of the model parameters which are used in CFD codes. Our results show very good fit of CFD simulations with various parameters measured in a test furnace and several types of utility boilers. The results of this study demonstrate the viability of the present methodology as an effective tool for optimization coal burning in full-scale utility boilers. 41 refs., 9 figs., 3 tabs.
Directory of Open Access Journals (Sweden)
JUNG-SIK CHOI
2014-06-01
Full Text Available In this study, we proposed a newly designed sulfuric acid transfer system for the sulfur-iodine (SI thermochemical cycle. The proposed sulfuric acid transfer system was evaluated using a computational fluid dynamics (CFD analysis for investigating thermodynamic/hydrodynamic characteristics and material properties. This analysis was conducted to obtain reliable continuous operation parameters; in particular, a thermal analysis was performed on the bellows box and bellows at amplitudes and various frequencies (0.1, 0.5, and 1.0 Hz. However, the high temperatures and strongly corrosive operating conditions of the current sulfuric acid system present challenges with respect to the structural materials of the transfer system. To resolve this issue, we designed a novel transfer system using polytetrafluoroethylene (PTFE, Teflon® as a bellows material for the transfer of sulfuric acid. We also carried out a CFD analysis of the design. The CFD results indicated that the maximum applicable temperature of PTFE is about 533 K (260 °C, even though its melting point is around 600 K. This result implies that the PTFE is a potential material for the sulfuric acid transfer system. The CFD simulations also confirmed that the sulfuric acid transfer system was designed properly for this particular investigation.
Rodrigues, Nelson J O; Oliveira, Ricardo F; Teixeira, Senhorinha F C F; Miguel, Alberto Sérgio; Teixeira, José Carlos; Baptista, João S
2015-01-01
Studies concerning indoor thermal conditions are very important in defining the satisfactory comfort range in health care facilities. This study focuses on the evaluation of the thermal comfort sensation felt by surgeons and nurses, in an orthopaedic surgical room of a Portuguese hospital. Two cases are assessed, with and without the presence of a person. Computational fluid dynamic (CFD) tools were applied for evaluating the predicted mean vote (PMV) index locally. Using average ventilation values to calculate the PMV index does not provide a correct and enough descriptive evaluation of the surgical room thermal environment. As studied for both cases, surgeons feel the environment slightly hotter than nurses. The nurses feel a slightly cold sensation under the air supply diffuser and their neutral comfort zone is located in the air stagnation zones close to the walls, while the surgeons feel the opposite. It was observed that the presence of a person in the room leads to an increase of the PMV index for surgeons and nurses. That goes in line with the empirical knowledge that more persons in a room lead to an increased heat sensation. The clothing used by both classes, as well as the ventilation conditions, should be revised accordingly to the amount of persons in the room and the type of activity performed.
Qiao, Aike; Dai, Xuan; Niu, Jing; Jiao, Liqun
2016-01-01
Hemodynamic factors may affect the potential occurrence of in-stent restenosis (ISR) after intervention procedure of vertebral artery ostial stenosis (VAOS). The purpose of the present study is to investigate the influence of stent protrusion length in implantation strategy on the local hemodynamics of the VAOS. CTA images of a 58-year-old female patient with posterior circulation transient ischemic attack were used to perform a 3D reconstruction of the vertebral artery. Five models of the vertebral artery before and after the stent implantation were established. Model 1 was without stent implantation, Model 2-5 was with stent protruding into the subclavian artery for 0, 1, 2, 3 mm, respectively. Computational fluid dynamics simulations based on finite element analysis were employed to mimic the blood flow in arteries and to assess hemodynamic conditions, particularly the blood flow velocity and wall shear stress (WSS). The WSS and the blood flow velocity at the vertebral artery ostium were reduced by 85.33 and 35.36% respectively after stents implantation. The phenomenon of helical flow disappeared. Hemodynamics comparison showed that stent struts that protruded 1 mm into the subclavian artery induced the least decrease in blood speed and WSS. The results suggest that stent implantation can improve the hemodynamics of VAOS, while stent struts that had protruded 1 mm into the subclavian artery would result in less thrombogenesis and neointimal hyperplasia and most likely decrease the risk of ISR.
Cano, Grégory; Mouahid, Adil; Carretier, Emilie; Guasp, Pascal; Dhaler, Didier; Castelas, Bernard; Moulin, Philippe
2015-01-01
The aim of this study is to apply the membrane bioreactor technology in an oxidation ditch in submerged conditions. This new wastewater filtration process will benefit rural areas (membranes developed without support are immersed in an aeration well and work in suction mode. The development of the membrane without support and more precisely the performance of spacers are approached by computational fluid dynamics in order to provide the best compromise between pressure drop/flow velocity and permeate flux. The numerical results on the layout and the membrane modules' geometry in the aeration well indicate that the optimal configuration is to install the membranes horizontally on three levels. Membranes should be connected to each other to a manifold providing a total membrane area of 18 m². Loss rate compared to the theoretical throughput is relatively low (less than 3%). Preliminary data obtained by modeling the lagoon provide access to its hydrodynamics, revealing that recirculation zones can be optimized by making changes in the operating conditions. The experimental validation of these results and taking into account the aeration in the numerical models are underway.
Optimization of a Continuous Hybrid Impeller Mixer via Computational Fluid Dynamics
Directory of Open Access Journals (Sweden)
N. Othman
2014-01-01
Full Text Available This paper presents the preliminary steps required for conducting experiments to obtain the optimal operating conditions of a hybrid impeller mixer and to determine the residence time distribution (RTD using computational fluid dynamics (CFD. In this paper, impeller speed and clearance parameters are examined. The hybrid impeller mixer consists of a single Rushton turbine mounted above a single pitched blade turbine (PBT. Four impeller speeds, 50, 100, 150, and 200 rpm, and four impeller clearances, 25, 50, 75, and 100 mm, were the operation variables used in this study. CFD was utilized to initially screen the parameter ranges to reduce the number of actual experiments needed. Afterward, the residence time distribution (RTD was determined using the respective parameters. Finally, the Fluent-predicted RTD and the experimentally measured RTD were compared. The CFD investigations revealed that an impeller speed of 50 rpm and an impeller clearance of 25 mm were not viable for experimental investigations and were thus eliminated from further analyses. The determination of RTD using a k-ε turbulence model was performed using CFD techniques. The multiple reference frame (MRF was implemented and a steady state was initially achieved followed by a transient condition for RTD determination.
Optimization of a continuous hybrid impeller mixer via computational fluid dynamics.
Othman, N; Kamarudin, S K; Takriff, M S; Rosli, M I; Engku Chik, E M F; Meor Adnan, M A K
2014-01-01
This paper presents the preliminary steps required for conducting experiments to obtain the optimal operating conditions of a hybrid impeller mixer and to determine the residence time distribution (RTD) using computational fluid dynamics (CFD). In this paper, impeller speed and clearance parameters are examined. The hybrid impeller mixer consists of a single Rushton turbine mounted above a single pitched blade turbine (PBT). Four impeller speeds, 50, 100, 150, and 200 rpm, and four impeller clearances, 25, 50, 75, and 100 mm, were the operation variables used in this study. CFD was utilized to initially screen the parameter ranges to reduce the number of actual experiments needed. Afterward, the residence time distribution (RTD) was determined using the respective parameters. Finally, the Fluent-predicted RTD and the experimentally measured RTD were compared. The CFD investigations revealed that an impeller speed of 50 rpm and an impeller clearance of 25 mm were not viable for experimental investigations and were thus eliminated from further analyses. The determination of RTD using a k-ε turbulence model was performed using CFD techniques. The multiple reference frame (MRF) was implemented and a steady state was initially achieved followed by a transient condition for RTD determination.
Optimal design of wind barriers using 3D computational fluid dynamics simulations
Fang, H.; Wu, X.; Yang, X.
2017-12-01
Desertification is a significant global environmental and ecological problem that requires human-regulated control and management. Wind barriers are commonly used to reduce wind velocity or trap drifting sand in arid or semi-arid areas. Therefore, optimal design of wind barriers becomes critical in Aeolian engineering. In the current study, we perform 3D computational fluid dynamics (CFD) simulations for flow passing through wind barriers with different structural parameters. To validate the simulation results, we first inter-compare the simulated flow field results with those from both wind-tunnel experiments and field measurements. Quantitative analyses of the shelter effect are then conducted based on a series of simulations with different structural parameters (such as wind barrier porosity, row numbers, inter-row spacing and belt schemes). The results show that wind barriers with porosity of 0.35 could provide the longest shelter distance (i.e., where the wind velocity reduction is more than 50%) thus are recommended in engineering designs. To determine the optimal row number and belt scheme, we introduce a cost function that takes both wind-velocity reduction effects and economical expense into account. The calculated cost function show that a 3-row-belt scheme with inter-row spacing of 6h (h as the height of wind barriers) and inter-belt spacing of 12h is the most effective.
