A Multiphase Model for the Intracluster Medium

Science.gov (United States)

Nagai, Daisuke; Sulkanen, Martin E.; Evrard, August E.

1999-01-01

Constraints on the clustered mass density of the universe derived from the observed population mean intracluster gas fraction of x-ray clusters may be biased by reliance on a single-phase assumption for the thermodynamic structure of the intracluster medium (ICM). We propose a descriptive model for multiphase structure in which a spherically symmetric ICM contains isobaric density perturbations with a radially dependent variance. Fixing the x-ray emission and emission weighted temperature, we explore two independently observable signatures of the model in the parameter space. For bremsstrahlung dominated emission, the central Sunyaev-Zel'dovich (SZ) decrement in the multiphase case is increased over the single-phase case and multiphase x-ray spectra in the range 0.1-20 keV are flatter in the continuum and exhibit stronger low energy emission lines than their single-phase counterpart. We quantify these effects for a fiducial 10e8 K cluster and demonstrate how the combination of SZ and x-ray spectroscopy can be used to identify a preferred location in the plane of the model parameter space. From these parameters the correct value of mean intracluster gas fraction in the multiphase model results, allowing an unbiased estimate of clustered mass density to he recovered.

Multi-physics modeling in electrical engineering. Application to a magneto-thermo-mechanical model

International Nuclear Information System (INIS)

Journeaux, Antoine

2013-01-01

The modeling of multi-physics problems in electrical engineering is presented, with an application to the numerical computation of vibrations within the end windings of large turbo-generators. This study is divided into four parts: the impositions of current density, the computation of local forces, the transfer of data between disconnected meshes, and the computation of multi-physics problems using weak coupling, Firstly, the representation of current density within numerical models is presented. The process is decomposed into two stages: the construction of the initial current density, and the determination of a divergence-free field. The representation of complex geometries makes the use of analytical methods impossible. A method based on an electrokinetic problem is used and a fully geometrical method are tested. The geometrical method produces results closer to the real current density than the electrokinetic problem. Methods to compute forces are numerous, and this study focuses on the virtual work principle and the Laplace force considering the recommendations of the literature. Laplace force is highly accurate but is applicable only if the permeability is uniform. The virtual work principle is finally preferred as it appears as the most general way to compute local forces. Mesh-to-mesh data transfer methods are developed to compute multi-physics models using multiples meshes adapted to the subproblems and multiple computational software. The interpolation method, a locally conservative projection, and an orthogonal projection are compared. Interpolation method is said to be fast but highly diffusive, and the orthogonal projections are highly accurate. The locally conservative method produces results similar to the orthogonal projection but avoid the assembly of linear systems. The numerical computation of multi-physical problems using multiple meshes and projections is then presented. However for a given class of problems, there is not an unique coupling

Multiphysics modelling of manufacturing processes: A review

DEFF Research Database (Denmark)

Jabbari, Masoud; Baran, Ismet; Mohanty, Sankhya

2018-01-01

Numerical modelling is increasingly supporting the analysis and optimization of manufacturing processes in the production industry. Even if being mostly applied to multistep processes, single process steps may be so complex by nature that the needed models to describe them must include multiphysics...... the diversity in the field of modelling of manufacturing processes as regards process, materials, generic disciplines as well as length scales: (1) modelling of tape casting for thin ceramic layers, (2) modelling the flow of polymers in extrusion, (3) modelling the deformation process of flexible stamps...... for nanoimprint lithography, (4) modelling manufacturing of composite parts and (5) modelling the selective laser melting process. For all five examples, the emphasis is on modelling results as well as describing the models in brief mathematical details. Alongside with relevant references to the original work...

Multiphase Microfluidics The Diffuse Interface Model

CERN Document Server

2012-01-01

Multiphase flows are typically described assuming that the different phases are separated by a sharp interface, with appropriate boundary conditions. This approach breaks down whenever the lengthscale of the phenomenon that is being studied is comparable with the real interface thickness, as it happens, for example, in the coalescence and breakup of bubbles and drops, the wetting and dewetting of solid surfaces and, in general, im micro-devices. The diffuse interface model resolves these probems by assuming that all quantities can vary continuously, so that interfaces have a non-zero thickness, i.e. they are "diffuse". The contributions in this book review the theory and describe some relevant applications of the diffuse interface model for one-component, two-phase fluids and for liquid binary mixtures, to model multiphase flows in confined geometries.

Continuum-Kinetic Models and Numerical Methods for Multiphase Applications

Science.gov (United States)

Nault, Isaac Michael

This thesis presents a continuum-kinetic approach for modeling general problems in multiphase solid mechanics. In this context, a continuum model refers to any model, typically on the macro-scale, in which continuous state variables are used to capture the most important physics: conservation of mass, momentum, and energy. A kinetic model refers to any model, typically on the meso-scale, which captures the statistical motion and evolution of microscopic entitites. Multiphase phenomena usually involve non-negligible micro or meso-scopic effects at the interfaces between phases. The approach developed in the thesis attempts to combine the computational performance benefits of a continuum model with the physical accuracy of a kinetic model when applied to a multiphase problem. The approach is applied to modeling a single particle impact in Cold Spray, an engineering process that intimately involves the interaction of crystal grains with high-magnitude elastic waves. Such a situation could be classified a multiphase application due to the discrete nature of grains on the spatial scale of the problem. For this application, a hyper elasto-plastic model is solved by a finite volume method with approximate Riemann solver. The results of this model are compared for two types of plastic closure: a phenomenological macro-scale constitutive law, and a physics-based meso-scale Crystal Plasticity model.

Multiphysics modelling of the spray forming process

International Nuclear Information System (INIS)

Mi, J.; Grant, P.S.; Fritsching, U.; Belkessam, O.; Garmendia, I.; Landaberea, A.

2008-01-01

An integrated, multiphysics numerical model has been developed through the joint efforts of the University of Oxford (UK), University of Bremen (Germany) and Inasmet (Spain) to simulate the spray forming process. The integrated model consisted of four sub-models: (1) an atomization model simulating the fragmentation of a continuous liquid metal stream into droplet spray during gas atomization; (2) a droplet spray model simulating the droplet spray mass and enthalpy evolution in the gas flow field prior to deposition; (3) a droplet deposition model simulating droplet deposition, splashing and re-deposition behavior and the resulting preform shape and heat flow; and (4) a porosity model simulating the porosity distribution inside a spray formed ring preform. The model has been validated against experiments of the spray forming of large diameter IN718 Ni superalloy rings. The modelled preform shape, surface temperature and final porosity distribution showed good agreement with experimental measurements

Lithium-Ion Battery Safety Study Using Multi-Physics Internal Short-Circuit Model (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Kim, G-.H.; Smith, K.; Pesaran, A.

2009-06-01

This presentation outlines NREL's multi-physics simulation study to characterize an internal short by linking and integrating electrochemical cell, electro-thermal, and abuse reaction kinetics models.

Multiphase porous media modelling: A novel approach to predicting food processing performance.

Science.gov (United States)

Khan, Md Imran H; Joardder, M U H; Kumar, Chandan; Karim, M A

2018-03-04

The development of a physics-based model of food processing is essential to improve the quality of processed food and optimize energy consumption. Food materials, particularly plant-based food materials, are complex in nature as they are porous and have hygroscopic properties. A multiphase porous media model for simultaneous heat and mass transfer can provide a realistic understanding of transport processes and thus can help to optimize energy consumption and improve food quality. Although the development of a multiphase porous media model for food processing is a challenging task because of its complexity, many researchers have attempted it. The primary aim of this paper is to present a comprehensive review of the multiphase models available in the literature for different methods of food processing, such as drying, frying, cooking, baking, heating, and roasting. A critical review of the parameters that should be considered for multiphase modelling is presented which includes input parameters, material properties, simulation techniques and the hypotheses. A discussion on the general trends in outcomes, such as moisture saturation, temperature profile, pressure variation, and evaporation patterns, is also presented. The paper concludes by considering key issues in the existing multiphase models and future directions for development of multiphase models.

Integration of topological modification within the modeling of multi-physics systems: Application to a Pogo-stick

Science.gov (United States)

Abdeljabbar Kharrat, Nourhene; Plateaux, Régis; Miladi Chaabane, Mariem; Choley, Jean-Yves; Karra, Chafik; Haddar, Mohamed

2018-05-01

The present work tackles the modeling of multi-physics systems applying a topological approach while proceeding with a new methodology using a topological modification to the structure of systems. Then the comparison with the Magos' methodology is made. Their common ground is the use of connectivity within systems. The comparison and analysis of the different types of modeling show the importance of the topological methodology through the integration of the topological modification to the topological structure of a multi-physics system. In order to validate this methodology, the case of Pogo-stick is studied. The first step consists in generating a topological graph of the system. Then the connectivity step takes into account the contact with the ground. During the last step of this research; the MGS language (Modeling of General System) is used to model the system through equations. Finally, the results are compared to those obtained by MODELICA. Therefore, this proposed methodology may be generalized to model multi-physics systems that can be considered as a set of local elements.

Assessing climate impact on reinforced concrete durability with a multi-physics model

DEFF Research Database (Denmark)

Michel, Alexander; Flint, Madeleine M.

to shorter-term fluctuations in boundary conditions and therefore may underestimate climate change impacts. A highly sensitive fully-coupled, validated, multi-physics model for heat, moisture and ion transport and corrosion was used to assess a reinforced concrete structure located in coastal Norfolk...

Tightly Coupled Multiphysics Algorithm for Pebble Bed Reactors

International Nuclear Information System (INIS)

Park, HyeongKae; Knoll, Dana; Gaston, Derek; Martineau, Richard

2010-01-01

We have developed a tightly coupled multiphysics simulation tool for the pebble-bed reactor (PBR) concept, a type of Very High-Temperature gas-cooled Reactor (VHTR). The simulation tool, PRONGHORN, takes advantages of the Multiphysics Object-Oriented Simulation Environment library, and is capable of solving multidimensional thermal-fluid and neutronics problems implicitly with a Newton-based approach. Expensive Jacobian matrix formation is alleviated via the Jacobian-free Newton-Krylov method, and physics-based preconditioning is applied to minimize Krylov iterations. Motivation for the work is provided via analysis and numerical experiments on simpler multiphysics reactor models. We then provide detail of the physical models and numerical methods in PRONGHORN. Finally, PRONGHORN's algorithmic capability is demonstrated on a number of PBR test cases.

Multiscale Multiphysics and Multidomain Models I: Basic Theory.

Science.gov (United States)

Wei, Guo-Wei

2013-12-01

This work extends our earlier two-domain formulation of a differential geometry based multiscale paradigm into a multidomain theory, which endows us the ability to simultaneously accommodate multiphysical descriptions of aqueous chemical, physical and biological systems, such as fuel cells, solar cells, nanofluidics, ion channels, viruses, RNA polymerases, molecular motors and large macromolecular complexes. The essential idea is to make use of the differential geometry theory of surfaces as a natural means to geometrically separate the macroscopic domain of solvent from the microscopic domain of solute, and dynamically couple continuum and discrete descriptions. Our main strategy is to construct energy functionals to put on an equal footing of multiphysics, including polar (i.e., electrostatic) solvation, nonpolar solvation, chemical potential, quantum mechanics, fluid mechanics, molecular mechanics, coarse grained dynamics and elastic dynamics. The variational principle is applied to the energy functionals to derive desirable governing equations, such as multidomain Laplace-Beltrami (LB) equations for macromolecular morphologies, multidomain Poisson-Boltzmann (PB) equation or Poisson equation for electrostatic potential, generalized Nernst-Planck (NP) equations for the dynamics of charged solvent species, generalized Navier-Stokes (NS) equation for fluid dynamics, generalized Newton's equations for molecular dynamics (MD) or coarse-grained dynamics and equation of motion for elastic dynamics. Unlike the classical PB equation, our PB equation is an integral-differential equation due to solvent-solute interactions. To illustrate the proposed formalism, we have explicitly constructed three models, a multidomain solvation model, a multidomain charge transport model and a multidomain chemo-electro-fluid-MD-elastic model. Each solute domain is equipped with distinct surface tension, pressure, dielectric function, and charge density distribution. In addition to long

Validation of a 3D multi-physics model for unidirectional silicon solidification

NARCIS (Netherlands)

Simons, P.; Lankhorst, A.M.; Habraken, A.; Faber, A.J.; Tiuleanu, D.; Pingel, R.

2012-01-01

A model for transient movements of solidification fronts has been added to X-stream, an existing multi-physics simulation program for high temperature processes with flow and chemical reactions. The implementation uses an enthalpy formulation and works on fixed grids. First we show the results of a

Advanced Multiphysics Thermal-Hydraulics Models for the High Flux Isotope Reactor

Energy Technology Data Exchange (ETDEWEB)

Jain, Prashant K [ORNL; Freels, James D [ORNL

2015-01-01

Engineering design studies to determine the feasibility of converting the High Flux Isotope Reactor (HFIR) from using highly enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL). This work is part of an effort sponsored by the US Department of Energy (DOE) Reactor Conversion Program. HFIR is a very high flux pressurized light-water-cooled and moderated flux-trap type research reactor. HFIR s current missions are to support neutron scattering experiments, isotope production, and materials irradiation, including neutron activation analysis. Advanced three-dimensional multiphysics models of HFIR fuel were developed in COMSOL software for safety basis (worst case) operating conditions. Several types of physics including multilayer heat conduction, conjugate heat transfer, turbulent flows (RANS model) and structural mechanics were combined and solved for HFIR s inner and outer fuel elements. Alternate design features of the new LEU fuel were evaluated using these multiphysics models. This work led to a new, preliminary reference LEU design that combines a permanent absorber in the lower unfueled region of all of the fuel plates, a burnable absorber in the inner element side plates, and a relocated and reshaped (but still radially contoured) fuel zone. Preliminary results of estimated thermal safety margins are presented. Fuel design studies and model enhancement continue.

Dynamical and quasi-static multi-physical models of a diesel internal combustion engine using Energetic Macroscopic Representation

International Nuclear Information System (INIS)

Horrein, L.; Bouscayrol, A.; Cheng, Y.; El Fassi, M.

2015-01-01

Highlights: • Internal Combustion Engine (ICE) dynamical and static models. • Organization of ICE model using Energetic Macroscopic Representation. • Description of the distribution of the chemical, thermal and mechanical power. • Implementation of the ICE model in a global vehicle model. - Abstract: In the simulation of new vehicles, the Internal Combustion Engine (ICE) is generally modeled by a static map. This model yields the mechanical power and the fuel consumption. But some studies require the heat energy from the ICE to be considered (i.e. waste heat recovery, thermal regulation of the cabin). A dynamical multi-physical model of a diesel engine is developed to consider its heat energy. This model is organized using Energetic Macroscopic Representation (EMR) in order to be interconnected to other various models of vehicle subsystems. An experimental validation is provided. Moreover a multi-physical quasi-static model is also derived. According to different modeling aims, a comparison of the dynamical and the quasi-static model is discussed in the case of the simulation of a thermal vehicle. These multi-physical models with different simulation time consumption provide good basis for studying the effects of the thermal energy on the vehicle behaviors, including the possibilities of waste heat recovery

Multi-physics Model for the Aging Prediction of a Vanadium Redox Flow Battery System

International Nuclear Information System (INIS)

Merei, Ghada; Adler, Sophie; Magnor, Dirk; Sauer, Dirk Uwe

2015-01-01

Highlights: • Present a multi-physics model of vanadium redox-flow battery. • This model is essential for aging prediction. • It is applicable for VRB system of different power and capacity ratings. • Good results comparing with current research in this field. - Abstract: The all-vanadium redox-flow battery is an attractive candidate to compensate the fluctuations of non-dispatchable renewable energy generation. While several models for vanadium redox batteries have been described yet, no model has been published, which is adequate for the aging prediction. Therefore, the present paper presents a multi-physics model which determines all parameters that are essential for an aging prediction. In a following paper, the corresponding aging model of vanadium redox flow battery (VRB) is described. The model combines existing models for the mechanical losses and temperature development with new approaches for the batteries side reactions. The model was implemented in Matlab/Simulink. The modeling results presented in the paper prove to be consistent with the experimental results of other research groups

Constitutive relationships and models in continuum theories of multiphase flows

International Nuclear Information System (INIS)

Decker, R.

1989-09-01

In April, 1989, a workshop on constitutive relationships and models in continuum theories of multiphase flows was held at NASA's Marshall Space Flight Center. Topics of constitutive relationships for the partial or per phase stresses, including the concept of solid phase pressure are discussed. Models used for the exchange of mass, momentum, and energy between the phases in a multiphase flow are also discussed. The program, abstracts, and texts of the presentations from the workshop are included

Towards an Industrial Application of Statistical Uncertainty Analysis Methods to Multi-physical Modelling and Safety Analyses

International Nuclear Information System (INIS)

Zhang, Jinzhao; Segurado, Jacobo; Schneidesch, Christophe

2013-01-01

Since 1980's, Tractebel Engineering (TE) has being developed and applied a multi-physical modelling and safety analyses capability, based on a code package consisting of the best estimate 3D neutronic (PANTHER), system thermal hydraulic (RELAP5), core sub-channel thermal hydraulic (COBRA-3C), and fuel thermal mechanic (FRAPCON/FRAPTRAN) codes. A series of methodologies have been developed to perform and to license the reactor safety analysis and core reload design, based on the deterministic bounding approach. Following the recent trends in research and development as well as in industrial applications, TE has been working since 2010 towards the application of the statistical sensitivity and uncertainty analysis methods to the multi-physical modelling and licensing safety analyses. In this paper, the TE multi-physical modelling and safety analyses capability is first described, followed by the proposed TE best estimate plus statistical uncertainty analysis method (BESUAM). The chosen statistical sensitivity and uncertainty analysis methods (non-parametric order statistic method or bootstrap) and tool (DAKOTA) are then presented, followed by some preliminary results of their applications to FRAPCON/FRAPTRAN simulation of OECD RIA fuel rod codes benchmark and RELAP5/MOD3.3 simulation of THTF tests. (authors)

Exploring a Multiphysics Resolution Approach for Additive Manufacturing

Science.gov (United States)

Estupinan Donoso, Alvaro Antonio; Peters, Bernhard

2018-06-01

Metal additive manufacturing (AM) is a fast-evolving technology aiming to efficiently produce complex parts while saving resources. Worldwide, active research is being performed to solve the existing challenges of this growing technique. Constant computational advances have enabled multiscale and multiphysics numerical tools that complement the traditional physical experimentation. In this contribution, an advanced discrete-continuous concept is proposed to address the physical phenomena involved during laser powder bed fusion. The concept treats powder as discrete by the extended discrete element method, which predicts the thermodynamic state and phase change for each particle. The fluid surrounding is solved with multiphase computational fluid dynamics techniques to determine momentum, heat, gas and liquid transfer. Thus, results track the positions and thermochemical history of individual particles in conjunction with the prevailing fluid phases' temperature and composition. It is believed that this methodology can be employed to complement experimental research by analysis of the comprehensive results, which can be extracted from it to enable AM processes optimization for parts qualification.