Jafarian, Yaser; Ghorbani, Ali; Ahmadi, Omid
2014-09-01
Lateral deformation of liquefiable soil is a cause of much damage during earthquakes, reportedly more than other forms of liquefaction-induced ground failures. Researchers have presented studies in which the liquefied soil is considered as viscous fluid. In this manner, the liquefied soil behaves as non-Newtonian fluid, whose viscosity decreases as the shear strain rate increases. The current study incorporates computational fluid dynamics to propose a simplified dynamic analysis for the liquefaction-induced lateral deformation of earth slopes. The numerical procedure involves a quasi-linear elastic model for small to moderate strains and a Bingham fluid model for large strain states during liquefaction. An iterative procedure is considered to estimate the strain-compatible shear stiffness of soil. The post-liquefaction residual strength of soil is considered as the initial Bingham viscosity. Performance of the numerical procedure is examined by using the results of centrifuge model and shaking table tests together with some field observations of lateral ground deformation. The results demonstrate that the proposed procedure predicts the time history of lateral ground deformation with a reasonable degree of precision.
Energy Technology Data Exchange (ETDEWEB)
Braz Filho, Francisco A.; Caldeira, Alexandre D.; Borges, Eduardo M., E-mail: fbraz@ieav.cta.b, E-mail: alexdc@ieav.cta.b, E-mail: eduardo@ieav.cta.b [Instituto de Estudos Avancados (IEAv/CTA), Sao Jose dos Campos, SP (Brazil). Div. de Energia Nuclear
2011-07-01
In a heated vertical channel, the subcooled flow boiling regime occurs when the bulk fluid temperature is lower than the saturation temperature, but the fluid temperature reaches the saturation point near the channel wall. This phenomenon produces a significant increase in heat flux, limited by the critical heat flux. This study is particularly important to the thermal-hydraulics analysis of pressurized water reactors. The purpose of this work is the validation of a multidimensional model to analyze the subcooled flow boiling comparing the results with experimental data found in literature. The computational fluid dynamics code FLUENT was used with Eulerian multiphase model option. The calculated values of wall temperature in the liquid-solid interface presented an excellent agreement when compared to the experimental data. Void fraction calculations presented satisfactory results in relation to the experimental data in pressures of 15, 30 and 45 bars. (author)
Moving on to the modeling and simulation using computational fluid dynamics
International Nuclear Information System (INIS)
Norasalwa Zakaria; Rohyiza Baan; Muhd Noor Muhd Yunus
2006-01-01
The heat is on but not at the co-combustor plant. Using the Computational Fluid Dynamics (CFD), modeling and simulation of an incinerator has been made easy and possible from the comfort of cozy room. CFD has become an important design tool in nearly every industrial field because it provides understanding of flow patterns. CFD provide values for fluid velocity, fluid temperature, pressure and species concentrations throughout a flow domain. MINT has acquired a complete CFD software recently, consisting of GAMBIT, which is use to build geometry and meshing, and FLUENT as the processor or solver. This paper discusses on several trial runs that was carried out on several parts of the co-combustor plant namely the under fire section and the mixing chamber section
International Nuclear Information System (INIS)
Braz Filho, Francisco A.; Caldeira, Alexandre D.; Borges, Eduardo M.
2011-01-01
In a heated vertical channel, the subcooled flow boiling regime occurs when the bulk fluid temperature is lower than the saturation temperature, but the fluid temperature reaches the saturation point near the channel wall. This phenomenon produces a significant increase in heat flux, limited by the critical heat flux. This study is particularly important to the thermal-hydraulics analysis of pressurized water reactors. The purpose of this work is the validation of a multidimensional model to analyze the subcooled flow boiling comparing the results with experimental data found in literature. The computational fluid dynamics code FLUENT was used with Eulerian multiphase model option. The calculated values of wall temperature in the liquid-solid interface presented an excellent agreement when compared to the experimental data. Void fraction calculations presented satisfactory results in relation to the experimental data in pressures of 15, 30 and 45 bars. (author)
A High Performance COTS Based Computer Architecture
Patte, Mathieu; Grimoldi, Raoul; Trautner, Roland
2014-08-01
Using Commercial Off The Shelf (COTS) electronic components for space applications is a long standing idea. Indeed the difference in processing performance and energy efficiency between radiation hardened components and COTS components is so important that COTS components are very attractive for use in mass and power constrained systems. However using COTS components in space is not straightforward as one must account with the effects of the space environment on the COTS components behavior. In the frame of the ESA funded activity called High Performance COTS Based Computer, Airbus Defense and Space and its subcontractor OHB CGS have developed and prototyped a versatile COTS based architecture for high performance processing. The rest of the paper is organized as follows: in a first section we will start by recapitulating the interests and constraints of using COTS components for space applications; then we will briefly describe existing fault mitigation architectures and present our solution for fault mitigation based on a component called the SmartIO; in the last part of the paper we will describe the prototyping activities executed during the HiP CBC project.
Weingart, Robert
This thesis is about the validation of a computational fluid dynamics simulation of a ground vehicle by means of a low-budget coast-down test. The vehicle is built to the standards of the 2014 Formula SAE rules. It is equipped with large wings in the front and rear of the car; the vertical loads on the tires are measured by specifically calibrated shock potentiometers. The coast-down test was performed on a runway of a local airport and is used to determine vehicle specific coefficients such as drag, downforce, aerodynamic balance, and rolling resistance for different aerodynamic setups. The test results are then compared to the respective simulated results. The drag deviates about 5% from the simulated to the measured results. The downforce numbers show a deviation up to 18% respectively. Moreover, a sensitivity analysis of inlet velocities, ride heights, and pitch angles was performed with the help of the computational simulation.
Performance evaluation of a computed radiography system
Energy Technology Data Exchange (ETDEWEB)
Roussilhe, J.; Fallet, E. [Carestream Health France, 71 - Chalon/Saone (France); Mango, St.A. [Carestream Health, Inc. Rochester, New York (United States)
2007-07-01
Computed radiography (CR) standards have been formalized and published in Europe and in the US. The CR system classification is defined in those standards by - minimum normalized signal-to-noise ratio (SNRN), and - maximum basic spatial resolution (SRb). Both the signal-to-noise ratio (SNR) and the contrast sensitivity of a CR system depend on the dose (exposure time and conditions) at the detector. Because of their wide dynamic range, the same storage phosphor imaging plate can qualify for all six CR system classes. The exposure characteristics from 30 to 450 kV, the contrast sensitivity, and the spatial resolution of the KODAK INDUSTREX CR Digital System have been thoroughly evaluated. This paper will present some of the factors that determine the system's spatial resolution performance. (authors)
International Nuclear Information System (INIS)
Borges, E.M.
1991-01-01
Thermoelectric Electromagnetic (TEEM) Pumps can be used for controlling the fluid flow in the primary and secondary circuits of liquid metal cooled space nuclear reactor. In order to simulate and to evaluate the pumps performance, in steady-state, the computer program BEMTE has been developed to study the main operational parameters and to determine the system actuation point, for a given reactor operating power. The results for each stage of the program were satisfactory, compared to experimental data. The program shows to be adequate for the design and simulating of direct current electromagnetic pumps. (author)
Evaluation of Thermo-Fluid Performance of Compact Heat Exchanger with Corrugated Wall Channels
International Nuclear Information System (INIS)
Tak, Nam Il; Lee, Won Jae
2006-01-01
One of the key components of an indirect nuclear hydrogen production system is an intermediate heat exchanger (IHX). For the IHX, a printed circuit heat exchanger (PCHE) is known as one of the promising types due to its compactness and ability to operate at high temperatures and under high pressures. The PCHE is a relatively new heat exchanger. It has been commercially manufactured only since 1985 and solely by one British vendor, HeatricTM. Due to its short history and limited production, sufficient information about the PCHE is not available for the design of the IHX in open literatures. The predominant shape of flow channels of the PCHE is laterally corrugated. The flow in a corrugated wall channel is very interesting since a variety of flow phenomena can be considered by changing the amplitude-to-wavelength ratio. In the present paper, thermo-fluid performance of a heat exchanger with a typical PCHE geometry has been evaluated. Computational fluid dynamics (CFD) analysis was performed to analyze a gas flow behavior in a corrugated wall channel
A simplified computational fluid-dynamic approach to the oxidizer injector design in hybrid rockets
Di Martino, Giuseppe D.; Malgieri, Paolo; Carmicino, Carmine; Savino, Raffaele
2016-12-01
Fuel regression rate in hybrid rockets is non-negligibly affected by the oxidizer injection pattern. In this paper a simplified computational approach developed in an attempt to optimize the oxidizer injector design is discussed. Numerical simulations of the thermo-fluid-dynamic field in a hybrid rocket are carried out, with a commercial solver, to investigate into several injection configurations with the aim of increasing the fuel regression rate and minimizing the consumption unevenness, but still favoring the establishment of flow recirculation at the motor head end, which is generated with an axial nozzle injector and has been demonstrated to promote combustion stability, and both larger efficiency and regression rate. All the computations have been performed on the configuration of a lab-scale hybrid rocket motor available at the propulsion laboratory of the University of Naples with typical operating conditions. After a preliminary comparison between the two baseline limiting cases of an axial subsonic nozzle injector and a uniform injection through the prechamber, a parametric analysis has been carried out by varying the oxidizer jet flow divergence angle, as well as the grain port diameter and the oxidizer mass flux to study the effect of the flow divergence on heat transfer distribution over the fuel surface. Some experimental firing test data are presented, and, under the hypothesis that fuel regression rate and surface heat flux are proportional, the measured fuel consumption axial profiles are compared with the predicted surface heat flux showing fairly good agreement, which allowed validating the employed design approach. Finally an optimized injector design is proposed.
Schwing, Alan Michael
For computational fluid dynamics, the governing equations are solved on a discretized domain of nodes, faces, and cells. The quality of the grid or mesh can be a driving source for error in the results. While refinement studies can help guide the creation of a mesh, grid quality is largely determined by user expertise and understanding of the flow physics. Adaptive mesh refinement is a technique for enriching the mesh during a simulation based on metrics for error, impact on important parameters, or location of important flow features. This can offload from the user some of the difficult and ambiguous decisions necessary when discretizing the domain. This work explores the implementation of adaptive mesh refinement in an implicit, unstructured, finite-volume solver. Consideration is made for applying modern computational techniques in the presence of hanging nodes and refined cells. The approach is developed to be independent of the flow solver in order to provide a path for augmenting existing codes. It is designed to be applicable for unsteady simulations and refinement and coarsening of the grid does not impact the conservatism of the underlying numerics. The effect on high-order numerical fluxes of fourth- and sixth-order are explored. Provided the criteria for refinement is appropriately selected, solutions obtained using adapted meshes have no additional error when compared to results obtained on traditional, unadapted meshes. In order to leverage large-scale computational resources common today, the methods are parallelized using MPI. Parallel performance is considered for several test problems in order to assess scalability of both adapted and unadapted grids. Dynamic repartitioning of the mesh during refinement is crucial for load balancing an evolving grid. Development of the methods outlined here depend on a dual-memory approach that is described in detail. Validation of the solver developed here against a number of motivating problems shows favorable
A code to compute borehole fluid conductivity profiles with multiple feed points
International Nuclear Information System (INIS)
Hale, F.V.; Tsang, C.F.
1988-03-01
It is of much current interest to determine the flow characteristics of fractures intersecting a wellbore in order to understand the hydrologic behavior of fractured rocks. Often inflow from these fractures into the wellbore is at very low rates. A new procedure has been proposed and a corresponding method of analysis developed to obtain fracture inflow parameters from a time sequence of electric conductivity logs of the borehole fluid. The present report is a companion document to NTB--88-13 giving the details of equations and computer code used to compute borehole fluid conductivity distributions. Verification of the code used and a listing of the code are also given. (author) 9 refs., 5 figs., 7 tabs
Optimization high vortex finder of cyclone separator with computational fluids dynamics simulation
Directory of Open Access Journals (Sweden)
Ni Ketut Caturwati
2017-01-01
Full Text Available Cyclone separator is an equipment that separates particles contained in the fluid without using filters. The dust particles in the flue gases can be separated by utilizing centrifugal forces and different densities of particles, so that the exhaust gases to be cleaner before discharged into the environment. In this paper carried out a simulation by Computational of Fluids Dynamics to determine the number of particles that can be separated in several cyclone separator which has a ratio body diameter against vortex finder high varied as : 1:0.5 ; 1:0.75 ; 1:1 ; 1:1.25 and 1:1.5. Fluid inlet are air with antrachite impurity particles that are commonly found in the exhaust gases from tire manufacturers with inlet velocities varied as: 15 m/s and 30 m/s. The results of simulation show the fluids with 15 m/s of inlet velocity is generate particle separation value is higher than the fluids with 30 m/s inlet velocity for ratio of body diameter and height vortex finder a: 1:0.5 and 1:1.5. For both of inlet velocities the best ratio of body diameter and height vortex finder is 1:1.25, where it has the highest values of percentage trapped particles about 86% for 30 m/s input velocity and also for 15 m/s input velocity.
Prediction of velocity and attitude of a yacht sailing upwind by computational fluid dynamics
Lee, Heebum; Park, Mi Yeon; Park, Sunho; Rhee, Shin Hyung
2016-01-01
One of the most important factors in sailing yacht design is accurate velocity prediction. Velocity prediction programs (VPP's) are widely used to predict velocity of sailing yachts. VPP's, which are primarily based on experimental data and experience of long years, however suffer limitations when applied in realistic conditions. Thus, in the present study, a high fidelity velocity prediction method using computational fluid dynamics (CFD) was proposed. Using the developed method, velocity an...
Ding X. R.; Guo Y. Y.; Chen Y. Y.
2017-01-01
This study aims to design a novel air cleaning facility which conforms to the current situation in China, and moreover can satisfy our demand on air purification under the condition of poor air quality, as well as discuss the development means of a prototype product. Air conditions in the operating room of a hospital were measured as the research subject of this study. First, a suitable turbulence model and boundary conditions were selected and computational fluid dynamics (CFD) software was ...
International Nuclear Information System (INIS)
Koski, J.A.; Wix, S.D.; Cole, J.K.
1997-09-01
Shipboard fires both in the same ship hold and in an adjacent hold aboard a break-bulk cargo ship are simulated with a commercial finite-volume computational fluid mechanics code. The fire models and modeling techniques are described and discussed. Temperatures and heat fluxes to a simulated materials package are calculated and compared to experimental values. The overall accuracy of the calculations is assessed
The NASA Computational Fluid Dynamics (CFD) program - Building technology to solve future challenges
Richardson, Pamela F.; Dwoyer, Douglas L.; Kutler, Paul; Povinelli, Louis A.
1993-01-01
This paper presents the NASA Computational Fluid Dynamics program in terms of a strategic vision and goals as well as NASA's financial commitment and personnel levels. The paper also identifies the CFD program customers and the support to those customers. In addition, the paper discusses technical emphasis and direction of the program and some recent achievements. NASA's Ames, Langley, and Lewis Research Centers are the research hubs of the CFD program while the NASA Headquarters Office of Aeronautics represents and advocates the program.
Computational Fluid Dynamics (CFD) investigation onto passenger car disk brake design
International Nuclear Information System (INIS)
Munisamy, Kannan M; Moorthy, Shangkari K Kanasan
2013-01-01
The aim of this study is to investigate the flow and heat transfer in ventilated disc brakes using Computational Fluid Dynamics (CFD). NACA Series blade is designed for ventilated disc brake and the cooling characteristic is compared to the baseline design. The ventilated disc brakes are simulated using commercial CFD software FLUENT TM using simulation configuration that was obtained from experiment data. The NACA Series blade design shows improvements in Nusselt number compared to baseline design.
Computational Fluid Dynamics (CFD) investigation onto passenger car disk brake design
Munisamy, Kannan M.; Kanasan Moorthy, Shangkari K.
2013-06-01
The aim of this study is to investigate the flow and heat transfer in ventilated disc brakes using Computational Fluid Dynamics (CFD). NACA Series blade is designed for ventilated disc brake and the cooling characteristic is compared to the baseline design. The ventilated disc brakes are simulated using commercial CFD software FLUENTTM using simulation configuration that was obtained from experiment data. The NACA Series blade design shows improvements in Nusselt number compared to baseline design.
Kaiser, Stephan Christian
2015-01-01
Durch die örtliche und zeitliche Modellierung der auftretenden Strömungen bietet die numerische Fluiddynamik (engl. Computational Fluid Dynamics, CFD) das Potenzial detaillierte Untersuchungen der Hydrodynamik in Bioreaktoren durchzuführen. Allerdings sind bisher nur wenige Studien in Verbindung mit Einwegbioreaktoren, die sich durch konstruktiven Besonderheiten von ihren klassischen Gegenspielern aus Glas und/oder Edelstahl unterscheiden, publiziert. Die vorliegende Arbeit soll daher geeigne...
Directory of Open Access Journals (Sweden)
P. Karthik
2015-12-01
Full Text Available The present study aimed to perform the parametric analysis on thermo-hydraulic performance of a compact heat exchanger using computational fluid dynamics (CFD. The analysis has been carried out at different frontal air velocities by varying the geometrical parameters such as fin pitch, transverse tube pitch, longitudinal tube pitch, louver pitch and louver angle. The air side performance of the heat exchanger has been evaluated by calculating Colburn factor (j and Fanning friction factor (f. The comparison of CFD results with the experimental data exhibited a good agreement and the influence of various geometrical parameters for the selected range of values on the pressure drop, heat transfer coefficient and goodness factor was analyzed. The results obtained from the analysis will be very useful to optimize the louvered fin and flat tube compact heat exchanger for better thermo-hydraulic performance analysis without the need of time consuming and expensive experimentation.
High-Performance Computing Paradigm and Infrastructure
Yang, Laurence T
2006-01-01
With hyperthreading in Intel processors, hypertransport links in next generation AMD processors, multi-core silicon in today's high-end microprocessors from IBM and emerging grid computing, parallel and distributed computers have moved into the mainstream
Directory of Open Access Journals (Sweden)
Müller Jonas
2015-01-01
Full Text Available Mixing processes for modern wine-making occur repeatedly during fermentation (e.g. yeast addition, wine fermen- tation additives, as well as after fermentation (e.g. blending, dosage, sulfur additions. In large fermentation vessels or when mixing fluids of different viscosities, an inadequate mixing process can lead to considerable costs and problems (inhomogeneous product, development of layers in the tank, waste of energy, clogging of filters. Considering advancements in computational fluid dynamics (CFD in the last few years and the computational power of computers nowadays, most large-scale wineries would be able to conduct mixing simulations using their own tank and agitator configurations in order to evaluate their efficiency and the necessary power input based on mathematical modeling. Regardless, most companies still rely on estimations and empirical values which are neither validated nor optimized. The free open-source CFD software OpenFOAM (v.2.3.1 is used to simulate flows in wine tanks. Different agitator types, different propeller geometries and rotational speeds can be modeled and compared amongst each other in the process. Moreover, fluid properties of different wine additives can be modeled. During opti- cal post-processing using the open-source software ParaView (v.4.3 the progression of homogenization can be visualized and poorly mixed regions in the tank are revealed.