CANDU fuel bundle deformation modelling with COMSOL multiphysics

International Nuclear Information System (INIS)

Bell, J.S.; Lewis, B.J.

2012-01-01

Highlights: ► The deformation behaviour of a CANDU fuel bundle was modelled. ► The model has been developed on a commercial finite-element platform. ► Pellet/sheath interaction and end-plate restraint effects were considered. ► The model was benchmarked against the BOW code and a variable-load experiment. - Abstract: A model to describe deformation behaviour of a CANDU 37-element bundle has been developed under the COMSOL Multiphysics finite-element platform. Beam elements were applied to the fuel elements (composed of fuel sheaths and pellets) and endplates in order to calculate the bowing behaviour of the fuel elements. This model is important to help assess bundle-deformation phenomena, which may lead to more restrictive coolant flow through the sub-channels of the horizontally oriented bundle. The bundle model was compared to the BOW code for the occurrence of a dry-out patch, and benchmarked against an out-reactor experiment with a variable load on an outer fuel element.

Modeling reproducibility of porescale multiphase flow experiments

Science.gov (United States)

Ling, B.; Tartakovsky, A. M.; Bao, J.; Oostrom, M.; Battiato, I.

2017-12-01

Multi-phase flow in porous media is widely encountered in geological systems. Understanding immiscible fluid displacement is crucial for processes including, but not limited to, CO2 sequestration, non-aqueous phase liquid contamination and oil recovery. Microfluidic devices and porescale numerical models are commonly used to study multiphase flow in biological, geological, and engineered porous materials. In this work, we perform a set of drainage and imbibition experiments in six identical microfluidic cells to study the reproducibility of multiphase flow experiments. We observe significant variations in the experimental results, which are smaller during the drainage stage and larger during the imbibition stage. We demonstrate that these variations are due to sub-porescale geometry differences in microcells (because of manufacturing defects) and variations in the boundary condition (i.e.,fluctuations in the injection rate inherent to syringe pumps). Computational simulations are conducted using commercial software STAR-CCM+, both with constant and randomly varying injection rate. Stochastic simulations are able to capture variability in the experiments associated with the varying pump injection rate.

Conductance Thin Film Model of Flexible Organic Thin Film Device using COMSOL Multiphysics

Science.gov (United States)

Carradero-Santiago, Carolyn; Vedrine-Pauléus, Josee

We developed a virtual model to analyze the electrical conductivity of multilayered thin films placed above a graphene conducting and flexible polyethylene terephthalate (PET) substrate. The organic layers of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a hole conducting layer, poly(3-hexylthiophene-2,5-diyl) (P3HT), as a p-type, phenyl-C61-butyric acid methyl ester (PCBM) and as n-type, with aluminum as a top conductor. COMSOL Multiphysics was the software we used to develop the virtual model to analyze potential variations and conductivity through the thin-film layers. COMSOL Multiphysics software allows simulation and modeling of physical phenomena represented by differential equations such as heat transfer, fluid flow, electromagnetism, and structural mechanics. In this work, using the AC/DC, electric currents module we defined the geometry of the model and properties for each of the six layers: PET/graphene/PEDOT:PSS/P3HT/PCBM/aluminum. We analyzed the model with varying thicknesses of graphene and active layers (P3HT/PCBM). This simulation allowed us to analyze the electrical conductivity, and visualize the model with varying voltage potential, or bias across the plates, useful for applications in solar cell devices.

Self-assembly of silica microparticles in magnetic multiphase flows: Experiment and simulation

Science.gov (United States)

Li, Xiang; Niu, Xiao-Dong; Li, You; Chen, Mu-Feng

2018-04-01

Dynamic self-assembly, especially self-assembly under magnetic field, is vital not only for its marvelous phenomenon but also for its mechanisms. Revealing the underlying mechanisms is crucial for a deeper understanding of self-assembly. In this paper, several magnetic induced self-assembly experiments by using the mixed magnetic multiphase fluids comprised of silica microspheres were carried out. The relations of the strength of external magnetic field, the inverse magnetorheological effect, and the structures of self-assembled particles were investigated. In addition, a momentum-exchanged immersed boundary-based lattice Boltzmann method (MEIB-LBM) for modeling multi-physical coupling multiphase flows was employed to numerically study the magnetic induced self-assembly process in detail. The present work showed that the external magnetic field can be used to control the form of self-assembly of nonmagnetic microparticles in a chain-like structure, and the self-assembly process can be classified into four stages with magnetic hysteresis, magnetization of nonmagnetic microparticles, self-assembly in chain-like structures, and the stable chain state. The combination of experimental and numerical results could offer a method to control the self-assembled nonmagnetic microparticles, which can provide the technical and theoretical support for the design and fabrication of micro/nanomaterials.

A mathematical model for predicting photo-induced voltage and photostriction of PLZT with coupled multi-physics fields and its application

International Nuclear Information System (INIS)

Huang, J H; Wang, X J; Wang, J

2016-01-01

The primary purpose of this paper is to propose a mathematical model of PLZT ceramic with coupled multi-physics fields, e.g. thermal, electric, mechanical and light field. To this end, the coupling relationships of multi-physics fields and the mechanism of some effects resulting in the photostrictive effect are analyzed theoretically, based on which a mathematical model considering coupled multi-physics fields is established. According to the analysis and experimental results, the mathematical model can explain the hysteresis phenomenon and the variation trend of the photo-induced voltage very well and is in agreement with the experimental curves. In addition, the PLZT bimorph is applied as an energy transducer for a photovoltaic–electrostatic hybrid actuated micromirror, and the relation of the rotation angle and the photo-induced voltage is discussed based on the novel photostrictive mathematical model. (paper)

Modelling organs, tissues, cells and devices using Matlab and Comsol multiphysics

CERN Document Server

Dokos, Socrates

2017-01-01

This book presents a theoretical and practical overview of computational modeling in bioengineering, focusing on a range of applications including electrical stimulation of neural and cardiac tissue, implantable drug delivery, cancer therapy, biomechanics, cardiovascular dynamics, as well as fluid-structure interaction for modelling of organs, tissues, cells and devices. It covers the basic principles of modeling and simulation with ordinary and partial differential equations using MATLAB and COMSOL Multiphysics numerical software. The target audience primarily comprises postgraduate students and researchers, but the book may also be beneficial for practitioners in the medical device industry.

A Multi-Phase Equation of State and Strength Model for Tin

International Nuclear Information System (INIS)

Cox, G. A.

2006-01-01

This paper considers a multi-phase equation of state and a multi-phase strength model for tin in the β, γ and liquid phases. At a phase transition there are changes in volume, energy, and properties of a material that should be included in an accurate model. The strength model will also be affected by a solid-solid phase transition. For many materials there is a lack of experimental data for strength at high pressures making the derivation of strength parameters for some phases difficult. In the case of tin there are longitudinal sound speed data on the Hugoniot available that have been used here in conjunction with a multi-phase equation of state to derive strength parameters for the γ phase, a phase which does not exist at room temperature and pressure

Multiphasic modeling of charged solute transport across articular cartilage: Application of multi-zone finite-bath model.

Science.gov (United States)

Arbabi, Vahid; Pouran, Behdad; Weinans, Harrie; Zadpoor, Amir A

2016-06-14

Charged and uncharged solutes penetrate through cartilage to maintain the metabolic function of chondrocytes and to possibly restore or further breakdown the cartilage tissue in different stages of osteoarthritis. In this study the transport of charged solutes across the various zones of cartilage was quantified, taken into account the physicochemical interactions between the solute and the cartilage constituents. A multiphasic finite-bath finite element (FE) model was developed to simulate equine cartilage diffusion experiments that used a negatively charged contrast agent (ioxaglate) in combination with serial micro-computed tomography (micro-CT) to measure the diffusion. By comparing the FE model with the experimental data both the diffusion coefficient of ioxaglate and the fixed charge density (FCD) were obtained. In the multiphasic model, cartilage was divided into multiple (three) zones to help understand how diffusion coefficient and FCD vary across cartilage thickness. The direct effects of charged solute-FCD interaction on diffusion were investigated by comparing the diffusion coefficients derived from the multiphasic and biphasic-solute models. We found a relationship between the FCD obtained by the multiphasic model and ioxaglate partitioning obtained from micro-CT experiments. Using our multi-zone multiphasic model, diffusion coefficient of the superficial zone was up to ten-fold higher than that of the middle zone, while the FCD of the middle zone was up to almost two-fold higher than that of the superficial zone. In conclusion, the developed finite-bath multiphasic model provides us with a non-destructive method by which we could obtain both diffusion coefficient and FCD of different cartilage zones. The outcomes of the current work will also help understand how charge of the bath affects the diffusion of a charged molecule and also predict the diffusion behavior of a charged solute across articular cartilage. Copyright © 2016 Elsevier Ltd. All

CFD Modeling of a Multiphase Gravity Separator Vessel

KAUST Repository

Narayan, Gautham

2017-05-23

The poster highlights a CFD study that incorporates a combined Eulerian multi-fluid multiphase and a Population Balance Model (PBM) to study the flow inside a typical multiphase gravity separator vessel (GSV) found in oil and gas industry. The simulations were performed using Ansys Fluent CFD package running on KAUST supercomputer, Shaheen. Also, a highlight of a scalability study is presented. The effect of I/O bottlenecks and using Hierarchical Data Format (HDF5) for collective and independent parallel reading of case file is presented. This work is an outcome of a research collaboration on an Aramco project on Shaheen.

CFD Modeling of a Multiphase Gravity Separator Vessel

KAUST Repository

Narayan, Gautham; Khurram, Rooh Ul Amin; Elsaadawy, Ehab

2017-01-01

The poster highlights a CFD study that incorporates a combined Eulerian multi-fluid multiphase and a Population Balance Model (PBM) to study the flow inside a typical multiphase gravity separator vessel (GSV) found in oil and gas industry. The simulations were performed using Ansys Fluent CFD package running on KAUST supercomputer, Shaheen. Also, a highlight of a scalability study is presented. The effect of I/O bottlenecks and using Hierarchical Data Format (HDF5) for collective and independent parallel reading of case file is presented. This work is an outcome of a research collaboration on an Aramco project on Shaheen.

Computational Flow Modeling of Hydrodynamics in Multiphase Trickle-Bed Reactors

Science.gov (United States)

Lopes, Rodrigo J. G.; Quinta-Ferreira, Rosa M.

2008-05-01

This study aims to incorporate most recent multiphase models in order to investigate the hydrodynamic behavior of a TBR in terms of pressure drop and liquid holdup. Taking into account transport phenomena such as mass and heat transfer, an Eulerian k-fluid model was developed resulting from the volume averaging of the continuity and momentum equations and solved for a 3D representation of the catalytic bed. Computational fluid dynamics (CFD) model predicts hydrodynamic parameters quite well if good closures for fluid/fluid and fluid/particle interactions are incorporated in the multiphase model. Moreover, catalytic performance is investigated with the catalytic wet oxidation of a phenolic pollutant.

NREL Multiphysics Modeling Tools and ISC Device for Designing Safer Li-Ion Batteries

Energy Technology Data Exchange (ETDEWEB)

Pesaran, Ahmad A.; Yang, Chuanbo

2016-03-24

The National Renewable Energy Laboratory has developed a portfolio of multiphysics modeling tools to aid battery designers better understand the response of lithium ion batteries to abusive conditions. We will discuss this portfolio, which includes coupled electrical, thermal, chemical, electrochemical, and mechanical modeling. These models can simulate the response of a cell to overheating, overcharge, mechanical deformation, nail penetration, and internal short circuit. Cell-to-cell thermal propagation modeling will be discussed.

Multiphase flow analysis using population balance modeling bubbles, drops and particles

CERN Document Server

Yeoh, Guan Heng; Tu, Jiyuan

2013-01-01

Written by leading multiphase flow and CFD experts, this book enables engineers and researchers to understand the use of PBM and CFD frameworks. Population balance approaches can now be used in conjunction with CFD, effectively driving more efficient and effective multiphase flow processes. Engineers familiar with standard CFD software, including ANSYS-CFX and ANSYS-Fluent, will be able to use the tools and approaches presented in this book in the effective research, modeling and control of multiphase flow problems. Builds a complete understanding of the theory behind the

Three Dimensional Thermal Modeling of Li-Ion Battery Pack Based on Multiphysics and Calorimetric Measurement

DEFF Research Database (Denmark)

Khan, Mohammad Rezwan; Kær, Søren Knudsen

2016-01-01

A three-dimensional multiphysics-based thermal model of a battery pack is presented. The model is intended to demonstrate the cooling mechanism inside the battery pack. Heat transfer (HT) and computational fluid dynamics (CFD) physics are coupled for both time-dependent and steady-state simulatio...

Multiscale and Multiphysics Modeling of Additive Manufacturing of Advanced Materials

Science.gov (United States)

Liou, Frank; Newkirk, Joseph; Fan, Zhiqiang; Sparks, Todd; Chen, Xueyang; Fletcher, Kenneth; Zhang, Jingwei; Zhang, Yunlu; Kumar, Kannan Suresh; Karnati, Sreekar

2015-01-01

The objective of this proposed project is to research and develop a prediction tool for advanced additive manufacturing (AAM) processes for advanced materials and develop experimental methods to provide fundamental properties and establish validation data. Aircraft structures and engines demand materials that are stronger, useable at much higher temperatures, provide less acoustic transmission, and enable more aeroelastic tailoring than those currently used. Significant improvements in properties can only be achieved by processing the materials under nonequilibrium conditions, such as AAM processes. AAM processes encompass a class of processes that use a focused heat source to create a melt pool on a substrate. Examples include Electron Beam Freeform Fabrication and Direct Metal Deposition. These types of additive processes enable fabrication of parts directly from CAD drawings. To achieve the desired material properties and geometries of the final structure, assessing the impact of process parameters and predicting optimized conditions with numerical modeling as an effective prediction tool is necessary. The targets for the processing are multiple and at different spatial scales, and the physical phenomena associated occur in multiphysics and multiscale. In this project, the research work has been developed to model AAM processes in a multiscale and multiphysics approach. A macroscale model was developed to investigate the residual stresses and distortion in AAM processes. A sequentially coupled, thermomechanical, finite element model was developed and validated experimentally. The results showed the temperature distribution, residual stress, and deformation within the formed deposits and substrates. A mesoscale model was developed to include heat transfer, phase change with mushy zone, incompressible free surface flow, solute redistribution, and surface tension. Because of excessive computing time needed, a parallel computing approach was also tested. In addition

A Radiative Transfer Modeling Methodology in Gas-Liquid Multiphase Flow Simulations

Directory of Open Access Journals (Sweden)

Gautham Krishnamoorthy

2014-01-01

Full Text Available A methodology for performing radiative transfer calculations in computational fluid dynamic simulations of gas-liquid multiphase flows is presented. By considering an externally irradiated bubble column photoreactor as our model system, the bubble scattering coefficients were determined through add-on functions by employing as inputs the bubble volume fractions, number densities, and the fractional contribution of each bubble size to the bubble volume from four different multiphase modeling options. The scattering coefficient profiles resulting from the models were significantly different from one another and aligned closely with their predicted gas-phase volume fraction distributions. The impacts of the multiphase modeling option, initial bubble diameter, and gas flow rates on the radiation distribution patterns within the reactor were also examined. An increase in air inlet velocities resulted in an increase in the fraction of larger sized bubbles and their contribution to the scattering coefficient. However, the initial bubble sizes were found to have the strongest impact on the radiation field.

Eulerian Multiphase Population Balance Model of Atomizing, Swirling Flows

Directory of Open Access Journals (Sweden)

Narayana P. Rayapati

2011-06-01

Full Text Available An Eulerian/Eulerian multiphase flow model coupled with a population balance model is used as the basis for numerical simulation of atomization in swirling flows. The objective of this exercise is to develop a methodology capable of predicting the local point-wise drop size distribution in a spray, such as would be measured by the Phase Doppler Particle Analyzer (PDA. Model predictions are compared to experimental measurements of particle size distributions in an air-blast atomizer spray to demonstrate good qualitative and quantitative agreement. It is observed that the dependence of velocity on drop size inherent in a multiphase description of the drop cloud appears necessary to capture some features of the experimental data. Using this model, we demonstrate the relative contributions of secondary atomization and transport to the variation observed in the downstream spray drop size distribution.

A multiphase compressible model for the simulation of multiphase flows

International Nuclear Information System (INIS)

Caltagirone, J.P.; Vincent, St.; Caruyer, C.