Energy Technology Data Exchange (ETDEWEB)
Jardini, Andre L.; Bineli, Aulus R.R.; Viadana, Adriana M.; Maciel, Maria Regina Wolf; Maciel Filho, Rubens [State University of Campinas (UNICAMP), SP (Brazil). School of Chemical Engineering; Medina, Lilian C.; Gomes, Alexandre de O. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Barros, Ricardo S. [University Foundation Jose Bonifacio (FUJB), Rio de Janeiro, RJ (Brazil)
2008-07-01
In this paper, the design of microreactor with microfluidics channels has been carried out in Computer Aided Design Software (CAD) and constructed in rapid prototyping system to be used in chemical reaction processing of the heavy oil fractions. The flow pattern properties of microreactor (fluid dynamics, mixing behavior) have been considered through CFD (computational fluid dynamics) simulations. CFD calculations are also used to study the design and specification of new microreactor developments. The potential advantages of using a microreactor include better control of reaction conditions, improved safety and portability. A more detailed crude assay of the raw national oil, whose importance was evidenced by PETROBRAS/CENPES allows establishing the optimum strategies and processing conditions, aiming at a maximum utilization of the heavy oil fractions, towards valuable products. These residues are able to be processed in microreactor, in which conventional process like as hydrotreating, catalytic and thermal cracking may be carried out in a much more intensified fashion. The whole process development involves a prior thermal study to define the possible operating conditions for a particular task, the microreactor design through computational fluid dynamics and construction using rapid prototyping. This gives high flexibility for process development, shorter time, and costumer/task oriented process/product development. (author)
Thermodynamic and transport properties of nitrogen fluid: Molecular theory and computer simulations
Eskandari Nasrabad, A.; Laghaei, R.
2018-04-01
Computer simulations and various theories are applied to compute the thermodynamic and transport properties of nitrogen fluid. To model the nitrogen interaction, an existing potential in the literature is modified to obtain a close agreement between the simulation results and experimental data for the orthobaric densities. We use the Generic van der Waals theory to calculate the mean free volume and apply the results within the modified Cohen-Turnbull relation to obtain the self-diffusion coefficient. Compared to experimental data, excellent results are obtained via computer simulations for the orthobaric densities, the vapor pressure, the equation of state, and the shear viscosity. We analyze the results of the theory and computer simulations for the various thermophysical properties.
VISUALIZATION METHODS OF VORTICAL FLOWS IN COMPUTATIONAL FLUID DYNAMICS AND THEIR APPLICATIONS
Directory of Open Access Journals (Sweden)
K. N. Volkov
2014-05-01
Full Text Available The paper deals with conceptions and methods for visual representation of research numerical results in the problems of fluid mechanics and gas. The three-dimensional nature of unsteady flow being simulated creates significant difficulties for the visual representation of results. It complicates control and understanding of numerical data, and exchange and processing of obtained information about the flow field. Approaches to vortical flows visualization with the usage of gradients of primary and secondary scalar and vector fields are discussed. An overview of visualization techniques for vortical flows using different definitions of the vortex and its identification criteria is given. Visualization examples for some solutions of gas dynamics problems related to calculations of jets and cavity flows are presented. Ideas of the vortical structure of the free non-isothermal jet and the formation of coherent vortex structures in the mixing layer are developed. Analysis of formation patterns for spatial flows inside large-scale vortical structures within the enclosed space of the cubic lid-driven cavity is performed. The singular points of the vortex flow in a cubic lid-driven cavity are found based on the results of numerical simulation; their type and location are identified depending on the Reynolds number. Calculations are performed with fine meshes and modern approaches to the simulation of vortical flows (direct numerical simulation and large-eddy simulation. Paradigm of graphical programming and COVISE virtual environment are used for the visual representation of computational results. Application that implements the visualization of the problem is represented as a network which links are modules and each of them is designed to solve a case-specific problem. Interaction between modules is carried out by the input and output ports (data receipt and data transfer giving the possibility to use various input and output devices.
Nielsen, Tanner; West, Jeff
2015-01-01
The Scale Model Acoustic Test (SMAT) is a 5% scale test of the Space Launch System (SLS), which is currently being designed at Marshall Space Flight Center (MSFC). The purpose of this test is to characterize and understand a variety of acoustic phenomena that occur during the early portions of lift off, one being the overpressure environment that develops shortly after booster ignition. The pressure waves that propagate from the mobile launcher (ML) exhaust hole are defined as the ignition overpressure (IOP), while the portion of the pressure waves that exit the duct or trench are the duct overpressure (DOP). Distinguishing the IOP and DOP in scale model test data has been difficult in past experiences and in early SMAT results, due to the effects of scaling the geometry. The speed of sound of the air and combustion gas constituents is not scaled, and therefore the SMAT pressure waves propagate at approximately the same speed as occurs in full scale. However, the SMAT geometry is twenty times smaller, allowing the pressure waves to move down the exhaust hole, through the trench and duct, and impact the vehicle model much faster than occurs at full scale. The DOP waves impact portions of the vehicle at the same time as the IOP waves, making it difficult to distinguish the different waves and fully understand the data. To better understand the SMAT data, a computational fluid dynamics (CFD) analysis was performed with a fictitious geometry that isolates the IOP and DOP. The upper and lower portions of the domain were segregated to accomplish the isolation in such a way that the flow physics were not significantly altered. The Loci/CHEM CFD software program was used to perform this analysis.
Energy Technology Data Exchange (ETDEWEB)
Scheuerer, Martina, E-mail: Martina.Scheuerer@grs.de [Gesellschaft fuer Anlagen- und Reaktorsicherheit, Forschungsinstitute, 85748 Garching (Germany); Weis, Johannes, E-mail: Johannes.Weis@grs.de [Gesellschaft fuer Anlagen- und Reaktorsicherheit, Forschungsinstitute, 85748 Garching (Germany)
2012-12-15
Highlights: Black-Right-Pointing-Pointer Pressurized thermal shocks are important phenomena for plant life extension and aging. Black-Right-Pointing-Pointer The thermal-hydraulics of PTS have been studied experimentally and numerically. Black-Right-Pointing-Pointer In the Large Scale Test Facility a loss of coolant accident was investigated. Black-Right-Pointing-Pointer CFD software is validated to simulate the buoyancy driven flow after ECC injection. - Abstract: Within the framework of the European Nuclear Reactor Integrated Simulation Project (NURISP), computational fluid dynamics (CFD) software is validated for the simulation of the thermo-hydraulics of pressurized thermal shocks. A proposed validation experiment is the test series performed within the OECD ROSA V project in the Large Scale Test Facility (LSTF). The LSTF is a 1:48 volume-scaled model of a four-loop Westinghouse pressurized water reactor (PWR). ROSA V Test 1-1 investigates temperature stratification under natural circulation conditions. This paper describes calculations which were performed with the ANSYS CFD software for emergency core cooling injection into one loop at single-phase flow conditions. Following the OECD/NEA CFD Best Practice Guidelines (Mahaffy, 2007) the influence of grid resolution, discretisation schemes, and turbulence models (shear stress transport and Reynolds stress model) on the mixing in the cold leg were investigated. A half-model was used for these simulations. The transient calculations were started from a steady-state solution at natural circulation conditions. The final calculations were obtained in a complete model of the downcomer. The results are in good agreement with data.
International Nuclear Information System (INIS)
Scheuerer, Martina; Weis, Johannes
2012-01-01
Highlights: ► Pressurized thermal shocks are important phenomena for plant life extension and aging. ► The thermal-hydraulics of PTS have been studied experimentally and numerically. ► In the Large Scale Test Facility a loss of coolant accident was investigated. ► CFD software is validated to simulate the buoyancy driven flow after ECC injection. - Abstract: Within the framework of the European Nuclear Reactor Integrated Simulation Project (NURISP), computational fluid dynamics (CFD) software is validated for the simulation of the thermo-hydraulics of pressurized thermal shocks. A proposed validation experiment is the test series performed within the OECD ROSA V project in the Large Scale Test Facility (LSTF). The LSTF is a 1:48 volume-scaled model of a four-loop Westinghouse pressurized water reactor (PWR). ROSA V Test 1-1 investigates temperature stratification under natural circulation conditions. This paper describes calculations which were performed with the ANSYS CFD software for emergency core cooling injection into one loop at single-phase flow conditions. Following the OECD/NEA CFD Best Practice Guidelines (Mahaffy, 2007) the influence of grid resolution, discretisation schemes, and turbulence models (shear stress transport and Reynolds stress model) on the mixing in the cold leg were investigated. A half-model was used for these simulations. The transient calculations were started from a steady-state solution at natural circulation conditions. The final calculations were obtained in a complete model of the downcomer. The results are in good agreement with data.