2011-01-01

A compressible model able to manage incompressible two-phase flows as well as compressible motions is proposed. After a presentation of the multiphase compressible concept, the new model and related numerical methods are detailed on fixed structured grids. The presented model is a 1-fluid model with a reformulated mass conservation equation which takes into account the effects of compressibility. The coupling between pressure and flow velocity is ensured by introducing mass conservation terms in the momentum and energy equations. The numerical model is then validated with four test cases involving the compression of an air bubble by water, the liquid injection in a closed cavity filled with air, a bubble subjected to an ultrasound field and finally the oscillations of a deformed air bubble in melted steel. The numerical results are compared with analytical results and convergence orders in space are provided. (authors)

The multiphase physics of sea ice: a review for model developers

Directory of Open Access Journals (Sweden)

E. C. Hunke

2011-11-01

Full Text Available Rather than being solid throughout, sea ice contains liquid brine inclusions, solid salts, microalgae, trace elements, gases, and other impurities which all exist in the interstices of a porous, solid ice matrix. This multiphase structure of sea ice arises from the fact that the salt that exists in seawater cannot be incorporated into lattice sites in the pure ice component of sea ice, but remains in liquid solution. Depending on the ice permeability (determined by temperature, salinity and gas content, this brine can drain from the ice, taking other sea ice constituents with it. Thus, sea ice salinity and microstructure are tightly interconnected and play a significant role in polar ecosystems and climate. As large-scale climate modeling efforts move toward "earth system" simulations that include biological and chemical cycles, renewed interest in the multiphase physics of sea ice has strengthened research initiatives to observe, understand and model this complex system. This review article provides an overview of these efforts, highlighting known difficulties and requisite observations for further progress in the field. We focus on mushy layer theory, which describes general multiphase materials, and on numerical approaches now being explored to model the multiphase evolution of sea ice and its interaction with chemical, biological and climate systems.

Modeling variability in porescale multiphase flow experiments

Science.gov (United States)

Ling, Bowen; Bao, Jie; Oostrom, Mart; Battiato, Ilenia; Tartakovsky, Alexandre M.

2017-07-01

Microfluidic devices and porescale numerical models are commonly used to study multiphase flow in biological, geological, and engineered porous materials. In this work, we perform a set of drainage and imbibition experiments in six identical microfluidic cells to study the reproducibility of multiphase flow experiments. We observe significant variations in the experimental results, which are smaller during the drainage stage and larger during the imbibition stage. We demonstrate that these variations are due to sub-porescale geometry differences in microcells (because of manufacturing defects) and variations in the boundary condition (i.e., fluctuations in the injection rate inherent to syringe pumps). Computational simulations are conducted using commercial software STAR-CCM+, both with constant and randomly varying injection rates. Stochastic simulations are able to capture variability in the experiments associated with the varying pump injection rate.

Predictive modeling of coupled multi-physics systems: II. Illustrative application to reactor physics

International Nuclear Information System (INIS)

Cacuci, Dan Gabriel; Badea, Madalina Corina

2014-01-01

Highlights: • We applied the PMCMPS methodology to a paradigm neutron diffusion model. • We underscore the main steps in applying PMCMPS to treat very large coupled systems. • PMCMPS reduces the uncertainties in the optimally predicted responses and model parameters. • PMCMPS is for sequentially treating coupled systems that cannot be treated simultaneously. - Abstract: This work presents paradigm applications to reactor physics of the innovative mathematical methodology for “predictive modeling of coupled multi-physics systems (PMCMPS)” developed by Cacuci (2014). This methodology enables the assimilation of experimental and computational information and computes optimally predicted responses and model parameters with reduced predicted uncertainties, taking fully into account the coupling terms between the multi-physics systems, but using only the computational resources that would be needed to perform predictive modeling on each system separately. The paradigm examples presented in this work are based on a simple neutron diffusion model, chosen so as to enable closed-form solutions with clear physical interpretations. These paradigm examples also illustrate the computational efficiency of the PMCMPS, which enables the assimilation of additional experimental information, with a minimal increase in computational resources, to reduce the uncertainties in predicted responses and best-estimate values for uncertain model parameters, thus illustrating how very large systems can be treated without loss of information in a sequential rather than simultaneous manner

Advancement and Application of Multi-Phase CFD Modeling to High Speed Supercavitating Flows

Science.gov (United States)

2013-08-13

October 2008 - December 2013 4. TITLE AND SUBTITLE Advancement and Application of Multi-Phase CFD Modeling to High Speed Supercavitating Flows...influence cavity hysteresis behavior. These observations are used to guide improved supercavitating -vehicle analyses including numerical predictions...experiments, and modeling 15. SUBJECT TERMS supercavitation , computational fluid dynamics, multiphase flow 16. SECURITY CLASSIFICATION OF: a

Twenty-five years of modeling multiphase flow and heat transfer

International Nuclear Information System (INIS)

Lyczkowski, R.W.

1999-01-01

This presentation will cover some of the highlights of multiphase modeling in collaboration with Professor Dimitri Gidaspow (DG) over the last roughly twenty-five years. It all started in 1972 in Idaho Falls with Charles Solbrig, who planned and initiated a project for the former USAEC to develop a computer code to replace RELAP4 to analyze the loss of coolant accident (LOCA). DG spent his sabbatical on the project in 1973. One highlight was the discovery of complex characteristics, the implications of which are still pondered by some. Fluidization research began in 1978 when the author collaboratively developed a step-by-step building-block approach to understanding the hydrodynamics of fluidized beds, an approach closely coupled to validation experiments. A grant from the USDOE to study solids circulation around a jet in a fluidized bed was awarded to DG in 1978. Following that, grants from GRI, NSF, and a contract from Westinghouse Electric Corp. allowed the early work to continue. Progress was slow since computer costs were high. Subsequent continuing support from the USDOE, NSF, EPRI, and industry has allowed research to continue, as has his collaboration. A highlight of this collaboration was the development of the monolayer energy dissipation (MED) erosion model. Multiphase flow and fluidization theory took quantum leaps with the publication of DG's Multiphase Flow and Fluidization: Continuum and Kinetic Theory Descriptions (MFF), Academic Press, San Diego (1994), for which there is essentially no competition. Only the late Professor S.L. Soo's Particulates and Continuum: Multiphase Fluid Dynamics, Hemisphere Publishing Corp., New York (1989), a textbook version of the classic monograph Multiphase Fluid Dynamics, Science Press, Beijing, China (1990), comes close. In MFF, the kinetic theory of granular flow has evolved as a potentially viable adjunct to the continuum multiphase theory, of which fluidization is one important manifestation. It must be

Multiphysics modelling and experimental validation of an air-coupled array of PMUTs with residual stresses

Science.gov (United States)

Massimino, G.; Colombo, A.; D'Alessandro, L.; Procopio, F.; Ardito, R.; Ferrera, M.; Corigliano, A.

2018-05-01

In this paper a complete multiphysics modelling via the finite element method (FEM) of an air-coupled array of piezoelectric micromachined ultrasonic transducers (PMUT) and its experimental validation are presented. Two numerical models are described for the single transducer, axisymmetric and 3D, with the following features: the presence of fabrication induced residual stresses, which determine a non-linear initial deformed configuration of the diaphragm and a substantial fundamental mode frequency shift; the multiple coupling between different physics, namely electro-mechanical coupling for the piezo-electric model, thermo-acoustic-structural interaction and thermo-acoustic-pressure interaction for the waves propagation in the surrounding fluid. The model for the single transducer is enhanced considering the full set of PMUTs belonging to the silicon dye in a 4 × 4 array configuration. The results of the numerical multiphysics models are compared with experimental ones in terms of the initial static pre-deflection, of the diaphragm central point spectrum and of the sound intensity at 3.5 cm on the vertical direction along the axis of the diaphragm.

Slush Fund: Modeling the Multiphase Physics of Oceanic Ices

Science.gov (United States)

Buffo, J.; Schmidt, B. E.

2016-12-01

The prevalence of ice interacting with an ocean, both on Earth and throughout the solar system, and its crucial role as the mediator of exchange between the hydrosphere below and atmosphere above, have made quantifying the thermodynamic, chemical, and physical properties of the ice highly desirable. While direct observations of these quantities exist, their scarcity increases with the difficulty of obtainment; the basal surfaces of terrestrial ice shelves remain largely unexplored and the icy interiors of moons like Europa and Enceladus have never been directly observed. Our understanding of these entities thus relies on numerical simulation, and the efficacy of their incorporation into larger systems models is dependent on the accuracy of these initial simulations. One characteristic of seawater, likely shared by the oceans of icy moons, is that it is a solution. As such, when it is frozen a majority of the solute is rejected from the forming ice, concentrating in interstitial pockets and channels, producing a two-component reactive porous media known as a mushy layer. The multiphase nature of this layer affects the evolution and dynamics of the overlying ice mass. Additionally ice can form in the water column and accrete onto the basal surface of these ice masses via buoyancy driven sedimentation as frazil or platelet ice. Numerical models hoping to accurately represent ice-ocean interactions should include the multiphase behavior of these two phenomena. While models of sea ice have begun to incorporate multiphase physics into their capabilities, no models of ice shelves/shells explicitly account for the two-phase behavior of the ice-ocean interface. Here we present a 1D multiphase model of floating oceanic ice that includes parameterizations of both density driven advection within the `mushy layer' and buoyancy driven sedimentation. The model is validated against contemporary sea ice models and observational data. Environmental stresses such as supercooling and

Multiphysics Model Development and the Core Analysis for In Situ Breeding and Burning Reactor

Directory of Open Access Journals (Sweden)

Shengyi Si

2013-01-01

Full Text Available The in situ breeding and burning reactor (ISBBR, which makes use of the outstanding breeding capability of metallic pellet and the excellent irradiation-resistant performance of SiCf/SiC ceramic composites cladding, can approach the design purpose of ultralong cycle and ultrahigh burnup and maintain stable radial power distribution during the cycle life without refueling and shuffling. Since the characteristics of the fuel pellet and cladding are different from the traditional fuel rod of ceramic pellet and metallic cladding, the multiphysics behaviors in ISBBR are also quite different. A computer code, named TANG, to model the specific multiphysics behaviors in ISBBR has been developed. The primary calculation results provided by TANG demonstrate that ISBBR has an excellent comprehensive performance of GEN-IV and a great development potential.

A Posteriori Analysis of Adaptive Multiscale Operator Decomposition Methods for Multiphysics Problems

Energy Technology Data Exchange (ETDEWEB)

Donald Estep; Michael Holst; Simon Tavener

2010-02-08

This project was concerned with the accurate computational error estimation for numerical solutions of multiphysics, multiscale systems that couple different physical processes acting across a large range of scales relevant to the interests of the DOE. Multiscale, multiphysics models are characterized by intimate interactions between different physics across a wide range of scales. This poses significant computational challenges addressed by the proposal, including: (1) Accurate and efficient computation; (2) Complex stability; and (3) Linking different physics. The research in this project focused on Multiscale Operator Decomposition methods for solving multiphysics problems. The general approach is to decompose a multiphysics problem into components involving simpler physics over a relatively limited range of scales, and then to seek the solution of the entire system through some sort of iterative procedure involving solutions of the individual components. MOD is a very widely used technique for solving multiphysics, multiscale problems; it is heavily used throughout the DOE computational landscape. This project made a major advance in the analysis of the solution of multiscale, multiphysics problems.

Coupled Multi-physical Simulations for the Assessment of Nuclear Waste Repository Concepts: Modeling, Software Development and Simulation

Science.gov (United States)

Massmann, J.; Nagel, T.; Bilke, L.; Böttcher, N.; Heusermann, S.; Fischer, T.; Kumar, V.; Schäfers, A.; Shao, H.; Vogel, P.; Wang, W.; Watanabe, N.; Ziefle, G.; Kolditz, O.

2016-12-01

As part of the German site selection process for a high-level nuclear waste repository, different repository concepts in the geological candidate formations rock salt, clay stone and crystalline rock are being discussed. An open assessment of these concepts using numerical simulations requires physical models capturing the individual particularities of each rock type and associated geotechnical barrier concept to a comparable level of sophistication. In a joint work group of the Helmholtz Centre for Environmental Research (UFZ) and the German Federal Institute for Geosciences and Natural Resources (BGR), scientists of the UFZ are developing and implementing multiphysical process models while BGR scientists apply them to large scale analyses. The advances in simulation methods for waste repositories are incorporated into the open-source code OpenGeoSys. Here, recent application-driven progress in this context is highlighted. A robust implementation of visco-plasticity with temperature-dependent properties into a framework for the thermo-mechanical analysis of rock salt will be shown. The model enables the simulation of heat transport along with its consequences on the elastic response as well as on primary and secondary creep or the occurrence of dilatancy in the repository near field. Transverse isotropy, non-isothermal hydraulic processes and their coupling to mechanical stresses are taken into account for the analysis of repositories in clay stone. These processes are also considered in the near field analyses of engineered barrier systems, including the swelling/shrinkage of the bentonite material. The temperature-dependent saturation evolution around the heat-emitting waste container is described by different multiphase flow formulations. For all mentioned applications, we illustrate the workflow from model development and implementation, over verification and validation, to repository-scale application simulations using methods of high performance computing.

Multidomain multiphase fluid mechanics

International Nuclear Information System (INIS)

Sha, W.T.; Soo, S.L.

1976-10-01

A set of multiphase field equations--conversion of mass, momentum and energy--based on multiphase mechanics is developed. Multiphase mechanics applies to mixtures of phases which are separated by interfaces and are mutually exclusive. Based on the multiphase mechanics formulation, additional terms appear in the field equations when the physical size of the dispersed phase (bubble or droplet) is many times larger than the inter-molecular spacing. These terms are the inertial coupling due to virtual mass and the additional viscous coupling due to unsteadiness of the flow field. The multiphase formulation given here takes into account the discreteness of particles of dispersed phases and, at the same time, the necessity of the distributive representation of field variables via space-time averaging when handling a large number of particles. The provision for multidomain transition further permits us to treat dispersed phases which are large compared to the characteristic dimension of the flow system via interdomain relations. The multidomain multiphase approach provides a framework for us to model the various flow regimes. Because some of the transport parameters associated with the system equations are not well known at the present time, an idealized two-domain two-phase solution approach is proposed as a first step. Finally, comparisons are made between the field equations formulated based on the multidomain-multiphase fluid mechanics and the pertinent existing models, and their relative significances are discussed. The desirability of consistent approximation and simplifications possible for dilute suspensions are discussed

Invasion percolation of single component, multiphase fluids with lattice Boltzmann models

International Nuclear Information System (INIS)

Sukop, M.C.; Or, Dani

2003-01-01

Application of the lattice Boltzmann method (LBM) to invasion percolation of single component multiphase fluids in porous media offers an opportunity for more realistic modeling of the configurations and dynamics of liquid/vapor and liquid/solid interfaces. The complex geometry of connected paths in standard invasion percolation models arises solely from the spatial arrangement of simple elements on a lattice. In reality, fluid interfaces and connectivity in porous media are naturally controlled by the details of the pore geometry, its dynamic interaction with the fluid, and the ambient fluid potential. The multiphase LBM approach admits realistic pore geometry derived from imaging techniques and incorporation of realistic hydrodynamics into invasion percolation models

A MULTIDIMENSIONAL AND MULTIPHYSICS APPROACH TO NUCLEAR FUEL BEHAVIOR SIMULATION

Energy Technology Data Exchange (ETDEWEB)

R. L. Williamson; J. D. Hales; S. R. Novascone; M. R. Tonks; D. R. Gaston; C. J. Permann; D. Andrs; R. C. Martineau

2012-04-01

Important aspects of fuel rod behavior, for example pellet-clad mechanical interaction (PCMI), fuel fracture, oxide formation, non-axisymmetric cooling, and response to fuel manufacturing defects, are inherently multidimensional in addition to being complicated multiphysics problems. Many current modeling tools are strictly 2D axisymmetric or even 1.5D. This paper outlines the capabilities of a new fuel modeling tool able to analyze either 2D axisymmetric or fully 3D models. These capabilities include temperature-dependent thermal conductivity of fuel; swelling and densification; fuel creep; pellet fracture; fission gas release; cladding creep; irradiation growth; and gap mechanics (contact and gap heat transfer). The need for multiphysics, multidimensional modeling is then demonstrated through a discussion of results for a set of example problems. The first, a 10-pellet rodlet, demonstrates the viability of the solution method employed. This example highlights the effect of our smeared cracking model and also shows the multidimensional nature of discrete fuel pellet modeling. The second example relies on our the multidimensional, multiphysics approach to analyze a missing pellet surface problem. As a final example, we show a lower-length-scale simulation coupled to a continuum-scale simulation.

Multiphysics Numerical Modeling of a Fin and Tube Heat Exchanger

DEFF Research Database (Denmark)

Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

2015-01-01

In the present research work, a modeling effort to predict the performance of a liquid-gas type fin and tube heat exchanger design is made. Three dimensional (3D) steady state numerical model is developed using commercial software COMSOL Multiphysics based on finite element method (FEM......). For the purposes here, only gas flowing over the fin side is simulated assuming constant inner tube wall temperature. The study couples conjugate heat transfer mechanism with turbulent flow in order to describe the temperature and velocity profile. In addition, performance characteristics of the heat exchanger...... design in terms of heat transfer and pressure loss are determined by parameters such as overall heat transfer coefficient, Colburn j-factor, flow resistance factor, and efficiency index. The model provides useful insights necessary for optimization of heat exchanger design....

Transient multi-physics analysis of a magnetorheological shock absorber with the inverse Jiles-Atherton hysteresis model

Science.gov (United States)

Zheng, Jiajia; Li, Yancheng; Li, Zhaochun; Wang, Jiong

2015-10-01

This paper presents multi-physics modeling of an MR absorber considering the magnetic hysteresis to capture the nonlinear relationship between the applied current and the generated force under impact loading. The magnetic field, temperature field, and fluid dynamics are represented by the Maxwell equations, conjugate heat transfer equations, and Navier-Stokes equations. These fields are coupled through the apparent viscosity and the magnetic force, both of which in turn depend on the magnetic flux density and the temperature. Based on a parametric study, an inverse Jiles-Atherton hysteresis model is used and implemented for the magnetic field simulation. The temperature rise of the MR fluid in the annular gap caused by core loss (i.e. eddy current loss and hysteresis loss) and fluid motion is computed to investigate the current-force behavior. A group of impulsive tests was performed for the manufactured MR absorber with step exciting currents. The numerical and experimental results showed good agreement, which validates the effectiveness of the proposed multi-physics FEA model.

A multiphase electrokinetic flow model for electrolytes with liquid/liquid interfaces

Energy Technology Data Exchange (ETDEWEB)

Berry, J.D., E-mail: joe.d.berry@gmail.com; Davidson, M.R., E-mail: m.davidson@unimelb.edu.au; Harvie, D.J.E., E-mail: daltonh@unimelb.edu.au

2013-10-15

A numerical model for electrokinetic flow of multiphase systems with deformable interfaces is presented, based on a combined level set-volume of fluid technique. A new feature is a multiphase formulation of the Nernst–Planck transport equation for advection, diffusion and conduction of individual charge carrier species that ensures their conservation in each fluid phase. The numerical model is validated against the analytical results of Zholkovskij et al. (2002) [1], and results for the problem of two drops coalescing in the presence of mobile charge carriers are presented. The time taken for two drops containing ions to coalesce decreases with increasing ion concentration.

Multiphase region of helimagnetic superlattices at low temperature in an extended six-state clock model

Science.gov (United States)

Lovelady, D. C.; Harper, H. M.; Brodsky, I. E.; Rabson, D. A.

2006-05-01

The variety of magnetic phases observed in rare-earth heterostructures at low temperatures (Jehan et al 1993 Phys. Rev. B 48 5594-606), such as Ho/Y, may be elucidated by an ANNNI-like model Hamiltonian. In previous work modelling bulk Ho (Seno, Rabson and Yeomans 1993 J. Phys. A: Math. Gen. 26 4887-905), such a Hamiltonian with a one-dimensional parameter space produced a single multiphase point. In contrast, the parameter space of the heterostructure model is three dimensional, and instead of an isolated multiphase point, we find two-dimensional multiphase regions. In an example of Villain's 'order from disorder' (Villain, Bidaux, Carton and Conte 1980 J. Physique 41 1263-72 Pimpinelli, Uimin and Villain 1991 J. Phys.: Condens. Matter 3 4693-719), an infinitesimal temperature breaks the ground-state degeneracy. In first order of a low-temperature expansion, we find that the degeneracy is broken everywhere in a multiphase region except on a line. A segment of the line appears to remain multiphase to all orders in a low-temperature expansion when the number L of magnetic layers between non-magnetic spacers is 4 but not for other values of L. For L = 4, the hierarchy of phases more closely resembles that in the ANNNI model than in the bulk six-state clock model on which the present model is based.

Multiphase region of helimagnetic superlattices at low temperature in an extended six-state clock model

International Nuclear Information System (INIS)

Lovelady, D C; Harper, H M; Brodsky, I E; Rabson, D A

2006-01-01

The variety of magnetic phases observed in rare-earth heterostructures at low temperatures (Jehan et al 1993 Phys. Rev. B 48 5594-606), such as Ho/Y, may be elucidated by an ANNNI-like model Hamiltonian. In previous work modelling bulk Ho (Seno, Rabson and Yeomans 1993 J. Phys. A: Math. Gen. 26 4887-905), such a Hamiltonian with a one-dimensional parameter space produced a single multiphase point. In contrast, the parameter space of the heterostructure model is three dimensional, and instead of an isolated multiphase point, we find two-dimensional multiphase regions. In an example of Villain's 'order from disorder' (Villain, Bidaux, Carton and Conte 1980 J. Physique 41 1263-72; Pimpinelli, Uimin and Villain 1991 J. Phys.: Condens. Matter 3 4693-719), an infinitesimal temperature breaks the ground-state degeneracy. In first order of a low-temperature expansion, we find that the degeneracy is broken everywhere in a multiphase region except on a line. A segment of the line appears to remain multiphase to all orders in a low-temperature expansion when the number L of magnetic layers between non-magnetic spacers is 4 but not for other values of L. For L = 4, the hierarchy of phases more closely resembles that in the ANNNI model than in the bulk six-state clock model on which the present model is based

Multi-Phase Modeling of Rainbird Water Injection

Science.gov (United States)

Vu, Bruce T.; Moss, Nicholas; Sampson, Zoe

2014-01-01

This paper describes the use of a Volume of Fluid (VOF) multiphase model to simulate the water injected from a rainbird nozzle used in the sound suppression system during launch. The simulations help determine the projectile motion for different water flow rates employed at the pad, as it is critical to know if water will splash on the first-stage rocket engine during liftoff.

Modeling and simulation of multiphase multicomponent multiphysics porous media flows in the context of chemical enhanced oil recovery

Science.gov (United States)

Dutta, Sourav; Daripa, Prabir; Fluids Team

2015-11-01

One of the most important methods of chemical enhanced oil recovery (EOR) involves the use of complex flooding schemes comprising of various layers of fluids mixed with suitable amounts of polymer or surfactant or both. The fluid flow is characterized by the spontaneous formation of complex viscous fingering patterns which is considered detrimental to oil recovery. Here we numerically study the physics of such EOR processes using a modern, hybrid method based on a combination of a discontinuous, multiscale finite element formulation and the method of characteristics. We investigate the effect of different types of heterogeneity on the fingering mechanism of these complex multiphase flows and determine the impact on oil recovery. We also study the effect of surfactants on the dynamics of the flow via reduction of capillary forces and increase in relative permeabilities. Supported by the grant NPRP 08-777-1-141 from the Qatar National Research Fund (a member of The Qatar Foundation).

Euler-Lagrange modeling of the hydrodynamics of dense multiphase flows

NARCIS (Netherlands)

Padding, J.T.; Deen, N.G.; Peters, E. A. J. F.; Kuipers, J. A. M.

2015-01-01

The large-scale hydrodynamic behavior of relatively dense dispersed multiphase flows, such as encountered in fluidized beds, bubbly flows, and liquid sprays, can be predicted efficiently by use of Euler-Lagrange models. In these models, grid-averaged equations for the continuous-phase flow field are

Adaptive hybrid mesh refinement for multiphysics applications

International Nuclear Information System (INIS)

Khamayseh, Ahmed; Almeida, Valmor de

2007-01-01

The accuracy and convergence of computational solutions of mesh-based methods is strongly dependent on the quality of the mesh used. We have developed methods for optimizing meshes that are comprised of elements of arbitrary polygonal and polyhedral type. We present in this research the development of r-h hybrid adaptive meshing technology tailored to application areas relevant to multi-physics modeling and simulation. Solution-based adaptation methods are used to reposition mesh nodes (r-adaptation) or to refine the mesh cells (h-adaptation) to minimize solution error. The numerical methods perform either the r-adaptive mesh optimization or the h-adaptive mesh refinement method on the initial isotropic or anisotropic meshes to equidistribute weighted geometric and/or solution error function. We have successfully introduced r-h adaptivity to a least-squares method with spherical harmonics basis functions for the solution of the spherical shallow atmosphere model used in climate modeling. In addition, application of this technology also covers a wide range of disciplines in computational sciences, most notably, time-dependent multi-physics, multi-scale modeling and simulation

A posteriori error analysis of multiscale operator decomposition methods for multiphysics models

International Nuclear Information System (INIS)

Estep, D; Carey, V; Tavener, S; Ginting, V; Wildey, T

2008-01-01

Multiphysics, multiscale models present significant challenges in computing accurate solutions and for estimating the error in information computed from numerical solutions. In this paper, we describe recent advances in extending the techniques of a posteriori error analysis to multiscale operator decomposition solution methods. While the particulars of the analysis vary considerably with the problem, several key ideas underlie a general approach being developed to treat operator decomposition multiscale methods. We explain these ideas in the context of three specific examples

Massive hybrid parallelism for fully implicit multiphysics

International Nuclear Information System (INIS)

Gaston, D. R.; Permann, C. J.; Andrs, D.; Peterson, J. W.

2013-01-01

As hardware advances continue to modify the supercomputing landscape, traditional scientific software development practices will become more outdated, ineffective, and inefficient. The process of rewriting/retooling existing software for new architectures is a Sisyphean task, and results in substantial hours of development time, effort, and money. Software libraries which provide an abstraction of the resources provided by such architectures are therefore essential if the computational engineering and science communities are to continue to flourish in this modern computing environment. The Multiphysics Object Oriented Simulation Environment (MOOSE) framework enables complex multiphysics analysis tools to be built rapidly by scientists, engineers, and domain specialists, while also allowing them to both take advantage of current HPC architectures, and efficiently prepare for future supercomputer designs. MOOSE employs a hybrid shared-memory and distributed-memory parallel model and provides a complete and consistent interface for creating multiphysics analysis tools. In this paper, a brief discussion of the mathematical algorithms underlying the framework and the internal object-oriented hybrid parallel design are given. Representative massively parallel results from several applications areas are presented, and a brief discussion of future areas of research for the framework are provided. (authors)

Massive hybrid parallelism for fully implicit multiphysics

Energy Technology Data Exchange (ETDEWEB)

Gaston, D. R.; Permann, C. J.; Andrs, D.; Peterson, J. W. [Idaho National Laboratory, 2525 N. Fremont Ave., Idaho Falls, ID 83415 (United States)

2013-07-01

As hardware advances continue to modify the supercomputing landscape, traditional scientific software development practices will become more outdated, ineffective, and inefficient. The process of rewriting/retooling existing software for new architectures is a Sisyphean task, and results in substantial hours of development time, effort, and money. Software libraries which provide an abstraction of the resources provided by such architectures are therefore essential if the computational engineering and science communities are to continue to flourish in this modern computing environment. The Multiphysics Object Oriented Simulation Environment (MOOSE) framework enables complex multiphysics analysis tools to be built rapidly by scientists, engineers, and domain specialists, while also allowing them to both take advantage of current HPC architectures, and efficiently prepare for future supercomputer designs. MOOSE employs a hybrid shared-memory and distributed-memory parallel model and provides a complete and consistent interface for creating multiphysics analysis tools. In this paper, a brief discussion of the mathematical algorithms underlying the framework and the internal object-oriented hybrid parallel design are given. Representative massively parallel results from several applications areas are presented, and a brief discussion of future areas of research for the framework are provided. (authors)

MASSIVE HYBRID PARALLELISM FOR FULLY IMPLICIT MULTIPHYSICS

Energy Technology Data Exchange (ETDEWEB)

Cody J. Permann; David Andrs; John W. Peterson; Derek R. Gaston

2013-05-01

As hardware advances continue to modify the supercomputing landscape, traditional scientific software development practices will become more outdated, ineffective, and inefficient. The process of rewriting/retooling existing software for new architectures is a Sisyphean task, and results in substantial hours of development time, effort, and money. Software libraries which provide an abstraction of the resources provided by such architectures are therefore essential if the computational engineering and science communities are to continue to flourish in this modern computing environment. The Multiphysics Object Oriented Simulation Environment (MOOSE) framework enables complex multiphysics analysis tools to be built rapidly by scientists, engineers, and domain specialists, while also allowing them to both take advantage of current HPC architectures, and efficiently prepare for future supercomputer designs. MOOSE employs a hybrid shared-memory and distributed-memory parallel model and provides a complete and consistent interface for creating multiphysics analysis tools. In this paper, a brief discussion of the mathematical algorithms underlying the framework and the internal object-oriented hybrid parallel design are given. Representative massively parallel results from several applications areas are presented, and a brief discussion of future areas of research for the framework are provided.

Capturing the complex behavior of hydraulic fracture stimulation through multi-physics modeling, field-based constraints, and model reduction

Science.gov (United States)

Johnson, S.; Chiaramonte, L.; Cruz, L.; Izadi, G.

2016-12-01

Advances in the accuracy and fidelity of numerical methods have significantly improved our understanding of coupled processes in unconventional reservoirs. However, such multi-physics models are typically characterized by many parameters and require exceptional computational resources to evaluate systems of practical importance, making these models difficult to use for field analyses or uncertainty quantification. One approach to remove these limitations is through targeted complexity reduction and field data constrained parameterization. For the latter, a variety of field data streams may be available to engineers and asset teams, including micro-seismicity from proximate sites, well logs, and 3D surveys, which can constrain possible states of the reservoir as well as the distributions of parameters. We describe one such workflow, using the Argos multi-physics code and requisite geomechanical analysis to parameterize the underlying models. We illustrate with a field study involving a constraint analysis of various field data and details of the numerical optimizations and model reduction to demonstrate how complex models can be applied to operation design in hydraulic fracturing operations, including selection of controllable completion and fluid injection design properties. The implication of this work is that numerical methods are mature and computationally tractable enough to enable complex engineering analysis and deterministic field estimates and to advance research into stochastic analyses for uncertainty quantification and value of information applications.

Well-posedness and stability characteristics of multi-phase models

International Nuclear Information System (INIS)

Ransom, V.H.; Trapp, J.A.

1984-01-01

The ill-posed characteristic associated with the basic two-fluid model for multi-phase flow is a natural consequence of the idealized physical model and the mean flow modeling approach. Two approaches are discussed whereby including added physics of the flow results in a well-posed system of partial differential equations. These models offer the possibility of improved accuracy and numerical efficiency compared to the numerical models used in the existing light water reactor safety analysis codes

Modified Invasion Percolation Models for Multiphase Processes

Energy Technology Data Exchange (ETDEWEB)

Karpyn, Zuleima [Pennsylvania State Univ., State College, PA (United States)

2015-01-31

This project extends current understanding and modeling capabilities of pore-scale multiphase flow physics in porous media. High-resolution X-ray computed tomography imaging experiments are used to investigate structural and surface properties of the medium that influence immiscible displacement. Using experimental and computational tools, we investigate the impact of wetting characteristics, as well as radial and axial loading conditions, on the development of percolation pathways, residual phase trapping and fluid-fluid interfacial areas.

A theory manual for multi-physics code coupling in LIME.

Energy Technology Data Exchange (ETDEWEB)

Belcourt, Noel; Bartlett, Roscoe Ainsworth; Pawlowski, Roger Patrick; Schmidt, Rodney Cannon; Hooper, Russell Warren

2011-03-01

The Lightweight Integrating Multi-physics Environment (LIME) is a software package for creating multi-physics simulation codes. Its primary application space is when computer codes are currently available to solve different parts of a multi-physics problem and now need to be coupled with other such codes. In this report we define a common domain language for discussing multi-physics coupling and describe the basic theory associated with multiphysics coupling algorithms that are to be supported in LIME. We provide an assessment of coupling techniques for both steady-state and time dependent coupled systems. Example couplings are also demonstrated.

Multiphysical model of heterogenous flow moving along а channel of variable cross-section

Directory of Open Access Journals (Sweden)

М. А. Васильева

2017-10-01

Full Text Available The article deals with the problem aimed at solving the fundamental problems of developing effective methods and tools for designing, controlling and managing the stream of fluid flowing in variable-section pipelines intended for the production of pumping equipment, medical devices and used in such areas of industry as mining, chemical, food production, etc. Execution of simulation modelling of flow motion according to the scheme of twisted paddle static mixer allows to estimate the efficiency of mixing by calculating the trajectory and velocities of the suspended particles going through the mixer, and also to estimate the pressure drop on the hydraulic flow resistance. The model examines the mixing of solids dissolved in a liquid at room temperature. To visualize the process of distributing the mixture particles over the cross-section and analyzing the mixing efficiency, the Poincaréplot module of the COMSOL Multiphysics software environment was used. For the first time, a multi-physical stream of heterogeneous flow model has been developed that describes in detail the physical state of the fluid at all points of the considered section at the initial time, takes into account the design parameters of the channel (orientation, dimensions, material, etc., specifies the laws of variation of the parameters at the boundaries of the calculated section in conditions of the wave change in the internal section of the working chamber-channel of the inductive peristaltic pumping unit under the influence of the energy of the magnetic field.

Scalable Adaptive Multilevel Solvers for Multiphysics Problems

Energy Technology Data Exchange (ETDEWEB)

Xu, Jinchao [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mathematics

2014-11-26

In this project, we carried out many studies on adaptive and parallel multilevel methods for numerical modeling for various applications, including Magnetohydrodynamics (MHD) and complex fluids. We have made significant efforts and advances in adaptive multilevel methods of the multiphysics problems: multigrid methods, adaptive finite element methods, and applications.

The simulation of multidimensional multiphase flows

International Nuclear Information System (INIS)

Lahey, Richard T.

2005-01-01

This paper presents an assessment of various models which can be used for the multidimensional simulation of multiphase flows, such as may occur in nuclear reactors. In particular, a model appropriate for the direct numerical simulation (DNS) of multiphase flows and a mechanistically based, three-dimensional, four-field, turbulent, two-fluid computational multiphase fluid dynamics (CMFD) model are discussed. A two-fluid bubbly flow model, which was derived using potential flow theory, can be extended to other flow regimes, but this will normally involve ensemble-averaging the results from direct numerical simulations (DNS) of various flow regimes to provide the detailed numerical data necessary for the development of flow-regime-specific interfacial and wall closure laws

Modeling of circulating nuclear fuels with Comsol Multiphysics

International Nuclear Information System (INIS)

Cammi, A.; Di Marcello, V.; Luzzi, L.

2007-01-01

This paper presents multi-physics modelling of circulating nuclear fuel in a simple geometry by means of COMSOL 3.3. Among the Circulating Fuel Reactors (CFR), the most promising is the Molten Salt Reactor (MSR). Physics of such circulating nuclear fuel requires five coupled equations of conservation laws: the momentum balance, the energy balance, the neutron balance and the precursors balance. In this complex field, represented by the coupling of thermal-hydrodynamics with neutronics, the highly non linear regime and the wide disparity of time scales, COMSOL was used to investigate the region of reactor that comprises only the flowing fluid, and a parametric study was performed by varying the size of the analyzed region and the inlet velocity of fluid. This study is sufficient to achieve a preliminary evaluation of the thermo-physical behaviour of the system and paves the way for further progress concerning a more complex and realistic MSR geometry. (authors)

Eliminating cubic terms in the pseudopotential lattice Boltzmann model for multiphase flow

Science.gov (United States)

Huang, Rongzong; Wu, Huiying; Adams, Nikolaus A.