Jäger, Willi
2000-01-01
The book contains reports about the most significant projects from science and engineering of the Federal High Performance Computing Center Stuttgart (HLRS). They were carefully selected in a peer-review process and are showcases of an innovative combination of state-of-the-art modeling, novel algorithms and the use of leading-edge parallel computer technology. The projects of HLRS are using supercomputer systems operated jointly by university and industry and therefore a special emphasis has been put on the industrial relevance of results and methods.
Jäger, Willi
1999-01-01
The book contains reports about the most significant projects from science and industry that are using the supercomputers of the Federal High Performance Computing Center Stuttgart (HLRS). These projects are from different scientific disciplines, with a focus on engineering, physics and chemistry. They were carefully selected in a peer-review process and are showcases for an innovative combination of state-of-the-art physical modeling, novel algorithms and the use of leading-edge parallel computer technology. As HLRS is in close cooperation with industrial companies, special emphasis has been put on the industrial relevance of results and methods.
Moving finite elements: A continuously adaptive method for computational fluid dynamics
International Nuclear Information System (INIS)
Glasser, A.H.; Miller, K.; Carlson, N.
1991-01-01
Moving Finite Elements (MFE), a recently developed method for computational fluid dynamics, promises major advances in the ability of computers to model the complex behavior of liquids, gases, and plasmas. Applications of computational fluid dynamics occur in a wide range of scientifically and technologically important fields. Examples include meteorology, oceanography, global climate modeling, magnetic and inertial fusion energy research, semiconductor fabrication, biophysics, automobile and aircraft design, industrial fluid processing, chemical engineering, and combustion research. The improvements made possible by the new method could thus have substantial economic impact. Moving Finite Elements is a moving node adaptive grid method which has a tendency to pack the grid finely in regions where it is most needed at each time and to leave it coarse elsewhere. It does so in a manner which is simple and automatic, and does not require a large amount of human ingenuity to apply it to each particular problem. At the same time, it often allows the time step to be large enough to advance a moving shock by many shock thicknesses in a single time step, moving the grid smoothly with the solution and minimizing the number of time steps required for the whole problem. For 2D problems (two spatial variables) the grid is composed of irregularly shaped and irregularly connected triangles which are very flexible in their ability to adapt to the evolving solution. While other adaptive grid methods have been developed which share some of these desirable properties, this is the only method which combines them all. In many cases, the method can save orders of magnitude of computing time, equivalent to several generations of advancing computer hardware
International Nuclear Information System (INIS)
Hu, Q; Li, Y; Pan, H L; Liu, J T; Zhuang, B T
2015-01-01
Vane type propellant management device (PMD) is one of the key components of the vane-type surface tension tank (STT), and its fluid orbital performance directly determines the STT's success or failure. In present paper, numerical analysis and microgravity experiment study on fluid orbital performance of a vane type PMD were carried out. By using two-phase flow model of volume of fluid (VOF), fluid flow characteristics in the tank with the vane type PMD were numerically calculated, and the rules of fluid transfer and distribution were gotten. A abbreviate model test system of the vane type PMD is established and microgravity drop tower tests were performed, then fluid management and transmission rules of the vane type PMD were obtained under microgravity environment. The analysis and tests results show that the vane type PMD has good and initiative fluid orbital management ability and meets the demands of fluid orbital extrusion in the vane type STT. The results offer valuable guidance for the design and optimization of the new generation of vane type PMD, and also provide a new approach for fluid management and control in space environment
VHBORE: A code to compute borehole fluid conductivity profiles with pressure changes in the borehole
International Nuclear Information System (INIS)
Hale, F.V.; Tsang, C.F.
1994-06-01
This report describes the code VHBORE which can be used to model fluid electric conductivity profiles in a borehole intersecting fractured rock under conditions of changing pressure in the well bore. Pressure changes may be due to water level variations caused by pumping or fluid density effects as formation fluid is drawn into the borehole. Previous reports describe the method of estimating the hydrologic behavior of fractured rock using a time series of electric conductivity logs and an earlier code, BORE, to generate electric conductivity logs under constant pressure and flow rate conditions. The earlier model, BORE, assumed a constant flow rate, q i , for each inflow into the well bore. In the present code the user supplies the location, constant pressure, h i , transmissivity, T i , and storativity, S i , for each fracture, as well as the initial water level in the well, h w (0), In addition, the input data contains changes in the water level at later times, Δh w (t), typically caused by turning a pump on or off. The variable density calculation also requires input of the density of each of the inflow fluids, ρ i , and the initial uniform density of the well bore fluid, ρ w (0). These parameters are used to compute the flow rate for each inflow point at each time step. The numerical method of Jacob and Lohman (1952) is used to compute the flow rate into or out of the fractures based on the changes in pressure in the wellbore. A dimensionless function relates flow rate as a function of time in response to an imposed pressure change. The principle of superposition is used to determine the net flow rate from a time series of pressure changes. Additional reading on the relationship between drawdown and flow rate can be found in Earlougher (1977), particularly his Section 4.6, open-quotes Constant-Pressure Flow Testingclose quotes
High-performance computing for structural mechanics and earthquake/tsunami engineering
Hori, Muneo; Ohsaki, Makoto
2016-01-01
Huge earthquakes and tsunamis have caused serious damage to important structures such as civil infrastructure elements, buildings and power plants around the globe. To quantitatively evaluate such damage processes and to design effective prevention and mitigation measures, the latest high-performance computational mechanics technologies, which include telascale to petascale computers, can offer powerful tools. The phenomena covered in this book include seismic wave propagation in the crust and soil, seismic response of infrastructure elements such as tunnels considering soil-structure interactions, seismic response of high-rise buildings, seismic response of nuclear power plants, tsunami run-up over coastal towns and tsunami inundation considering fluid-structure interactions. The book provides all necessary information for addressing these phenomena, ranging from the fundamentals of high-performance computing for finite element methods, key algorithms of accurate dynamic structural analysis, fluid flows ...
Computational Fluid Dynamics (CFD) Analysis for the Reduction of Impeller Discharge Flow Distortion
Garcia, R.; McConnaughey, P. K.; Eastland, A.
1993-01-01
The use of Computational Fluid Dynamics (CFD) in the design and analysis of high performance rocket engine pumps has increased in recent years. This increase has been aided by the activities of the Marshall Space Flight Center (MSFC) Pump Stage Technology Team (PSTT). The team's goals include assessing the accuracy and efficiency of several methodologies and then applying the appropriate methodology(s) to understand and improve the flow inside a pump. The PSTT's objectives, team membership, and past activities are discussed in Garcia1 and Garcia2. The PSTT is one of three teams that form the NASA/MSFC CFD Consortium for Applications in Propulsion Technology (McConnaughey3). The PSTT first applied CFD in the design of the baseline consortium impeller. This impeller was designed for the Space Transportation Main Engine's (STME) fuel turbopump. The STME fuel pump was designed with three impeller stages because a two-stage design was deemed to pose a high developmental risk. The PSTT used CFD to design an impeller whose performance allowed for a two-stage STME fuel pump design. The availability of this design would have lead to a reduction in parts, weight, and cost had the STME reached production. One sample of the baseline consortium impeller was manufactured and tested in a water rig. The test data showed that the impeller performance was as predicted and that a two-stage design for the STME fuel pump was possible with minimal risk. The test data also verified another CFD predicted characteristic of the design that was not desirable. The classical 'jet-wake' pattern at the impeller discharge was strengthened by two aspects of the design: by the high head coefficient necessary for the required pressure rise and by the relatively few impeller exit blades, 12, necessary to reduce manufacturing cost. This 'jet-wake pattern produces an unsteady loading on the diffuser vanes and has, in past rocket engine programs, lead to diffuser structural failure. In industrial
Energy Technology Data Exchange (ETDEWEB)
Kristoffersen, Astrid R.; Hannisdal, Andreas; Amarzguioui, Morad; Wood, Deborah; Tor Andersen [Aibel, Stavanger (Norway)
2008-07-01
To have the necessary confidence in a separators' performance, the design must be based on more than simple design rules. A combination of separation testing, computer modelling, and general knowledge of the process is needed. In addition, new technologies can provide enhanced overall performance when it is required. This paper describes how all of these techniques can be combined to get the most out of separator design. We will describe how Aibel has used Computational Fluid Dynamics (CFD), together with laboratory testing, multi-disciplinary knowledge and new technology in order to revolutionize the way we design separators. This paper will present a study of separation performance for one of our customers. A CFD simulation was performed to predict the internal waves inside a separator located on a FPSO, and how these affect separation phenomena. The performance of the theoretical CFD model was verified by laboratory wave experiments. Separation tests were performed to test new solutions which could increase the performance of the process. Based on the CFD simulations and the separation tests, a modification of the separator was proposed. (author)
International Nuclear Information System (INIS)
Amirante, R.; Moscatelli, P.G.; Catalano, L.A.