2018-05-01

It is well recognized that there exist additional cubic terms of velocity in the lattice Boltzmann (LB) model based on the standard lattice. In this work, elimination of these cubic terms in the pseudopotential LB model for multiphase flow is investigated, where the force term and density gradient are considered. By retaining high-order (≥3 ) Hermite terms in the equilibrium distribution function and the discrete force term, as well as introducing correction terms in the LB equation, the additional cubic terms of velocity are entirely eliminated. With this technique, the computational simplicity of the pseudopotential LB model is well maintained. Numerical tests, including stationary and moving flat and circular interface problems, are carried out to show the effects of such cubic terms on the simulation of multiphase flow. It is found that the elimination of additional cubic terms is beneficial to reduce the numerical error, especially when the velocity is relatively large. Numerical results also suggest that these cubic terms mainly take effect in the interfacial region and that the density-gradient-related cubic terms are more important than the other cubic terms for multiphase flow.

Multiphase flow modeling of molten material-vapor-liquid mixtures in thermal nonequilibrium

International Nuclear Information System (INIS)

Park, Ik Kyu; Park, Goon Cherl; Bang, Kwang Hyun

2000-01-01

This paper presents a numerical model of multiphase flow of the mixtures of molten material-liquid-vapor, particularly in thermal nonequilibrium. It is a two-dimensional, transient, three-fluid model in Eulerian coordinates. The equations are solved numerically using the finite difference method that implicitly couples the rates of phase changes, momentum, and energy exchange to determine the pressure, density, and velocity fields. To examine the model's ability to predict an experimental data, calculations have been performed for tests of pouring hot particles and molten material into a water pool. The predictions show good agreement with the experimental data. It appears, however, that the interfacial heat transfer and breakup of molten material need improved models that can be applied to such high temperature, high pressure, multiphase flow conditions

Application of multiphase modelling for vortex occurrence in vertical pump intake - a review

International Nuclear Information System (INIS)

Samsudin, M L; Munisamy, K M; Thangaraju, S K

2015-01-01

Vortex formation within pump intake is one of common problems faced for power plant cooling water system. This phenomenon, categorised as surface and sub-surface vortices, can lead to several operational problems and increased maintenance costs. Physical model study was recommended from published guidelines but proved to be time and resource consuming. Hence, the use of Computational Fluid Dynamics (CFD) is an attractive alternative in managing the problem. At the early stage, flow analysis was conducted using single phase simulation and found to find good agreement with the observation from physical model study. With the development of computers, multiphase simulation found further enhancement in obtaining accurate results for representing air entrainment and sub-surface vortices which were earlier not well predicted from the single phase simulation.The purpose of this paper is to describe the application of multiphase modelling with CFD analysis for investigating vortex formation for a vertically inverted pump intake. In applying multiphase modelling, there ought to be a balance between the acceptable usage for computational time and resources and the degree of accuracy and realism in the results as expected from the analysis. (paper)

Application of multiphase modelling for vortex occurrence in vertical pump intake - a review

Science.gov (United States)

Samsudin, M. L.; Munisamy, K. M.; Thangaraju, S. K.

2015-09-01

Vortex formation within pump intake is one of common problems faced for power plant cooling water system. This phenomenon, categorised as surface and sub-surface vortices, can lead to several operational problems and increased maintenance costs. Physical model study was recommended from published guidelines but proved to be time and resource consuming. Hence, the use of Computational Fluid Dynamics (CFD) is an attractive alternative in managing the problem. At the early stage, flow analysis was conducted using single phase simulation and found to find good agreement with the observation from physical model study. With the development of computers, multiphase simulation found further enhancement in obtaining accurate results for representing air entrainment and sub-surface vortices which were earlier not well predicted from the single phase simulation. The purpose of this paper is to describe the application of multiphase modelling with CFD analysis for investigating vortex formation for a vertically inverted pump intake. In applying multiphase modelling, there ought to be a balance between the acceptable usage for computational time and resources and the degree of accuracy and realism in the results as expected from the analysis.

Multi-phase flow modeling of soil contamination and soil remediation

NARCIS (Netherlands)

Dijke, van M.I.J.

1997-01-01

In this thesis multi-phase flow models are used to study the flow behavior of liquid contaminants in aquifers and of gases that are injected below the groundwater table for remediation purposes. Considered problems are redistribution of a lens of light nonaqueous phase

Implementation of geomechanical models for engineered clay barriers in multi-physic partial differential equation solvers

International Nuclear Information System (INIS)

Navarro, V.; Alonso, J.; Asensio, L.; Yustres, A.; Pintado, X.

2012-01-01

Document available in extended abstract form only. The use of numerical methods, especially the Finite Element Method (FEM), for solving boundary problems in Unsaturated Soil Mechanics has experienced significant progress. Several codes, both built mainly for research purposes and commercial software, are now available. In the last years, Multi-physic Partial Differentiation Equation Solvers (MPDES) have turned out to be an interesting proposal. In this family of solvers, the user defines the governing equations and the behaviour models, generally using a computer algebra environment. The code automatically assembles and solves the equation systems, saving the user having to redefine the structures of memory storage or to implement solver algorithms. The user can focus on the definition of the physics of the problem, while it is possible to couple virtually any physical or chemical process that can be described by a PDE. This can be done, for instance, in COMSOL Multiphysics (CM). Nonetheless, the versatility of CM is compromised by the impossibility to implement models with variables defined by implicit functions. Elasto-plastic models involve an implicit coupling among stress increments, plastic strains and plastic variables increments. For this reason, they cannot be implemented in CM in a straightforward way. This means a very relevant limitation for the use of this tool in the analysis of geomechanical boundary value problems. In this work, a strategy to overcome this problem using the multi-physics concept is presented. A mixed method is proposed, considering the constitutive stresses, the pre-consolidation pressure and the plastic variables as main unknowns of the model. Mixed methods usually present stability problems. However, the algorithmics present in CM include several numerical strategies to minimise this kind of problems. Besides, CM is based on the application of the FEM with Lagrange multipliers, an approach that significantly contributes stability

Multiphysics Model of Palladium Hydride Isotope Exchange Accounting for Higher Dimensionality

Energy Technology Data Exchange (ETDEWEB)

Gharagozloo, Patricia E.; Eliassi, Mehdi; Bon, Bradley Luis

2015-03-01

This report summarizes computational model developm ent and simulations results for a series of isotope exchange dynamics experiments i ncluding long and thin isothermal beds similar to the Foltz and Melius beds and a lar ger non-isothermal experiment on the NENG7 test bed. The multiphysics 2D axi-symmetr ic model simulates the temperature and pressure dependent exchange reactio n kinetics, pressure and isotope dependent stoichiometry, heat generation from the r eaction, reacting gas flow through porous media, and non-uniformities in the bed perme ability. The new model is now able to replicate the curved reaction front and asy mmetry of the exit gas mass fractions over time. The improved understanding of the exchange process and its dependence on the non-uniform bed properties and te mperatures in these larger systems is critical to the future design of such sy stems.

Modelling and simulation of multi-phase effects on X-ray elasticity constants

CERN Document Server

Freour, S; Guillen, R; François, M X

2003-01-01

This paper deals with the calculation of X-ray Elasticity Constants (XEC) of phases embedded in multi-phase polycrystals. A three scales (macroscopic, pseudo-macroscopic, mesoscopic) model based on the classical self-consistent formalism is developed in order to analyse multi-phase effects on XEC values. Simulations are performed for cubic or hexagonal crystallographic structure phases embedded in several two-phases materials. In fact, it is demonstrated that XEC vary with the macroscopic stiffness of the whole polycrystal. In consequence, the constants of one particular phase depend on the elastic behaviour and the volume fraction of all the phases constituting the material. Now, XEC play a leading role in pseudo-macroscopic stresses determination by X-Ray Diffraction (XRD) methods. In this work, a quantitative analysis of the multi-phase effects on stresses determination by XRD methods was performed. Numerical results will be compared and discussed. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

On the extension of multi-phase models to sub-residual saturations

International Nuclear Information System (INIS)

Lingineni, S.; Chen, Y.T.; Boehm, R.F.

1995-01-01

This paper focuses on the limitations of applying multi-phase flow and transport models to simulate the hydrothermal processes occurring when the liquid saturation falls below residual levels. A typical scenario of a heat-generating high-level waste package emplaced in a backfilled drift of a waste repository is presented. The hydrothermal conditions in the vicinity of the waste package as well as in the far-field are determined using multi-phase, non-isothermal codes such as TOUGH2 and FEHM. As the waste package temperature increases, heat-pipe effects are created and water is driven away from the package into colder regions where it condenses. The variations in the liquid saturations close to the waste package are determined using these models with extended capillary pressure-saturations relationships to sub-residual regime. The predictions indicate even at elevated temperatures, waste package surroundings are not completely dry. However, if transport based modeling is used to represent liquid saturation variations in the sub-residual regime, then complete dry conditions are predicted within the backfill for extended periods of time. The relative humidity conditions near the waste package are also found to be sensitive to the representation of capillary pressure-saturation relationship used for sub-residual regime. An experimental investigation is carried out to study the variations in liquid saturations and relative humidity conditions in sub-residual regimes. Experimental results indicated that extended multi-phase models without interphase transport can not predict dry-out conditions and the simulations underpredict the humidity conditions near the waste package

Quench Simulation of Superconducting Magnets with Commercial Multiphysics Software

CERN Document Server

AUTHOR|(SzGeCERN)751171; Auchmann, Bernhard; Jarkko, Niiranen; Maciejewski, Michal

The simulation of quenches in superconducting magnets is a multiphysics problem of highest complexity. Operated at 1.9 K above absolute zero, the material properties of superconductors and superfluid helium vary by several orders of magnitude over a range of only 10 K. The heat transfer from metal to helium goes through different transfer and boiling regimes as a function of temperature, heat flux, and transferred energy. Electrical, magnetic, thermal, and fluid dynamic effects are intimately coupled, yet live on vastly different time and spatial scales. While the physical models may be the same in all cases, it is an open debate whether the user should opt for commercial multiphysics software like ANSYS or COMSOL, write customized models based on general purpose network solvers like SPICE, or implement the physics models and numerical solvers entirely in custom software like the QP3, THEA, and ROXIE codes currently in use at the European Organisation for Nuclear Research (CERN). Each approach has its strengt...

Methods for compressible multiphase flows and their applications

Science.gov (United States)

Kim, H.; Choe, Y.; Kim, H.; Min, D.; Kim, C.

2018-06-01

This paper presents an efficient and robust numerical framework to deal with multiphase real-fluid flows and their broad spectrum of engineering applications. A homogeneous mixture model incorporated with a real-fluid equation of state and a phase change model is considered to calculate complex multiphase problems. As robust and accurate numerical methods to handle multiphase shocks and phase interfaces over a wide range of flow speeds, the AUSMPW+_N and RoeM_N schemes with a system preconditioning method are presented. These methods are assessed by extensive validation problems with various types of equation of state and phase change models. Representative realistic multiphase phenomena, including the flow inside a thermal vapor compressor, pressurization in a cryogenic tank, and unsteady cavitating flow around a wedge, are then investigated as application problems. With appropriate physical modeling followed by robust and accurate numerical treatments, compressible multiphase flow physics such as phase changes, shock discontinuities, and their interactions are well captured, confirming the suitability of the proposed numerical framework to wide engineering applications.

3D multiphysics modeling of superconducting cavities with a massively parallel simulation suite

Directory of Open Access Journals (Sweden)

Oleksiy Kononenko

2017-10-01

Full Text Available Radiofrequency cavities based on superconducting technology are widely used in particle accelerators for various applications. The cavities usually have high quality factors and hence narrow bandwidths, so the field stability is sensitive to detuning from the Lorentz force and external loads, including vibrations and helium pressure variations. If not properly controlled, the detuning can result in a serious performance degradation of a superconducting accelerator, so an understanding of the underlying detuning mechanisms can be very helpful. Recent advances in the simulation suite ace3p have enabled realistic multiphysics characterization of such complex accelerator systems on supercomputers. In this paper, we present the new capabilities in ace3p for large-scale 3D multiphysics modeling of superconducting cavities, in particular, a parallel eigensolver for determining mechanical resonances, a parallel harmonic response solver to calculate the response of a cavity to external vibrations, and a numerical procedure to decompose mechanical loads, such as from the Lorentz force or piezoactuators, into the corresponding mechanical modes. These capabilities have been used to do an extensive rf-mechanical analysis of dressed TESLA-type superconducting cavities. The simulation results and their implications for the operational stability of the Linac Coherent Light Source-II are discussed.

Microstructural modelling of nuclear graphite using multi-phase models

International Nuclear Information System (INIS)

Berre, C.; Fok, S.L.; Marsden, B.J.; Mummery, P.M.; Marrow, T.J.; Neighbour, G.B.

2008-01-01

This paper presents a new modelling technique using three-dimensional multi-phase finite element models in which meshes representing the microstructure of thermally oxidised nuclear graphite were generated from X-ray micro-tomography images. The density of the material was related to the image greyscale using Beer-Lambert's law, and multiple phases could thus be defined. The local elastic and non-linear properties of each phase were defined as a function of density and changes in Young's modulus, tensile and compressive strength with thermal oxidation were calculated. Numerical predictions compared well with experimental data and with other numerical results obtained using two-phase models. These models were found to be more representative of the actual microstructure of the scanned material than two-phase models and, possibly because of pore closure occurring during compression, compressive tests were also predicted to be less sensitive to the microstructure geometry than tensile tests

Multiphysical Simulation of PT-CT Contact with Outer Boundary Condition

Energy Technology Data Exchange (ETDEWEB)

Chang, Se-Myong [Kunsan National Univ., Gunsan (Korea, Republic of); Kim, Hyoung Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

The present study is about preliminary calculation results for these ICSP activity works, where the COMSOL Multiphysics code is used to simulate plastic deformation of a pressure tube as a result of the interaction of stress and temperature. It is shown that the thermal stress model of COMSOL is compatible to simulate the multiple heat transfers (including the radiation heat transfer and heat conduction) and stress strain in the simplified 2-D problem. The benchmark test result for radiation heat transfer is in good agreement with the analytical solution for the concentric configuration of PT(pressure tube) and CT(calandria tube). In this paper, the authors did an open computation of these multi-physical phenomena by changing the outer boundary condition of CT according to the experimental result of ICSP. A series of simulation has been done based on the benchmark test proposed by IAEA/ICSP. The unsteady multi-physics was treated some numerical models with COMSOL. The comparison with CATHENA code is verified as a good agreement as we increase the accuracy of numerical method, Gaussian quadrature. The open computation for the validation of this numerical code is still on-going, and the temperature inside and outside the PT shows a very good agreement.

Multiphysical Simulation of PT-CT Contact with Outer Boundary Condition

International Nuclear Information System (INIS)

Chang, Se-Myong; Kim, Hyoung Tae

2016-01-01

The present study is about preliminary calculation results for these ICSP activity works, where the COMSOL Multiphysics code is used to simulate plastic deformation of a pressure tube as a result of the interaction of stress and temperature. It is shown that the thermal stress model of COMSOL is compatible to simulate the multiple heat transfers (including the radiation heat transfer and heat conduction) and stress strain in the simplified 2-D problem. The benchmark test result for radiation heat transfer is in good agreement with the analytical solution for the concentric configuration of PT(pressure tube) and CT(calandria tube). In this paper, the authors did an open computation of these multi-physical phenomena by changing the outer boundary condition of CT according to the experimental result of ICSP. A series of simulation has been done based on the benchmark test proposed by IAEA/ICSP. The unsteady multi-physics was treated some numerical models with COMSOL. The comparison with CATHENA code is verified as a good agreement as we increase the accuracy of numerical method, Gaussian quadrature. The open computation for the validation of this numerical code is still on-going, and the temperature inside and outside the PT shows a very good agreement

Parallel multiphysics algorithms and software for computational nuclear engineering

International Nuclear Information System (INIS)

Gaston, D; Hansen, G; Kadioglu, S; Knoll, D A; Newman, C; Park, H; Permann, C; Taitano, W

2009-01-01

There is a growing trend in nuclear reactor simulation to consider multiphysics problems. This can be seen in reactor analysis where analysts are interested in coupled flow, heat transfer and neutronics, and in fuel performance simulation where analysts are interested in thermomechanics with contact coupled to species transport and chemistry. These more ambitious simulations usually motivate some level of parallel computing. Many of the coupling efforts to date utilize simple code coupling or first-order operator splitting, often referred to as loose coupling. While these approaches can produce answers, they usually leave questions of accuracy and stability unanswered. Additionally, the different physics often reside on separate grids which are coupled via simple interpolation, again leaving open questions of stability and accuracy. Utilizing state of the art mathematics and software development techniques we are deploying next generation tools for nuclear engineering applications. The Jacobian-free Newton-Krylov (JFNK) method combined with physics-based preconditioning provide the underlying mathematical structure for our tools. JFNK is understood to be a modern multiphysics algorithm, but we are also utilizing its unique properties as a scale bridging algorithm. To facilitate rapid development of multiphysics applications we have developed the Multiphysics Object-Oriented Simulation Environment (MOOSE). Examples from two MOOSE-based applications: PRONGHORN, our multiphysics gas cooled reactor simulation tool and BISON, our multiphysics, multiscale fuel performance simulation tool will be presented.

Multi-phase physicochemical modeling of soil-cementitious material interaction

International Nuclear Information System (INIS)

Nakarai, Kenichiro; Ishida, Tetsuya; Maekawa, Koichi

2005-01-01

Multi-phase physicochemical modeling based on thermodynamic approach is studied on gel and capillary pores of nano-micrometers and large voids of micro-millimeters among soil foundation. A computational method about transportation of moisture and ions in pore structure for simulating concrete performance was extended for predicting time-dependent material properties of cemented soil. The proposed model was verified with experimental results of cement hydration, change of relative humidity and leaching of calcium ion from cement hydrate to underground water. (author)

Infrastructure for Multiphysics Software Integration in High Performance Computing-Aided Science and Engineering

Energy Technology Data Exchange (ETDEWEB)

Campbell, Michael T. [Illinois Rocstar LLC, Champaign, IL (United States); Safdari, Masoud [Illinois Rocstar LLC, Champaign, IL (United States); Kress, Jessica E. [Illinois Rocstar LLC, Champaign, IL (United States); Anderson, Michael J. [Illinois Rocstar LLC, Champaign, IL (United States); Horvath, Samantha [Illinois Rocstar LLC, Champaign, IL (United States); Brandyberry, Mark D. [Illinois Rocstar LLC, Champaign, IL (United States); Kim, Woohyun [Illinois Rocstar LLC, Champaign, IL (United States); Sarwal, Neil [Illinois Rocstar LLC, Champaign, IL (United States); Weisberg, Brian [Illinois Rocstar LLC, Champaign, IL (United States)

2016-10-15

The project described in this report constructed and exercised an innovative multiphysics coupling toolkit called the Illinois Rocstar MultiPhysics Application Coupling Toolkit (IMPACT). IMPACT is an open source, flexible, natively parallel infrastructure for coupling multiple uniphysics simulation codes into multiphysics computational systems. IMPACT works with codes written in several high-performance-computing (HPC) programming languages, and is designed from the beginning for HPC multiphysics code development. It is designed to be minimally invasive to the individual physics codes being integrated, and has few requirements on those physics codes for integration. The goal of IMPACT is to provide the support needed to enable coupling existing tools together in unique and innovative ways to produce powerful new multiphysics technologies without extensive modification and rewrite of the physics packages being integrated. There are three major outcomes from this project: 1) construction, testing, application, and open-source release of the IMPACT infrastructure, 2) production of example open-source multiphysics tools using IMPACT, and 3) identification and engagement of interested organizations in the tools and applications resulting from the project. This last outcome represents the incipient development of a user community and application echosystem being built using IMPACT. Multiphysics coupling standardization can only come from organizations working together to define needs and processes that span the space of necessary multiphysics outcomes, which Illinois Rocstar plans to continue driving toward. The IMPACT system, including source code, documentation, and test problems are all now available through the public gitHUB.org system to anyone interested in multiphysics code coupling. Many of the basic documents explaining use and architecture of IMPACT are also attached as appendices to this document. Online HTML documentation is available through the gitHUB site

Probabilistic Design and Management of Sustainable Concrete Infrastructure Using Multi-Physics Service Life Models

DEFF Research Database (Denmark)

Lepech, Michael; Geiker, Mette; Michel, Alexander

This paper looks to address the grand challenge of integrating construction materials engineering research within a multi-scale, inter-disciplinary research and management framework for sustainable concrete infrastructure. The ultimate goal is to drive sustainability-focused innovation and adoption...... cycles in the broader architecture, engineering, construction (AEC) industry. Specifically, a probabilistic design framework for sustainable concrete infrastructure and a multi-physics service life model for reinforced concrete are presented as important points of integration for innovation between...... design, consists of concrete service life models and life cycle assessment (LCA) models. Both types of models (service life and LCA) are formulated stochastically so that the service life and time(s) to repair, as well as total sustainability impact, are described by a probability distribution. A central...

Two-Fluid Models for Simulating Dispersed Multiphase Flows-A Review

Directory of Open Access Journals (Sweden)

L.X. Zhou

2009-01-01

Full Text Available The development of two-fluid models for simulating dispersed multiphase flows (gas-particle, gas-droplet, bubble-liquid, liquid-particle flows by the present author within the last 20 years is systematically reviewed. The two-fluid models based on Reynolds expansion, time averaging and mass-weighed averaging, and also PDF transport equations are described. Different versions of two-phase turbulence models, including the unified second-order moment (USM and k-ε-kp models, the DSM-PDF model, the SOM-MC model, the nonlinear k-e-kp model, and the USM-Θ model for dense gas-particle flows and their application and experimental validation are discussed.

Multiphase flow in wells and pipelines

International Nuclear Information System (INIS)

Sharma, M.P.; Rohatgi, U.S.

1992-01-01

This conference focuses primarily on multi-phase flow modeling and calculation methods for oil and gas although two papers focus more on the fluid mechanics of fluidized beds. Papers include theoretical, numerical modeling, experimental investigation, and state-of-the-art review aspects of multiphase flow. The theme of the symposium being general, the papers reflect generality of gas-liquid, liquid-solid, and gas solid flows. One paper deals with nuclear reactor safety as it relates to fluid flow through the reactor

FEM Modeling of Crack Propagation in a Model Multiphase Alloy

Institute of Scientific and Technical Information of China (English)

Lihe QIAN; Seishi NISHIDO; Hiroyuki TODA; Tosliro KOBAYASHI

2006-01-01

In this paper, several widely applied fracture criteria were first numerically examined and the crack-tip-region Jintegral criterion was confirmed to be more applicable to predict fracture angle in an elastic-plastic multiphase material. Then, the crack propagation in an idealized dendritic two-phase Al-7%Si alloy was modeled using an elastic-plastic finite element method. The variation of crack growth driving force with crack extension was also demonstrated. It is found that the crack path is significantly influenced by the presence of α-phase near the crack tip, and the crack growth driving force varies drastically from place to place. Lastly, the simulated fracture path in the two-phase model alloy was compared with the experimentally observed fracture path.

Multiphysics simulation electromechanical system applications and optimization

CERN Document Server

Dede, Ercan M; Nomura, Tsuyoshi

2014-01-01

This book highlights a unique combination of numerical tools and strategies for handling the challenges of multiphysics simulation, with a specific focus on electromechanical systems as the target application. Features: introduces the concept of design via simulation, along with the role of multiphysics simulation in today's engineering environment; discusses the importance of structural optimization techniques in the design and development of electromechanical systems; provides an overview of the physics commonly involved with electromechanical systems for applications such as electronics, ma

EDITORIAL: Measurement techniques for multiphase flows Measurement techniques for multiphase flows

Science.gov (United States)

Okamoto, Koji; Murai, Yuichi

2009-11-01

Research on multiphase flows is very important for industrial applications, including power stations, vehicles, engines, food processing and so on. Multiphase flows originally have nonlinear features because of multiphase systems. The interaction between the phases plays a very interesting role in the flows. The nonlinear interaction causes the multiphase flows to be very complicated. Therefore techniques for measuring multiphase flows are very useful in helping to understand the nonlinear phenomena. The state-of-the-art measurement techniques were presented and discussed at the sixth International Symposium on Measurement Techniques for Multiphase Flows (ISMTMF2008) held in Okinawa, Japan, on 15-17 December 2008. This special feature of Measurement Science and Technology includes selected papers from ISMTMF2008. Okinawa has a long history as the Ryukyus Kingdom. China, Japan and many western Pacific countries have had cultural and economic exchanges through Okinawa for over 1000 years. Much technical and scientific information was exchanged at the symposium in Okinawa. The proceedings of ISMTMF2008 apart from these special featured papers were published in Journal of Physics: Conference Series vol. 147 (2009). We would like to express special thanks to all the contributors to the symposium and this special feature. This special feature will be a milestone in measurement techniques for multiphase flows.

Multiphysics simulation of thermal phenomena in direct laser metal powder deposition

CSIR Research Space (South Africa)

Pityana, SL

2016-11-01

Full Text Available presents on two dimensional multi-physics models to describe the physical mechanism of heat transfer, melting and solidification that take place during and post laser-powder interaction. The simulated transient temperature profile, the geometrical features...

Design and multi-physics optimization of rotary MRF brakes

Science.gov (United States)

Topcu, Okan; Taşcıoğlu, Yiğit; Konukseven, Erhan İlhan

2018-03-01

Particle swarm optimization (PSO) is a popular method to solve the optimization problems. However, calculations for each particle will be excessive when the number of particles and complexity of the problem increases. As a result, the execution speed will be too slow to achieve the optimized solution. Thus, this paper proposes an automated design and optimization method for rotary MRF brakes and similar multi-physics problems. A modified PSO algorithm is developed for solving multi-physics engineering optimization problems. The difference between the proposed method and the conventional PSO is to split up the original single population into several subpopulations according to the division of labor. The distribution of tasks and the transfer of information to the next party have been inspired by behaviors of a hunting party. Simulation results show that the proposed modified PSO algorithm can overcome the problem of heavy computational burden of multi-physics problems while improving the accuracy. Wire type, MR fluid type, magnetic core material, and ideal current inputs have been determined by the optimization process. To the best of the authors' knowledge, this multi-physics approach is novel for optimizing rotary MRF brakes and the developed PSO algorithm is capable of solving other multi-physics engineering optimization problems. The proposed method has showed both better performance compared to the conventional PSO and also has provided small, lightweight, high impedance rotary MRF brake designs.

Numerical modeling of experimental observations on gas formation and multi-phase flow of carbon dioxide in subsurface formations

Science.gov (United States)

Pawar, R.; Dash, Z.; Sakaki, T.; Plampin, M. R.; Lassen, R. N.; Illangasekare, T. H.; Zyvoloski, G.

2011-12-01

One of the concerns related to geologic CO2 sequestration is potential leakage of CO2 and its subsequent migration to shallow groundwater resources leading to geochemical impacts. Developing approaches to monitor CO2 migration in shallow aquifer and mitigate leakage impacts will require improving our understanding of gas phase formation and multi-phase flow subsequent to CO2 leakage in shallow aquifers. We are utilizing an integrated approach combining laboratory experiments and numerical simulations to characterize the multi-phase flow of CO2 in shallow aquifers. The laboratory experiments involve a series of highly controlled experiments in which CO2 dissolved water is injected in homogeneous and heterogeneous soil columns and tanks. The experimental results are used to study the effects of soil properties, temperature, pressure gradients and heterogeneities on gas formation and migration. We utilize the Finite Element Heat and Mass (FEHM) simulator (Zyvoloski et al, 2010) to numerically model the experimental results. The numerical models capture the physics of CO2 exsolution, multi-phase fluid flow as well as sand heterogeneity. Experimental observations of pressure, temperature and gas saturations are used to develop and constrain conceptual models for CO2 gas-phase formation and multi-phase CO2 flow in porous media. This talk will provide details of development of conceptual models based on experimental observation, development of numerical models for laboratory experiments and modelling results.

Multi-Physics Modelling of Fault Mechanics Using REDBACK: A Parallel Open-Source Simulator for Tightly Coupled Problems

Science.gov (United States)

Poulet, Thomas; Paesold, Martin; Veveakis, Manolis

2017-03-01

Faults play a major role in many economically and environmentally important geological systems, ranging from impermeable seals in petroleum reservoirs to fluid pathways in ore-forming hydrothermal systems. Their behavior is therefore widely studied and fault mechanics is particularly focused on the mechanisms explaining their transient evolution. Single faults can change in time from seals to open channels as they become seismically active and various models have recently been presented to explain the driving forces responsible for such transitions. A model of particular interest is the multi-physics oscillator of Alevizos et al. (J Geophys Res Solid Earth 119(6), 4558-4582, 2014) which extends the traditional rate and state friction approach to rate and temperature-dependent ductile rocks, and has been successfully applied to explain spatial features of exposed thrusts as well as temporal evolutions of current subduction zones. In this contribution we implement that model in REDBACK, a parallel open-source multi-physics simulator developed to solve such geological instabilities in three dimensions. The resolution of the underlying system of equations in a tightly coupled manner allows REDBACK to capture appropriately the various theoretical regimes of the system, including the periodic and non-periodic instabilities. REDBACK can then be used to simulate the drastic permeability evolution in time of such systems, where nominally impermeable faults can sporadically become fluid pathways, with permeability increases of several orders of magnitude.

Modeling compressible multiphase flows with dispersed particles in both dense and dilute regimes

Science.gov (United States)

McGrath, T.; St. Clair, J.; Balachandar, S.

2018-05-01

Many important explosives and energetics applications involve multiphase formulations employing dispersed particles. While considerable progress has been made toward developing mathematical models and computational methodologies for these flows, significant challenges remain. In this work, we apply a mathematical model for compressible multiphase flows with dispersed particles to existing shock and explosive dispersal problems from the literature. The model is cast in an Eulerian framework, treats all phases as compressible, is hyperbolic, and satisfies the second law of thermodynamics. It directly applies the continuous-phase pressure gradient as a forcing function for particle acceleration and thereby retains relaxed characteristics for the dispersed particle phase that remove the constituent material sound velocity from the eigenvalues. This is consistent with the expected characteristics of dispersed particle phases and can significantly improve the stable time-step size for explicit methods. The model is applied to test cases involving the shock and explosive dispersal of solid particles and compared to data from the literature. Computed results compare well with experimental measurements, providing confidence in the model and computational methods applied.

Curing of Thick Thermoset Composite Laminates: Multiphysics Modeling and Experiments

Science.gov (United States)

Anandan, S.; Dhaliwal, G. S.; Huo, Z.; Chandrashekhara, K.; Apetre, N.; Iyyer, N.

2017-11-01

Fiber reinforced polymer composites are used in high-performance aerospace applications as they are resistant to fatigue, corrosion free and possess high specific strength. The mechanical properties of these composite components depend on the degree of cure and residual stresses developed during the curing process. While these parameters are difficult to determine experimentally in large and complex parts, they can be simulated using numerical models in a cost-effective manner. These simulations can be used to develop cure cycles and change processing parameters to obtain high-quality parts. In the current work, a numerical model was built in Comsol MultiPhysics to simulate the cure behavior of a carbon/epoxy prepreg system (IM7/Cycom 5320-1). A thermal spike was observed in thick laminates when the recommended cure cycle was used. The cure cycle was modified to reduce the thermal spike and maintain the degree of cure at the laminate center. A parametric study was performed to evaluate the effect of air flow in the oven, post cure cycles and cure temperatures on the thermal spike and the resultant degree of cure in the laminate.

Multiphysics Modeling of an Annular Linear Induction Pump With Applications to Space Nuclear Power Systems

Science.gov (United States)

Kilbane, J.; Polzin, K. A.

2014-01-01

An annular linear induction pump (ALIP) that could be used for circulating liquid-metal coolant in a fission surface power reactor system is modeled in the present work using the computational COMSOL Multiphysics package. The pump is modeled using a two-dimensional, axisymmetric geometry and solved under conditions similar to those used during experimental pump testing. Real, nonlinear, temperature-dependent material properties can be incorporated into the model for both the electrically-conducting working fluid in the pump (NaK-78) and structural components of the pump. The intricate three-phase coil configuration of the pump is implemented in the model to produce an axially-traveling magnetic wave that is qualitatively similar to the measured magnetic wave. The model qualitatively captures the expected feature of a peak in efficiency as a function of flow rate.

Fully coupled multiphysics modeling of enhanced thermal conductivity UO{sub 2}–BeO fuel performance in a light water reactor

Energy Technology Data Exchange (ETDEWEB)

Liu, R. [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong (China); Zhou, W., E-mail: wenzzhou@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong (China); Shen, P. [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong (China); Prudil, A. [Fuel and Fuel Channel Safety Branch, Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Chan, P.K. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario (Canada)

2015-12-15

Highlights: • LWR fuel performance modeling capability developed. • Fully coupled multiphysics studies for enhanced thermal conductivity UO{sub 2}–BeO fuel. • UO{sub 2}–BeO fuel decreases fuel temperature and lessens thermal stresses. • UO{sub 2}–BeO fuel facilitates a reduction in PCMI. • Reactor safety can be improved for UO{sub 2}–BeO fuel. - Abstract: Commercial light water reactor fuel UO{sub 2} has a low thermal conductivity that leads to the development of a large temperature gradient across the fuel pellet, limiting the reactor operational performance due to the effects that include thermal stresses causing pellet cladding interaction and the release of fission product gases. This study presents the development of a modeling and simulation for enhanced thermal conductivity UO{sub 2}–BeO fuel behavior in a light water reactor, using self-defined multiple physics models fully coupled based on the framework of COMSOL Multiphysics. Almost all the related physical models are considered, including heat generation and conduction, species diffusion, thermomechanics (thermal expansion, elastic strain, densification, and fission product swelling strain), grain growth, fission gas production and release, gap heat transfer, mechanical contact, gap/plenum pressure with plenum volume, cladding thermal and irradiation creep and oxidation. All the phenomenal models and materials properties are implemented into COMSOL Multiphysics finite-element platform with a 2D axisymmetric geometry of a fuel pellet and cladding. UO{sub 2}–BeO enhanced thermal conductivity nuclear fuel would decrease fuel temperatures and facilitate a reduction in pellet cladding interaction from our simulation results through lessening thermal stresses that result in fuel cracking, relocation, and swelling, so that the safety of the reactor would be improved.