2007-01-01
The aim of this paper is to investigate the fluid dynamic behaviour of a commercial hydraulic proportional valve in order to evaluate and justify its global performances and, in particular, to analyze the effects of some additional design features on the reduction of the force required to maintain the valve open. The proposed analysis has been performed by applying the commercial computational fluid dynamics (CFD) code, Fluent, to the solution of the three dimensional turbulent flow field through a circumferential sector of the entire valve for different spool strokes. The reliability of the employed modelization is demonstrated by the comparison between the computed flow rate curve and the corresponding experimental data provided by the manufacturer. With regard to the metering edge design, it is shown that the cylindrical hole provided on the top of the hemi-spherical notch to improve metering at small valve openings has no influence on the flow force balance. The presented results also demonstrate that compensation techniques based on an adequate spool profiling are effective in balancing the flow forces mainly at medium and large valve openings, thanks to the pressure difference on the compensation profile; which also results in an increased axial momentum at the inlet of the high pressure chamber. The benefits of its presence are amplified by the adoption of two grooves machined on the valve body, which modify the flow field so as both to increase the axial momentum at the inlet of the high pressure chamber and to reduce it at the outlet
Computational Fluid Dynamics (CFD) Simulations of Jet Mixing in Tanks of Different Scales
Breisacher, Kevin; Moder, Jeffrey
2010-01-01
For long-duration in-space storage of cryogenic propellants, an axial jet mixer is one concept for controlling tank pressure and reducing thermal stratification. Extensive ground-test data from the 1960s to the present exist for tank diameters of 10 ft or less. The design of axial jet mixers for tanks on the order of 30 ft diameter, such as those planned for the Ares V Earth Departure Stage (EDS) LH2 tank, will require scaling of available experimental data from much smaller tanks, as well designing for microgravity effects. This study will assess the ability for Computational Fluid Dynamics (CFD) to handle a change of scale of this magnitude by performing simulations of existing ground-based axial jet mixing experiments at two tank sizes differing by a factor of ten. Simulations of several axial jet configurations for an Ares V scale EDS LH2 tank during low Earth orbit (LEO) coast are evaluated and selected results are also presented. Data from jet mixing experiments performed in the 1960s by General Dynamics with water at two tank sizes (1 and 10 ft diameter) are used to evaluate CFD accuracy. Jet nozzle diameters ranged from 0.032 to 0.25 in. for the 1 ft diameter tank experiments and from 0.625 to 0.875 in. for the 10 ft diameter tank experiments. Thermally stratified layers were created in both tanks prior to turning on the jet mixer. Jet mixer efficiency was determined by monitoring the temperatures on thermocouple rakes in the tanks to time when the stratified layer was mixed out. Dye was frequently injected into the stratified tank and its penetration recorded. There were no velocities or turbulence quantities available in the experimental data. A commercially available, time accurate, multi-dimensional CFD code with free surface tracking (FLOW-3D from Flow Science, Inc.) is used for the simulations presented. Comparisons are made between computed temperatures at various axial locations in the tank at different times and those observed experimentally. The
Energy Technology Data Exchange (ETDEWEB)
Lundquist, J K; Chan, S T
2005-11-30
The validity of omitting stability considerations when simulating transport and dispersion in the urban environment is explored using observations from the Joint URBAN 2003 field experiment and computational fluid dynamics simulations of that experiment. Four releases of sulfur hexafluoride, during two daytime and two nighttime intensive observing periods, are simulated using the building-resolving computational fluid dynamics model, FEM3MP to solve the Reynolds Averaged Navier-Stokes equations with two options of turbulence parameterizations. One option omits stability effects but has a superior turbulence parameterization using a non-linear eddy viscosity (NEV) approach, while the other considers buoyancy effects with a simple linear eddy viscosity (LEV) approach for turbulence parameterization. Model performance metrics are calculated by comparison with observed winds and tracer data in the downtown area, and with observed winds and turbulence kinetic energy (TKE) profiles at a location immediately downwind of the central business district (CBD) in the area we label as the urban shadow. Model predictions of winds, concentrations, profiles of wind speed, wind direction, and friction velocity are generally consistent with and compare reasonably well with the field observations. Simulations using the NEV turbulence parameterization generally exhibit better agreement with observations. To further explore this assumption of a neutrally-stable atmosphere within the urban area, TKE budget profiles slightly downwind of the urban wake region in the 'urban shadow' are examined. Dissipation and shear production are the largest terms which may be calculated directly. The advection of TKE is calculated as a residual; as would be expected downwind of an urban area, the advection of TKE produced within the urban area is a very large term. Buoyancy effects may be neglected in favor of advection, shear production, and dissipation. For three of the IOPs, buoyancy
Fluid history computation methods for reactor safeguards problems using MNODE computer program
International Nuclear Information System (INIS)
Huang, Y.S.; Savery, C.W.
1976-10-01
A method for predicting the pressure-temperature histories of air, water liquid, and vapor flowing in a zoned containment as a result of high energy pipe rupture is described. The computer code, MNODE, has been developed for 12 connected control volumes and 24 inertia flow paths. Predictions by the code are compared with the results of an analytical gas dynamic problem, semiscale blowdown experiments, full scale MARVIKEN test results, Battelle-Frankfurt model PWR containment test data. The MNODE solutions to NRC/AEC subcompartment benchmark problems are also compared with results predicted by other computer codes such as RELAP-3, FLASH-2, CONTEMPT-PS. The analytical consideration is consistent with Section 6.2.1.2 of the Standard Format (Rev. 2) issued by U.S. Nuclear Regulatory Commission in September 1975
Partridge, P; Boundary Elements in Fluid Dynamics
1992-01-01
This book Boundary Elements in Fluid Dynamics is the second volume of the two volume proceedings of the International Conference on Computer Modelling of Seas and Coastal Regions and Boundary Elements and Fluid Dynamics, held in Southampton, U.K., in April 1992. The Boundary Element Method (BEM) is now fully established as an ac curate and successful technique for solving engineering problems in a wide range of fields. The success of the method is due to its advantages in data reduction, as only the boundary of the region is modelled. Thus moving boundaries may be more easily handled, which is not the case if domain methods are used. In addition, the method is easily able to model regions to extending to infinity. Fluid mechanics is traditionally one of the most challenging areas of engi neering, the simulation of fluid motion, particularly in three dimensions, is always a serious test for any numerical method, and is an area in which BEM analysis may be used taking full advantage of its special character...
Computational multi-fluid dynamics predictions of critical heat flux in boiling flow
International Nuclear Information System (INIS)
Mimouni, S.; Baudry, C.; Guingo, M.; Lavieville, J.; Merigoux, N.; Mechitoua, N.
2016-01-01
Highlights: • A new mechanistic model dedicated to DNB has been implemented in the Neptune_CFD code. • The model has been validated against 150 tests. • Neptune_CFD code is a CFD tool dedicated to boiling flows. - Abstract: Extensive efforts have been made in the last five decades to evaluate the boiling heat transfer coefficient and the critical heat flux in particular. Boiling crisis remains a major limiting phenomenon for the analysis of operation and safety of both nuclear reactors and conventional thermal power systems. As a consequence, models dedicated to boiling flows have being improved. For example, Reynolds Stress Transport Model, polydispersion and two-phase flow wall law have been recently implemented. In a previous work, we have evaluated computational fluid dynamics results against single-phase liquid water tests equipped with a mixing vane and against two-phase boiling cases. The objective of this paper is to propose a new mechanistic model in a computational multi-fluid dynamics tool leading to wall temperature excursion and onset of boiling crisis. Critical heat flux is calculated against 150 tests and the mean relative error between calculations and experimental values is equal to 8.3%. The model tested covers a large physics scope in terms of mass flux, pressure, quality and channel diameter. Water and R12 refrigerant fluid are considered. Furthermore, it was found that the sensitivity to the grid refinement was acceptable.
Computational multi-fluid dynamics predictions of critical heat flux in boiling flow
Energy Technology Data Exchange (ETDEWEB)
Mimouni, S., E-mail: stephane.mimouni@edf.fr; Baudry, C.; Guingo, M.; Lavieville, J.; Merigoux, N.; Mechitoua, N.
2016-04-01
Highlights: • A new mechanistic model dedicated to DNB has been implemented in the Neptune-CFD code. • The model has been validated against 150 tests. • Neptune-CFD code is a CFD tool dedicated to boiling flows. - Abstract: Extensive efforts have been made in the last five decades to evaluate the boiling heat transfer coefficient and the critical heat flux in particular. Boiling crisis remains a major limiting phenomenon for the analysis of operation and safety of both nuclear reactors and conventional thermal power systems. As a consequence, models dedicated to boiling flows have being improved. For example, Reynolds Stress Transport Model, polydispersion and two-phase flow wall law have been recently implemented. In a previous work, we have evaluated computational fluid dynamics results against single-phase liquid water tests equipped with a mixing vane and against two-phase boiling cases. The objective of this paper is to propose a new mechanistic model in a computational multi-fluid dynamics tool leading to wall temperature excursion and onset of boiling crisis. Critical heat flux is calculated against 150 tests and the mean relative error between calculations and experimental values is equal to 8.3%. The model tested covers a large physics scope in terms of mass flux, pressure, quality and channel diameter. Water and R12 refrigerant fluid are considered. Furthermore, it was found that the sensitivity to the grid refinement was acceptable.