Numerical modelling of diesel spray using the Eulerian multiphase approach

International Nuclear Information System (INIS)

Vujanović, Milan; Petranović, Zvonimir; Edelbauer, Wilfried; Baleta, Jakov; Duić, Neven

2015-01-01

Highlights: • Numerical model for fuel disintegration was presented. • Fuel liquid and vapour were calculated. • Good agreement with experimental data was shown for various combinations of injection and chamber pressure. - Abstract: This research investigates high pressure diesel fuel injection into the combustion chamber by performing computational simulations using the Euler–Eulerian multiphase approach. Six diesel-like conditions were simulated for which the liquid fuel jet was injected into a pressurised inert environment (100% N 2 ) through a 205 μm nozzle hole. The analysis was focused on the liquid jet and vapour penetration, describing spatial and temporal spray evolution. For this purpose, an Eulerian multiphase model was implemented, variations of the sub-model coefficients were performed, and their impact on the spray formation was investigated. The final set of sub-model coefficients was applied to all operating points. Several simulations of high pressure diesel injections (50, 80, and 120 MPa) combined with different chamber pressures (5.4 and 7.2 MPa) were carried out and results were compared to the experimental data. The predicted results share a similar spray cloud shape for all conditions with the different vapour and liquid penetration length. The liquid penetration is shortened with the increase in chamber pressure, whilst the vapour penetration is more pronounced by elevating the injection pressure. Finally, the results showed good agreement when compared to the measured data, and yielded the correct trends for both the liquid and vapour penetrations under different operating conditions

A multi-phase ferrofluid flow model with equation of state for thermomagnetic pumping and heat transfer

Energy Technology Data Exchange (ETDEWEB)

Aursand, Eskil, E-mail: eskil.aursand@sintef.no; Gjennestad, Magnus Aa.; Yngve Lervåg, Karl; Lund, Halvor

2016-03-15

A one-dimensional multi-phase flow model for thermomagnetically pumped ferrofluid with heat transfer is proposed. The thermodynamic model is a combination of a simplified particle model and thermodynamic equations of state for the base fluid. The magnetization model is based on statistical mechanics, taking into account non-uniform particle size distributions. An implementation of the proposed model is validated against experiments from the literature, and found to give good predictions for the thermomagnetic pumping performance. However, the results reveal a very large sensitivity to uncertainties in heat transfer coefficient predictions. - Highlights: • A multi-phase flow model for thermomagnetically pumped ferrofluid is proposed. • An implementation is validated against experiments from the literature. • Predicted thermomagnetic pumping effect agrees with experiments. • However, a very large sensitivity to heat transfer coefficient is revealed.

Comprehensive preclinical evaluation of a multi-physics model of liver tumor radiofrequency ablation.

Science.gov (United States)

Audigier, Chloé; Mansi, Tommaso; Delingette, Hervé; Rapaka, Saikiran; Passerini, Tiziano; Mihalef, Viorel; Jolly, Marie-Pierre; Pop, Raoul; Diana, Michele; Soler, Luc; Kamen, Ali; Comaniciu, Dorin; Ayache, Nicholas

2017-09-01

We aim at developing a framework for the validation of a subject-specific multi-physics model of liver tumor radiofrequency ablation (RFA). The RFA computation becomes subject specific after several levels of personalization: geometrical and biophysical (hemodynamics, heat transfer and an extended cellular necrosis model). We present a comprehensive experimental setup combining multimodal, pre- and postoperative anatomical and functional images, as well as the interventional monitoring of intra-operative signals: the temperature and delivered power. To exploit this dataset, an efficient processing pipeline is introduced, which copes with image noise, variable resolution and anisotropy. The validation study includes twelve ablations from five healthy pig livers: a mean point-to-mesh error between predicted and actual ablation extent of 5.3 ± 3.6 mm is achieved. This enables an end-to-end preclinical validation framework that considers the available dataset.

Nonequilibrium Physics and Phase-Field Modeling of Multiphase Flow in Porous Media

Energy Technology Data Exchange (ETDEWEB)

Juanes, Ruben [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2016-09-01

The overarching goal of this project was to develop a new continuum theory of multiphase flow in porous media. The theory follows a phase-field modeling approach, and therefore has a sound thermodynamical basis. It is a phenomenological theory in the sense that its formulation is driven by macroscopic phenomena, such as viscous instabilities during multifluid displacement. The research agenda was organized around a set of hypothesis on hitherto unexplained behavior of multiphase flow. All these hypothesis are nontrivial, and testable. Indeed, a central aspect of the project was testing each hypothesis by means of carefully-designed laboratory experiments, therefore probing the validity of the proposed theory. The proposed research places an emphasis on the fundamentals of flow physics, but is motivated by important energy-driven applications in earth sciences, as well as microfluidic technology.

A Coupled Field Multiphysics Modeling Approach to Investigate RF MEMS Switch Failure Modes under Various Operational Conditions

Directory of Open Access Journals (Sweden)

Khaled Sadek

2009-10-01

Full Text Available In this paper, the reliability of capacitive shunt RF MEMS switches have been investigated using three dimensional (3D coupled multiphysics finite element (FE analysis. The coupled field analysis involved three consecutive multiphysics interactions. The first interaction is characterized as a two-way sequential electromagnetic (EM-thermal field coupling. The second interaction represented a one-way sequential thermal-structural field coupling. The third interaction portrayed a two-way sequential structural-electrostatic field coupling. An automated substructuring algorithm was utilized to reduce the computational cost of the complicated coupled multiphysics FE analysis. The results of the substructured FE model with coupled field analysis is shown to be in good agreement with the outcome of previously published experimental and numerical studies. The current numerical results indicate that the pull-in voltage and the buckling temperature of the RF switch are functions of the microfabrication residual stress state, the switch operational frequency and the surrounding packaging temperature. Furthermore, the current results point out that by introducing proper mechanical approaches such as corrugated switches and through-holes in the switch membrane, it is possible to achieve reliable pull-in voltages, at various operating temperatures. The performed analysis also shows that by controlling the mean and gradient residual stresses, generated during microfabrication, in conjunction with the proposed mechanical approaches, the power handling capability of RF MEMS switches can be increased, at a wide range of operational frequencies. These design features of RF MEMS switches are of particular importance in applications where a high RF power (frequencies above 10 GHz and large temperature variations are expected, such as in satellites and airplane condition monitoring.

Axisymmetric multiphase lattice Boltzmann method for generic equations of state

NARCIS (Netherlands)

Reijers, S.A.; Gelderblom, H.; Toschi, F.

2016-01-01

We present an axisymmetric lattice Boltzmann model based on the Kupershtokh et al. multiphase model that is capable of solving liquid–gas density ratios up to 103. Appropriate source terms are added to the lattice Boltzmann evolution equation to fully recover the axisymmetric multiphase conservation

Experimental Evaluation of Acoustic Engine Liner Models Developed with COMSOL Multiphysics

Science.gov (United States)

Schiller, Noah H.; Jones, Michael G.; Bertolucci, Brandon

2017-01-01

Accurate modeling tools are needed to design new engine liners capable of reducing aircraft noise. The purpose of this study is to determine if a commercially-available finite element package, COMSOL Multiphysics, can be used to accurately model a range of different acoustic engine liner designs, and in the process, collect and document a benchmark dataset that can be used in both current and future code evaluation activities. To achieve these goals, a variety of liner samples, ranging from conventional perforate-over-honeycomb to extended-reaction designs, were installed in one wall of the grazing flow impedance tube at the NASA Langley Research Center. The liners were exposed to high sound pressure levels and grazing flow, and the effect of the liner on the sound field in the flow duct was measured. These measurements were then compared with predictions. While this report only includes comparisons for a subset of the configurations, the full database of all measurements and predictions is available in electronic format upon request. The results demonstrate that both conventional perforate-over-honeycomb and extended-reaction liners can be accurately modeled using COMSOL. Therefore, this modeling tool can be used with confidence to supplement the current suite of acoustic propagation codes, and ultimately develop new acoustic engine liners designed to reduce aircraft noise.

Discrete modeling considerations in multiphase fluid dynamics

International Nuclear Information System (INIS)

Ransom, V.H.; Ramshaw, J.D.

1988-01-01

The modeling of multiphase flows play a fundamental role in light water reactor safety. The main ingredients in our discrete modeling Weltanschauung are the following considerations: (1) Any physical model must be cast into discrete form for a digital computer. (2) The usual approach of formulating models in differential form and then discretizing them is potentially hazardous. It may be preferable to formulate the model in discrete terms from the outset. (3) Computer time and storage constraints limit the resolution that can be employed in practical calculations. These limits effectively define the physical phenomena, length scales, and time scales which cannot be directly represented in the calculation and therefore must be modeled. This information should be injected into the model formulation process at an early stage. (4) Practical resolution limits are generally so coarse that traditional convergence and truncation-error analyses become irrelevant. (5) A discrete model constitutes a reduced description of a physical system, from which fine-scale details are eliminated. This elimination creates a statistical closure problem. Methods from statistical physics may therefore be useful in the formulation of discrete models. In the present paper we elaborate on these themes and illustrate them with simple examples. 48 refs

On the effect of operating conditions in liquid-feed direct methanol fuel cells: A multiphysics modeling approach

International Nuclear Information System (INIS)

García-Salaberri, Pablo A.; Vera, Marcos

2016-01-01

A multiphysics model for liquid-feed Direct Methanol Fuel Cells is presented. The model accounts for two-dimensional (2D) across-the-channel anisotropic mass and charge transport in the anode and cathode Gas Diffusion Layers (GDLs), including the effect of GDL assembly compression and electrical contact resistances at the Bipolar Plate (BPP) and membrane interfaces. A one-dimensional (1D) across-the-membrane model is used to describe local species diffusion through the microporous layers, methanol/water crossover, proton transport, and electrochemical reactions, thereby coupling both GDL sub-models. The 2D/1D model is extended to the third dimension and supplemented with 1D descriptions of the flow channels to yield a 3D/1D + 1D model that is successfully validated. A parametric study is then conducted on the 2D/1D model to examine the effect of operating conditions on cell performance. The results show that an optimum methanol concentration exists that maximizes power output due to the trade-off between anode polarization and cathode mixed overpotential. For fixed methanol concentration, cell performance is largely affected by the oxygen supply rate, cell temperature, and liquid/gas saturation levels. There is also an optimal GDL compression due to the trade-off between ohmic and concentration losses, which strongly depends on BPP material and, more weakly, on the actual operating conditions. - Highlights: • A multiphysics model for liquid-feed DMFCs is presented. • GDL anisotropic transport, assembly compression, and ohmic contact resistances are considered. • The model is successfully validated against previous experimental data. • Optimum methanol concentrations, GDL compressions, and operating temperatures are reported. • Oxygen-starved conditions with spontaneous hydrogen evolution in the anode are also considered.

Multiphase flow and transport in porous media

Science.gov (United States)

Parker, J. C.

1989-08-01

Multiphase flow and transport of compositionally complex fluids in geologic media is of importance in a number of applied problems which have major social and economic effects. In petroleum reservoir engineering, efficient recovery of energy reserves is the principal goal. Unfortunately, some of these hydrocarbons and other organic chemicals often find their way unwanted into the soils and groundwater supplies. Removal in the latter case is predicated on ensuring the public health and safety. In this paper, principles of modeling fluid flow in systems containing up to three fluid phases (namely, water, air, and organic liquid) are described. Solution of the governing equations for multiphase flow requires knowledge of functional relationships between fluid pressures, saturations, and permeabilities which may be formulated on the basis of conceptual models of fluid-porous media interactions. Mechanisms of transport in multicomponent multiphase systems in which species may partition between phases are also described, and the governing equations are presented for the case in which local phase equilibrium may be assumed. A number of hypothetical numerical problems are presented to illustrate the physical behavior of systems in which multiphase flow and transport arise.

A Multi-physics Approach to Understanding Low Porosity Soils and Reservoir Rocks

Science.gov (United States)

Prasad, M.; Mapeli, C.; Livo, K.; Hasanov, A.; Schindler, M.; Ou, L.

2017-12-01

We present recent results on our multiphysics approach to rock physics. Thus, we evaluate geophysical measurements by simultaneously measuring petrophysical properties or imaging strains. In this paper, we present simultaneously measured acoustic and electrical anisotropy data as functions of pressure. Similarly, we present strains and strain localization images simultaneously acquired with acoustic measurements as well as NMR T2 relaxations on pressurized fluids as well as rocks saturated with these pressurized fluids. Such multiphysics experiments allow us to constrain and assign appropriate causative mechanisms to development rock physics models. They also allow us to decouple various effects, for example, fluid versus pressure, on geophysical measurements. We show applications towards reservoir characterization as well as CO2 sequestration applications.

Modelling transport phenomena in a multi-physics context

Energy Technology Data Exchange (ETDEWEB)

Marra, Francesco [Dipartimento di Ingegneria Chimica e Alimentare - Università degli studi di Salerno Via Ponte Don Melillo - 84084 Fisciano SA (Italy)

2015-01-22

Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

Modelling transport phenomena in a multi-physics context

Science.gov (United States)

Marra, Francesco

2015-01-01

Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

Modelling transport phenomena in a multi-physics context

International Nuclear Information System (INIS)

Marra, Francesco

2015-01-01

Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating

COMSOL Multiphysics Model for HLW Canister Filling

Energy Technology Data Exchange (ETDEWEB)

Kesterson, M. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-04-11

The U.S. Department of Energy (DOE) is building a Tank Waste Treatment and Immobilization Plant (WTP) at the Hanford Site in Washington to remediate 55 million gallons of radioactive waste that is being temporarily stored in 177 underground tanks. Efforts are being made to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product quality requirements. Wastes containing high concentrations of Al₂O₃ and Na₂O can contribute to nepheline (generally NaAlSiO₄) crystallization, which can sharply reduce the chemical durability of high level waste (HLW) glass. Nepheline crystallization can occur during slow cooling of the glass within the stainless steel canister. The purpose of this work was to develop a model that can be used to predict temperatures of the glass in a WTP HLW canister during filling and cooling. The intent of the model is to support scoping work in the laboratory. It is not intended to provide precise predictions of temperature profiles, but rather to provide a simplified representation of glass cooling profiles within a full scale, WTP HLW canister under various glass pouring rates. These data will be used to support laboratory studies for an improved understanding of the mechanisms of nepheline crystallization. The model was created using COMSOL Multiphysics, a commercially available software. The model results were compared to available experimental data, TRR-PLT-080, and were found to yield sufficient results for the scoping nature of the study. The simulated temperatures were within 60 ºC for the centerline, 0.0762m (3 inch) from centerline, and 0.2286m (9 inch) from centerline thermocouples once the thermocouples were covered with glass. The temperature difference between the experimental and simulated values reduced to 40 ºC, 4 hours after the thermocouple was covered, and down to 20 ºC, 6 hours after the thermocouple was covered

High-Fidelity Space-Time Adaptive Multiphysics Simulations in Nuclear Engineering

Energy Technology Data Exchange (ETDEWEB)

Solin, Pavel [Univ. of Reno, NV (United States); Ragusa, Jean [Texas A & M Univ., College Station, TX (United States)

2014-03-09

We delivered a series of fundamentally new computational technologies that have the potential to significantly advance the state-of-the-art of computer simulations of transient multiphysics nuclear reactor processes. These methods were implemented in the form of a C++ library, and applied to a number of multiphysics coupled problems relevant to nuclear reactor simulations.

High-Fidelity Space-Time Adaptive Multiphysics Simulations in Nuclear Engineering

International Nuclear Information System (INIS)

Solin, Pavel; Ragusa, Jean

2014-01-01

We delivered a series of fundamentally new computational technologies that have the potential to significantly advance the state-of-the-art of computer simulations of transient multiphysics nuclear reactor processes. These methods were implemented in the form of a C++ library, and applied to a number of multiphysics coupled problems relevant to nuclear reactor simulations.

An advanced modeling study on the impacts and atmospheric implications of multiphase dimethyl sulfide chemistry

Science.gov (United States)

Hoffmann, Erik Hans; Tilgner, Andreas; Schrödner, Roland; Bräuer, Peter; Wolke, Ralf; Herrmann, Hartmut

2016-01-01

Oceans dominate emissions of dimethyl sulfide (DMS), the major natural sulfur source. DMS is important for the formation of non-sea salt sulfate (nss-SO42−) aerosols and secondary particulate matter over oceans and thus, significantly influence global climate. The mechanism of DMS oxidation has accordingly been investigated in several different model studies in the past. However, these studies had restricted oxidation mechanisms that mostly underrepresented important aqueous-phase chemical processes. These neglected but highly effective processes strongly impact direct product yields of DMS oxidation, thereby affecting the climatic influence of aerosols. To address these shortfalls, an extensive multiphase DMS chemistry mechanism, the Chemical Aqueous Phase Radical Mechanism DMS Module 1.0, was developed and used in detailed model investigations of multiphase DMS chemistry in the marine boundary layer. The performed model studies confirmed the importance of aqueous-phase chemistry for the fate of DMS and its oxidation products. Aqueous-phase processes significantly reduce the yield of sulfur dioxide and increase that of methyl sulfonic acid (MSA), which is needed to close the gap between modeled and measured MSA concentrations. Finally, the simulations imply that multiphase DMS oxidation produces equal amounts of MSA and sulfate, a result that has significant implications for nss-SO42− aerosol formation, cloud condensation nuclei concentration, and cloud albedo over oceans. Our findings show the deficiencies of parameterizations currently used in higher-scale models, which only treat gas-phase chemistry. Overall, this study shows that treatment of DMS chemistry in both gas and aqueous phases is essential to improve the accuracy of model predictions. PMID:27688763

A self-taught artificial agent for multi-physics computational model personalization.

Science.gov (United States)

Neumann, Dominik; Mansi, Tommaso; Itu, Lucian; Georgescu, Bogdan; Kayvanpour, Elham; Sedaghat-Hamedani, Farbod; Amr, Ali; Haas, Jan; Katus, Hugo; Meder, Benjamin; Steidl, Stefan; Hornegger, Joachim; Comaniciu, Dorin

2016-12-01

Personalization is the process of fitting a model to patient data, a critical step towards application of multi-physics computational models in clinical practice. Designing robust personalization algorithms is often a tedious, time-consuming, model- and data-specific process. We propose to use artificial intelligence concepts to learn this task, inspired by how human experts manually perform it. The problem is reformulated in terms of reinforcement learning. In an off-line phase, Vito, our self-taught artificial agent, learns a representative decision process model through exploration of the computational model: it learns how the model behaves under change of parameters. The agent then automatically learns an optimal strategy for on-line personalization. The algorithm is model-independent; applying it to a new model requires only adjusting few hyper-parameters of the agent and defining the observations to match. The full knowledge of the model itself is not required. Vito was tested in a synthetic scenario, showing that it could learn how to optimize cost functions generically. Then Vito was applied to the inverse problem of cardiac electrophysiology and the personalization of a whole-body circulation model. The obtained results suggested that Vito could achieve equivalent, if not better goodness of fit than standard methods, while being more robust (up to 11% higher success rates) and with faster (up to seven times) convergence rate. Our artificial intelligence approach could thus make personalization algorithms generalizable and self-adaptable to any patient and any model. Copyright © 2016. Published by Elsevier B.V.