Birmingham, E; Grogan, J A; Niebur, G L; McNamara, L M; McHugh, P E
2013-04-01
Bone marrow found within the porous structure of trabecular bone provides a specialized environment for numerous cell types, including mesenchymal stem cells (MSCs). Studies have sought to characterize the mechanical environment imposed on MSCs, however, a particular challenge is that marrow displays the characteristics of a fluid, while surrounded by bone that is subject to deformation, and previous experimental and computational studies have been unable to fully capture the resulting complex mechanical environment. The objective of this study was to develop a fluid structure interaction (FSI) model of trabecular bone and marrow to predict the mechanical environment of MSCs in vivo and to examine how this environment changes during osteoporosis. An idealized repeating unit was used to compare FSI techniques to a computational fluid dynamics only approach. These techniques were used to determine the effect of lower bone mass and different marrow viscosities, representative of osteoporosis, on the shear stress generated within bone marrow. Results report that shear stresses generated within bone marrow under physiological loading conditions are within the range known to stimulate a mechanobiological response in MSCs in vitro. Additionally, lower bone mass leads to an increase in the shear stress generated within the marrow, while a decrease in bone marrow viscosity reduces this generated shear stress.
DOE research in utilization of high-performance computers
International Nuclear Information System (INIS)
Buzbee, B.L.; Worlton, W.J.; Michael, G.; Rodrigue, G.
1980-12-01
Department of Energy (DOE) and other Government research laboratories depend on high-performance computer systems to accomplish their programatic goals. As the most powerful computer systems become available, they are acquired by these laboratories so that advances can be made in their disciplines. These advances are often the result of added sophistication to numerical models whose execution is made possible by high-performance computer systems. However, high-performance computer systems have become increasingly complex; consequently, it has become increasingly difficult to realize their potential performance. The result is a need for research on issues related to the utilization of these systems. This report gives a brief description of high-performance computers, and then addresses the use of and future needs for high-performance computers within DOE, the growing complexity of applications within DOE, and areas of high-performance computer systems warranting research. 1 figure
Fluid-Induced Vibration Analysis for Reactor Internals Using Computational FSI Method
Energy Technology Data Exchange (ETDEWEB)
Moon, Jong Sung; Yi, Kun Woo; Sung, Ki Kwang; Im, In Young; Choi, Taek Sang [KEPCO E and C, Daejeon (Korea, Republic of)
2013-10-15
This paper introduces a fluid-induced vibration analysis method which calculates the response of the RVI to both deterministic and random loads at once and utilizes more realistic pressure distribution using the computational Fluid Structure Interaction (FSI) method. As addressed above, the FIV analysis for the RVI was carried out using the computational FSI method. This method calculates the response to deterministic and random turbulence loads at once. This method is also a simple and integrative method to get structural dynamic responses of reactor internals to various flow-induced loads. Because the analysis of this paper omitted the bypass flow region and Inner Barrel Assembly (IBA) due to the limitation of computer resources, it is necessary to find an effective way to consider all regions in the RV for the FIV analysis in the future. Reactor coolant flow makes Reactor Vessel Internals (RVI) vibrate and may affect the structural integrity of them. U. S. NRC Regulatory Guide 1.20 requires the Comprehensive Vibration Assessment Program (CVAP) to verify the structural integrity of the RVI for Fluid-Induced Vibration (FIV). The hydraulic forces on the RVI of OPR1000 and APR1400 were computed from the hydraulic formulas and the CVAP measurements in Palo Verde Unit 1 and Yonggwang Unit 4 for the structural vibration analyses. In this method, the hydraulic forces were divided into deterministic and random turbulence loads and were used for the excitation forces of the separate structural analyses. These forces are applied to the finite element model and the responses to them were combined into the resultant stresses.
Studies on variable swirl intake system for DI diesel engine using computational fluid dynamics
Directory of Open Access Journals (Sweden)
Jebamani Rathnaraj David
2008-01-01
Full Text Available It is known that a helical port is more effective than a tangential port to attain the required swirl ratio with minimum sacrifice in the volumetric efficiency. The swirl port is designed for lesser swirl ratio to reduce emissions at higher speeds. But this condition increases the air fuel mixing time and particulate smoke emissions at lower speeds. Optimum swirl ratio is necessary according to the engine operating condition for optimum combustion and emission reduction. Hence the engine needs variable swirl to enhance the combustion in the cylinder according to its operating conditions, for example at partial load or low speed condition it requires stronger swirl, while the air quantity is more important than the swirl under very high speed or full load and maximum torque conditions. The swirl and charging quantity can easily trade off and can be controlled by the opening of the valve. Hence in this study the steady flow rig experiment is used to evaluate the swirl of a helical intake port design for different operating conditions. The variable swirl plate set up of the W06DTIE2 engine is used to experimentally study the swirl variation for different openings of the valve. The sliding of the swirl plate results in the variation of the area of inlet port entry. Therefore in this study a swirl optimized combustion system varying according to the operating conditions by a variable swirl plate mechanism is studied experimentally and compared with the computational fluid dynamics predictions. In this study the fluent computational fluid dynamics code has been used to evaluate the flow in the port-cylinder system of a DI diesel engine in a steady flow rig. The computational grid is generated directly from 3-D CAD data and in cylinder flow simulations, with inflow boundary conditions from experimental measurements, are made using the fluent computational fluid dynamics code. The results are in very good agreement with experimental results.
Parallel computing simulation of fluid flow in the unsaturated zone of Yucca Mountain, Nevada
International Nuclear Information System (INIS)
Zhang, Keni; Wu, Yu-Shu; Bodvarsson, G.S.
2001-01-01
This paper presents the application of parallel computing techniques to large-scale modeling of fluid flow in the unsaturated zone (UZ) at Yucca Mountain, Nevada. In this study, parallel computing techniques, as implemented into the TOUGH2 code, are applied in large-scale numerical simulations on a distributed-memory parallel computer. The modeling study has been conducted using an over-one-million-cell three-dimensional numerical model, which incorporates a wide variety of field data for the highly heterogeneous fractured formation at Yucca Mountain. The objective of this study is to analyze the impact of various surface infiltration scenarios (under current and possible future climates) on flow through the UZ system, using various hydrogeological conceptual models with refined grids. The results indicate that the one-million-cell models produce better resolution results and reveal some flow patterns that cannot be obtained using coarse-grid modeling models
Directory of Open Access Journals (Sweden)
Ling Jacky
2018-01-01
Full Text Available Biofouling is the accumulation of unwanted material on surfaces submerged or semi submerged over an extended period. This study investigates the antifouling performance of a new bioinspired topography design. A shark riblets inspired topography was designed with Solidworks and CFD simulations were antifouling performance. The study focuses on the fluid flow velocity, the wall shear stress and the appearance of vortices are to be noted to determine the possible locations biofouling would most probably occur. The inlet mass flow rate is 0.01 kgs-1 and a no-slip boundary condition was applied to the walls of the fluid domain. Simulations indicate that Velocity around the topography averaged at 7.213 x 10-3 ms-1. However, vortices were observed between the gaps. High wall shear stress is observed at the peak of each topography. In contrast, wall shear stress is significantly low at the bed of the topography. This suggests the potential location for the accumulation of biofouling. Results show that bioinspired antifouling topography can be improved by reducing the frequency of gaps between features. Linear surfaces on the topography should also be minimized. This increases the avenues of flow for the fluid, thus potentially increasing shear stresses with surrounding fluid leading to better antifouling performance.
International Nuclear Information System (INIS)
Chen, Jiaoliao; Xu, Fang; Tan, Dapeng; Shen, Zheng; Zhang, Libin; Ai, Qinglin
2015-01-01
Highlights: • A novel control method for the heating greenhouse with SWSHPS is proposed. • CFD is employed to predict the priorities of FCU loops for thermal performance. • EPM is act as an on-line tool to predict the total energy demand of greenhouse. • The CFD–EPM-based method can save energy and improve control accuracy. • The energy savings potential is between 8.7% and 15.1%. - Abstract: As energy heating is one of the main production costs, many efforts have been made to reduce the energy consumption of agricultural greenhouses. Herein, a novel control method of greenhouse heating using computational fluid dynamics (CFD) and energy prediction model (EPM) is proposed for energy savings and system performance. Based on the low-Reynolds number k–ε turbulence principle, a CFD model of heating greenhouse is developed, applying the discrete ordinates model for the radiative heat transfers and porous medium approach for plants considering plants sensible and latent heat exchanges. The CFD simulations have been validated, and used to analyze the greenhouse thermal performance and the priority of fan coil units (FCU) loops under the various heating conditions. According to the heating efficiency and temperature uniformity, the priorities of each FCU loop can be predicted to generate a database with priorities for control system. EPM is built up based on the thermal balance, and used to predict and optimize the energy demand of the greenhouse online. Combined with the priorities of FCU loops from CFD simulations offline, we have developed the CFD–EPM-based heating control system of greenhouse with surface water source heat pumps system (SWSHPS). Compared with conventional multi-zone independent control (CMIC) method, the energy savings potential is between 8.7% and 15.1%, and the control temperature deviation is decreased to between 0.1 °C and 0.6 °C in the investigated greenhouse. These results show the CFD–EPM-based method can improve system
Kawamorita, Takushi; Shimizu, Kimiya; Shoji, Nobuyuki
2016-04-01
A modified implantable collamer lens (ICL) with a central hole with a diameter of 0.36 mm, referred to as a hole-ICL, was created to improve aqueous humour circulation. The aim of this study is to investigate the ideal hole size in a hole-ICL from the standpoint of the fluid dynamic characteristics of the aqueous humour using computational fluid dynamics. Fluid dynamics simulation using an ICL was performed with thermal-hydraulic analysis software FloEFD V 12.2 (Mentor Graphics Corp.). In the simulation, three-dimensional eye models based on a modified Liou-Brennan model eye with a conventional ICL (Model ICM, Staar Surgical) and a hole-ICL were used. The hole-ICL was -9.0 dioptres (D) and 12.0 mm in length, with an optic zone of 5.5 mm. The vaulting was 0.50 mm. The quantity of aqueous humour produced by the ciliary body was set at 2.80 μL/min. Flow distribution between the anterior surface of the crystalline lens and the posterior surface of the ICL was calculated, and trajectory analysis was performed. With an increase in the central hole size, the velocity of the aqueous humour increased, with the peak velocity occurring at a diameter of approximately 0.4 mm. Once the diameter had increased above 0.4 mm, the velocity then decreased. The velocity difference between the cases of a central hole size of 0.1 mm and 0.2 mm was significant. The desirable central hole size was 0.2 mm or larger in terms of flow dynamics. The current model, based on a central hole size of 0.36 mm, was close to ideal. The optimisation of the hole size should be performed based on results from a long-term clinical study so as to analyse the incidence rate of secondary cataract and optical performance.
Directory of Open Access Journals (Sweden)
Ding X. R.
2017-06-01
Full Text Available This study aims to design a novel air cleaning facility which conforms to the current situation in China, and moreover can satisfy our demand on air purification under the condition of poor air quality, as well as discuss the development means of a prototype product. Air conditions in the operating room of a hospital were measured as the research subject of this study. First, a suitable turbulence model and boundary conditions were selected and computational fluid dynamics (CFD software was used to simulate indoor air distribution. The analysis and comparison of the simulation results suggested that increasing the area of air supply outlets and the number of return air inlets would not only increase the area of unidirectional flow region in main flow region, but also avoid an indoor vortex and turbulivity of the operating area. Based on the summary of heat and humidity management methods, the system operation mode and relevant parameter technologies as well as the characteristics of the thermal-humidity load of the operating room were analyzed and compiled. According to the load value and parameters of indoor design obtained after our calculations, the airflow distribution of purifying the air-conditioning system in a clean operating room was designed and checked. The research results suggested that the application of a secondary return air system in the summer could reduce energy consumption and be consistent with the concept of primaiy humidity control. This study analyzed the feasibility and energy conservation properties of cleaning air-conditioning technology in operating rooms, proposed some solutions to the problem, and performed a feasible simulation, which provides a reference for practical engineering.
Computational Fluid Dynamics Study on the Effects of RATO Timing on the Scale Model Acoustic Test
Nielsen, Tanner; Williams, B.; West, Jeff
2015-01-01
The Scale Model Acoustic Test (SMAT) is a 5% scale test of the Space Launch System (SLS), which is currently being designed at Marshall Space Flight Center (MSFC). The purpose of this test is to characterize and understand a variety of acoustic phenomena that occur during the early portions of lift off, one being the overpressure environment that develops shortly after booster ignition. The SLS lift off configuration consists of four RS-25 liquid thrusters on the core stage, with two solid boosters connected to each side. Past experience with scale model testing at MSFC (in ER42), has shown that there is a delay in the ignition of the Rocket Assisted Take Off (RATO) motor, which is used as the 5% scale analog of the solid boosters, after the signal to ignite is given. This delay can range from 0 to 16.5ms. While this small of a delay maybe insignificant in the case of the full scale SLS, it can significantly alter the data obtained during the SMAT due to the much smaller geometry. The speed of sound of the air and combustion gas constituents is not scaled, and therefore the SMAT pressure waves propagate at approximately the same speed as occurs during full scale. However, the SMAT geometry is much smaller allowing the pressure waves to move down the exhaust duct, through the trench, and impact the vehicle model much faster than occurs at full scale. To better understand the effect of the RATO timing simultaneity on the SMAT IOP test data, a computational fluid dynamics (CFD) analysis was performed using the Loci/CHEM CFD software program. Five different timing offsets, based on RATO ignition delay statistics, were simulated. A variety of results and comparisons will be given, assessing the overall effect of RATO timing simultaneity on the SMAT overpressure environment.
Computational fluid dynamic analysis of core bypass flow phenomena in a prismatic VHTR
International Nuclear Information System (INIS)
Sato, Hiroyuki; Johnson, Richard; Schultz, Richard
2010-01-01
The core bypass flow in a prismatic very high temperature reactor (VHTR) is an important design consideration and can have considerable impact on the condition of reactor core internals including fuels. The interstitial gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The occurrence of hot spots in the core and lower plenum and hot streaking in the lower plenum (regions of very hot gas flow) are affected by bypass flow. In the present study, three-dimensional computational fluid dynamic (CFD) calculations of a typical prismatic VHTR are conducted to better understand bypass flow phenomena and establish an evaluation method for the reactor core using the commercial CFD code FLUENT. Parametric calculations changing several factors in a one-twelfth sector of a fuel column are performed. The simulations show the impact of each factor on bypass flow and the resulting flow and temperature distributions in the prismatic core. Factors include inter-column gap-width, turbulence model, axial heat generation profile and geometry change from irradiation-induced shrinkage in the graphite block region. It is shown that bypass flow provides a significant cooling effect on the prismatic block and that the maximum fuel and coolant channel outlet temperatures increase with an increase in gap-width, especially when a peak radial factor is applied to the total heat generation rate. Also, the presence of bypass flow causes a large lateral temperature gradient in the block and also dramatically increases the variation in coolant channel outlet temperatures for a given block that may have repercussions on the structural integrity of the graphite, the neutronics and the potential for hot streaking and hot spots occurring in the lower plenum.
Directory of Open Access Journals (Sweden)
Pinku Debnath
2017-03-01
Full Text Available Exergy losses during the combustion process, heat transfer, and fuel utilization play a vital role in the analysis of the exergetic efficiency of combustion process. Detonation is thermodynamically more efficient than deflagration mode of combustion. Detonation combustion technology inside the pulse detonation engine using hydrogen as a fuel is energetic propulsion system for next generation. In this study, the main objective of this work is to quantify the exergetic efficiency of hydrogen–air combustion for deflagration and detonation combustion process. Further detonation parameters are calculated using 0.25, 0.35, and 0.55 of H2 mass concentrations in the combustion process. The simulations have been performed for converging the solution using commercial computational fluid dynamics package Ansys Fluent solver. The details of combustion physics in chemical reacting flows of hydrogen–air mixture in two control volumes were simulated using species transport model with eddy dissipation turbulence chemistry interaction. From these simulations it was observed that exergy loss in the deflagration combustion process is higher in comparison to the detonation combustion process. The major observation was that pilot fuel economy for the two combustion processes and augmentation of exergetic efficiencies are better in the detonation combustion process. The maximum exergetic efficiency of 55.12%, 53.19%, and 23.43% from deflagration combustion process and from detonation combustion process, 67.55%, 57.49%, and 24.89%, are obtained from aforesaid H2 mass fraction. It was also found that for lesser fuel mass fraction higher exergetic efficiency was observed.
Energy Technology Data Exchange (ETDEWEB)
Xiao, Jianjun; Travis, Jack; Royl, Peter; Necker, Gottfried; Svishchev, Anatoly; Jordan, Thomas
2016-07-01
Karlsruhe Institute of Technology (KIT) is developing the parallel computational fluid dynamics code GASFLOW-MPI as a best-estimate tool for predicting transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containments and other facility buildings. GASFLOW-MPI is a finite-volume code based on proven computational fluid dynamics methodology that solves the compressible Navier-Stokes equations for three-dimensional volumes in Cartesian or cylindrical coordinates.
International Nuclear Information System (INIS)
Mavrou, Paschalia; Papadopoulos, Athanasios I.; Stijepovic, Mirko Z.; Seferlis, Panos; Linke, Patrick; Voutetakis, Spyros
2015-01-01
This work investigates the performance of working fluid mixtures for use in solar ORC (Organic Rankine Cycle systems) with heat storage employing FPC (Flat Plate Collectors). Several mixtures are considered including conventional choices often utilized in ORC as well as novel mixtures previously designed using advanced computer aided molecular design methods (Papadopoulos et al., 2013). The impact of heat source variability on the ORC performance is assessed for different working fluid mixtures. Solar radiation is represented in detail through actual, hourly averaged data for an entire year. A multi-criteria mixture selection methodology unveils important trade-offs among several important system operating parameters and efficiently highlights optimum operating ranges. Such parameters include the ORC thermal efficiency, the net generated power, the volume ratio across the turbine, the mass flow rate of the ORC working fluid, the evaporator temperature glide, the temperature drop in the storage tank, the ORC total yearly operating duration, the required collector aperture area to generate 1 kW of power and the irreversibility. A mixture of neopentane – 2-fluoromethoxy-2-methylpropane at 70% neopentane is found to be the most efficient in all the considered criteria simultaneously. - Highlights: • Investigation of novel and conventional working fluid mixtures for solar ORCs. • Systematic, multi-criteria assessment methodology for mixture selection. • Simultaneous consideration of multiple important mixture performance criteria. • Effects of year-round solar variability in a solar ORC with heat storage tank
National Research Council Canada - National Science Library
Jones, D
2003-01-01
..., spheres, flat plates, and wing profiles. The degree to which FIDAP accurately reproduces known experimental data on these shapes is described and the applicability of other Computational Fluid Dynamics packages is discussed. (13 tables, 2 figures, 38 refs.)