Small strain multiphase-field model accounting for configurational forces and mechanical jump conditions

Science.gov (United States)

Schneider, Daniel; Schoof, Ephraim; Tschukin, Oleg; Reiter, Andreas; Herrmann, Christoph; Schwab, Felix; Selzer, Michael; Nestler, Britta

2018-03-01

Computational models based on the phase-field method have become an essential tool in material science and physics in order to investigate materials with complex microstructures. The models typically operate on a mesoscopic length scale resolving structural changes of the material and provide valuable information about the evolution of microstructures and mechanical property relations. For many interesting and important phenomena, such as martensitic phase transformation, mechanical driving forces play an important role in the evolution of microstructures. In order to investigate such physical processes, an accurate calculation of the stresses and the strain energy in the transition region is indispensable. We recall a multiphase-field elasticity model based on the force balance and the Hadamard jump condition at the interface. We show the quantitative characteristics of the model by comparing the stresses, strains and configurational forces with theoretical predictions in two-phase cases and with results from sharp interface calculations in a multiphase case. As an application, we choose the martensitic phase transformation process in multigrain systems and demonstrate the influence of the local homogenization scheme within the transition regions on the resulting microstructures.

Linear Power-Flow Models in Multiphase Distribution Networks: Preprint

Energy Technology Data Exchange (ETDEWEB)

Bernstein, Andrey; Dall' Anese, Emiliano

2017-05-26

This paper considers multiphase unbalanced distribution systems and develops approximate power-flow models where bus-voltages, line-currents, and powers at the point of common coupling are linearly related to the nodal net power injections. The linearization approach is grounded on a fixed-point interpretation of the AC power-flow equations, and it is applicable to distribution systems featuring (i) wye connections; (ii) ungrounded delta connections; (iii) a combination of wye-connected and delta-connected sources/loads; and, (iv) a combination of line-to-line and line-to-grounded-neutral devices at the secondary of distribution transformers. The proposed linear models can facilitate the development of computationally-affordable optimization and control applications -- from advanced distribution management systems settings to online and distributed optimization routines. Performance of the proposed models is evaluated on different test feeders.

Review of multi-physics temporal coupling methods for analysis of nuclear reactors

International Nuclear Information System (INIS)

Zerkak, Omar; Kozlowski, Tomasz; Gajev, Ivan

2015-01-01

Highlights: • Review of the numerical methods used for the multi-physics temporal coupling. • Review of high-order improvements to the Operator Splitting coupling method. • Analysis of truncation error due to the temporal coupling. • Recommendations on best-practice approaches for multi-physics temporal coupling. - Abstract: The advanced numerical simulation of a realistic physical system typically involves multi-physics problem. For example, analysis of a LWR core involves the intricate simulation of neutron production and transport, heat transfer throughout the structures of the system and the flowing, possibly two-phase, coolant. Such analysis involves the dynamic coupling of multiple simulation codes, each one devoted to the solving of one of the coupled physics. Multiple temporal coupling methods exist, yet the accuracy of such coupling is generally driven by the least accurate numerical scheme. The goal of this paper is to review in detail the approaches and numerical methods that can be used for the multi-physics temporal coupling, including a comprehensive discussion of the issues associated with the temporal coupling, and define approaches that can be used to perform multi-physics analysis. The paper is not limited to any particular multi-physics process or situation, but is intended to provide a generic description of multi-physics temporal coupling schemes for any development stage of the individual (single-physics) tools and methods. This includes a wide spectrum of situation, where the individual (single-physics) solvers are based on pre-existing computation codes embedded as individual components, or a new development where the temporal coupling can be developed and implemented as a part of code development. The discussed coupling methods are demonstrated in the framework of LWR core analysis

Multiphase flow experiments, mathematical modeling and numerical simulation of the water - gas - solute movement

Science.gov (United States)

Li, Y.; Ma, X.; Su, N.

2013-12-01

The movement of water and solute into and through the vadose zone is, in essence, an issue of immiscible displacement in pore-space network of a soil. Therefore, multiphase flow and transport in porous media, referring to three medium: air, water, and the solute, pose one of the largest unresolved challenges for porous medium fluid seepage. However, this phenomenon has always been largely neglected. It is expected that a reliable analysis model of the multi-phase flow in soil can truly reflect the process of natural movement about the infiltration, which is impossible to be observed directly. In such cases, geophysical applications of the nuclear magnetic resonance (NMR) provides the opportunity to measure the water movements into soils directly over a large scale from tiny pore to regional scale, accordingly enable it available both on the laboratory and on the field. In addition, the NMR provides useful information about the pore space properties. In this study, we proposed both laboratory and field experiments to measure the multi-phase flow parameters, together with optimize the model in computer programming based on the fractional partial differential equations (fPDE). In addition, we establish, for the first time, an infiltration model including solute flowing with water, which has huge influence on agriculture and soil environment pollution. Afterwards, with data collected from experiments, we simulate the model and analyze the spatial variability of parameters. Simulations are also conducted according to the model to evaluate the effects of airflow on water infiltration and other effects such as solute and absorption. It has significant meaning to oxygen irrigation aiming to higher crop yield, and shed more light into the dam slope stability. In summary, our framework is a first-time model added in solute to have a mathematic analysis with the fPDE and more instructive to agriculture activities.

Phase-field model simulation of ferroelectric/antiferroelectric materials microstructure evolution under multiphysics loading

Science.gov (United States)

Zhang, Jingyi

Ferroelectric (FE) and closely related antiferroelectric (AFE) materials have unique electromechanical properties that promote various applications in the area of capacitors, sensors, generators (FE) and high density energy storage (AFE). These smart materials with extensive applications have drawn wide interest in the industrial and scientific world because of their reliability and tunable property. However, reliability issues changes its paradigms and requires guidance from detailed mechanism theory as the materials applications are pushed for better performance. A host of modeling work were dedicated to study the macro-structural behavior and microstructural evolution in FE and AFE material under various conditions. This thesis is focused on direct observation of domain evolution under multiphysics loading for both FE and AFE material. Landau-Devonshire time-dependent phase field models were built for both materials, and were simulated in finite element software Comsol. In FE model, dagger-shape 90 degree switched domain was observed at preexisting crack tip under pure mechanical loading. Polycrystal structure was tested under same condition, and blocking effect of the growth of dagger-shape switched domain from grain orientation difference and/or grain boundary was directly observed. AFE ceramic model was developed using two sublattice theory, this model was used to investigate the mechanism of energy efficiency increase with self-confined loading in experimental tests. Consistent results was found in simulation and careful investigation of calculation results gave confirmation that origin of energy density increase is from three aspects: self-confinement induced inner compression field as the cause of increase of critical field, fringe leak as the source of elevated saturation polarization and uneven defects distribution as the reason for critical field shifting and phase transition speed. Another important affecting aspect in polycrystalline materials is the

A Novel Multi-Phase Stochastic Model for Lithium-Ion Batteries’ Degradation with Regeneration Phenomena

Directory of Open Access Journals (Sweden)

Jianxun Zhang

2017-10-01

Full Text Available A lithium-Ion battery is a typical degradation product, and its performance will deteriorate over time. In its degradation process, regeneration phenomena have been frequently encountered, which affect both the degradation state and rate. In this paper, we focus on how to build the degradation model and estimate the lifetime. Toward this end, we first propose a multi-phase stochastic degradation model with random jumps based on the Wiener process, where the multi-phase model and random jumps at the changing point are used to describe the variation of degradation rate and state caused by regeneration phenomena accordingly. Owing to the complex structure and random variables, the traditional Maximum Likelihood Estimation (MLE is not suitable for the proposed model. In this case, we treat these random variables as latent parameters, and then develop an approach for model identification based on expectation conditional maximum (ECM algorithm. Moreover, depending on the proposed model, how to estimate the lifetime with fixed changing point is presented via the time-space transformation technique, and the approximate analytical solution is derived. Finally, a numerical simulation and a practical case are provided for illustration.

Numerical simulation of complex multi-phase fluid of casting process and its applications

Directory of Open Access Journals (Sweden)

CHEN Li-liang

2006-05-01

Full Text Available The fluid of casting process is a typical kind of multi-phase flow. Actually, many casting phenomena have close relationship with the multi-phase flow, such as molten metal filling process, air entrapment, slag movement, venting process of die casting, gas escaping of lost foam casting and so on. Obviously, in order to analyze these phenomena accurately, numerical simulation of the multi-phase fluid is necessary. Unfortunately, so far, most of the commercial casting simulation systems do not have the ability of multi-phase flow modeling due to the difficulty in the multi-phase flow calculation. In the paper, Finite Different Method (FDM technique was adopt to solve the multi-phase fluid model. And a simple object of the muiti-phase fluid was analyzed to obtain the fluid rates of the liquid phase and the entrapped air phase.

Calculation model of non-linear dynamic deformation of composite multiphase rods

Directory of Open Access Journals (Sweden)

Mishchenko Andrey Viktorovich

2014-05-01

Full Text Available The method of formulating non-linear physical equations for multiphase rods is suggested in the article. Composite multiphase rods possess various structures, include shear, polar, radial and axial inhomogeneity. The Timoshenko’s hypothesis with the large rotation angles is used. The method is based on the approximation of longitudinal normal stress low by basic functions expansions regarding the linear viscosity low. The shear stresses are calculated with the equilibrium equation using the subsidiary function of the longitudinal shift force. The system of differential equations connecting the internal forces and temperature with abstract deformations are offered by the basic functions. The application of power functions with arbitrary index allows presenting the compact form equations. The functional coefficients in this system are the highest order rigidity characteristics. The whole multiphase cross-section rigidity characteristics are offered the sums of the rigidity characteristics of the same phases individually. The obtained system allows formulating the well-known particular cases. Among them: hard plasticity and linear elastic deformation, different module deformation and quadratic Gerstner’s low elastic deformation. The reform of differential equations system to the quasilinear is suggested. This system contains the secant variable rigidity characteristics depending on abstract deformations. This system includes the sum of the same uniform blocks of different order. The rods phases defined the various set of uniform blocks phase materials. The integration of dynamic, kinematic and physical equations taking into account initial and edge condition defines the full dynamical multiphase rods problem. The quasilinear physical equations allow getting the variable flexibility matrix of multiphase rod and rods system.

Interfacial mixing in high-energy-density matter with a multiphysics kinetic model

Science.gov (United States)

Haack, Jeffrey R.; Hauck, Cory D.; Murillo, Michael S.

2017-12-01

We have extended a recently developed multispecies, multitemperature Bhatnagar-Gross-Krook model [Haack et al., J. Stat. Phys. 168, 822 (2017), 10.1007/s10955-017-1824-9], to include multiphysics capabilities that enable modeling of a wider range of physical conditions. In terms of geometry, we have extended from the spatially homogeneous setting to one spatial dimension. In terms of the physics, we have included an atomic ionization model, accurate collision physics across coupling regimes, self-consistent electric fields, and degeneracy in the electronic screening. We apply the model to a warm dense matter scenario in which the ablator-fuel interface of an inertial confinement fusion target is heated, but for larger length and time scales and for much higher temperatures than can be simulated using molecular dynamics. Relative to molecular dynamics, the kinetic model greatly extends the temperature regime and the spatiotemporal scales over which we are able to model. In our numerical results we observe hydrogen from the ablator material jetting into the fuel during the early stages of the implosion and compare the relative size of various diffusion components (Fickean diffusion, electrodiffusion, and barodiffusion) that drive this process. We also examine kinetic effects, such as anisotropic distributions and velocity separation, in order to determine when this problem can be described with a hydrodynamic model.

Multiphysical modelling of fluid transport through osteo-articular media

Directory of Open Access Journals (Sweden)

Thibault Lemaire

2010-03-01

Full Text Available In this study, a multiphysical description of fluid transport through osteo-articular porous media is presented. Adapted from the model of Moyne and Murad, which is intended to describe clayey materials behaviour, this multiscale modelling allows for the derivation of the macroscopic response of the tissue from microscopical information. First the model is described. At the pore scale, electrohydrodynamics equations governing the electrolyte movement are coupled with local electrostatics (Gauss-Poisson equation, and ionic transport equations. Using a change of variables and an asymptotic expansion method, the macroscopic description is carried out. Results of this model are used to show the importance of couplings effects on the mechanotransduction of compact bone remodelling.Neste estudo uma descrição multifísica do transporte de fluidos em meios porosos osteo articulares é apresentada. Adaptado a partir do modelo de Moyne e Murad proposto para descrever o comportamento de materiais argilosos a modelagem multiescala permite a derivação da resposta macroscópica do tecido a partir da informação microscópica. Na primeira parte o modelo é apresentado. Na escala do poro as equações da eletro-hidrodinâmica governantes do movimento dos eletrolitos são acopladas com a eletrostática local (equação de Gauss-Poisson e as equações de transporte iônico. Usando uma mudança de variáveis e o método de expansão assintótica a derivação macroscópica é conduzida. Resultados do modelo proposto são usados para salientar a importância dos efeitos de acoplamento sobre a transdução mecânica da remodelagem de ossos compactados.

An introduction to LIME 1.0 and its use in coupling codes for multiphysics simulations.

Energy Technology Data Exchange (ETDEWEB)

Belcourt, Noel; Pawlowski, Roger Patrick; Schmidt, Rodney Cannon; Hooper, Russell Warren

2011-11-01

LIME is a small software package for creating multiphysics simulation codes. The name was formed as an acronym denoting 'Lightweight Integrating Multiphysics Environment for coupling codes.' LIME is intended to be especially useful when separate computer codes (which may be written in any standard computer language) already exist to solve different parts of a multiphysics problem. LIME provides the key high-level software (written in C++), a well defined approach (with example templates), and interface requirements to enable the assembly of multiple physics codes into a single coupled-multiphysics simulation code. In this report we introduce important software design characteristics of LIME, describe key components of a typical multiphysics application that might be created using LIME, and provide basic examples of its use - including the customized software that must be written by a user. We also describe the types of modifications that may be needed to individual physics codes in order for them to be incorporated into a LIME-based multiphysics application.

Development of Next Generation Multiphase Pipe Flow Prediction Tools

Energy Technology Data Exchange (ETDEWEB)

Cem Sarica; Holden Zhang

2006-05-31

The developments of oil and gas fields in deep waters (5000 ft and more) will become more common in the future. It is inevitable that production systems will operate under multiphase flow conditions (simultaneous flow of gas, oil and water possibly along with sand, hydrates, and waxes). Multiphase flow prediction tools are essential for every phase of hydrocarbon recovery from design to operation. Recovery from deep-waters poses special challenges and requires accurate multiphase flow predictive tools for several applications, including the design and diagnostics of the production systems, separation of phases in horizontal wells, and multiphase separation (topside, seabed or bottom-hole). It is crucial for any multiphase separation technique, either at topside, seabed or bottom-hole, to know inlet conditions such as flow rates, flow patterns, and volume fractions of gas, oil and water coming into the separation devices. Therefore, the development of a new generation of multiphase flow predictive tools is needed. The overall objective of the proposed study is to develop a unified model for gas-oil-water three-phase flow in wells, flow lines, and pipelines to predict flow characteristics such as flow patterns, phase distributions, and pressure gradient encountered during petroleum production at different flow conditions (pipe diameter and inclination, fluid properties and flow rates). In the current multiphase modeling approach, flow pattern and flow behavior (pressure gradient and phase fractions) prediction modeling are separated. Thus, different models based on different physics are employed, causing inaccuracies and discontinuities. Moreover, oil and water are treated as a pseudo single phase, ignoring the distinct characteristics of both oil and water, and often resulting in inaccurate design that leads to operational problems. In this study, a new model is being developed through a theoretical and experimental study employing a revolutionary approach. The

Optimization of coupled multiphysics methodology for safety analysis of pebble bed modular reactor

Science.gov (United States)

Mkhabela, Peter Tshepo

The research conducted within the framework of this PhD thesis is devoted to the high-fidelity multi-physics (based on neutronics/thermal-hydraulics coupling) analysis of Pebble Bed Modular Reactor (PBMR), which is a High Temperature Reactor (HTR). The Next Generation Nuclear Plant (NGNP) will be a HTR design. The core design and safety analysis methods are considerably less developed and mature for HTR analysis than those currently used for Light Water Reactors (LWRs). Compared to LWRs, the HTR transient analysis is more demanding since it requires proper treatment of both slower and much longer transients (of time scale in hours and days) and fast and short transients (of time scale in minutes and seconds). There is limited operation and experimental data available for HTRs for validation of coupled multi-physics methodologies. This PhD work developed and verified reliable high fidelity coupled multi-physics models subsequently implemented in robust, efficient, and accurate computational tools to analyse the neutronics and thermal-hydraulic behaviour for design optimization and safety evaluation of PBMR concept The study provided a contribution to a greater accuracy of neutronics calculations by including the feedback from thermal hydraulics driven temperature calculation and various multi-physics effects that can influence it. Consideration of the feedback due to the influence of leakage was taken into account by development and implementation of improved buckling feedback models. Modifications were made in the calculation procedure to ensure that the xenon depletion models were accurate for proper interpolation from cross section tables. To achieve this, the NEM/THERMIX coupled code system was developed to create the system that is efficient and stable over the duration of transient calculations that last over several tens of hours. Another achievement of the PhD thesis was development and demonstration of full-physics, three-dimensional safety analysis

Multiphysical Testing of Soils and Shales

CERN Document Server

Ferrari, Alessio

2013-01-01

Significant advancements in the experimental analysis of soils and shales have been achieved during the last few decades. Outstanding progress in the field has led to the theoretical development of geomechanical theories and important engineering applications. This book provides the reader with an overview of recent advances in a variety of advanced experimental techniques and results for the analysis of the behaviour of geomaterials under multiphysical testing conditions. Modern trends in experimental geomechanics for soils and shales are discussed, including testing materials in variably saturated conditions, non-isothermal experiments, micro-scale investigations and image analysis techniques. Six theme papers from leading researchers in experimental geomechanics are also included. This book is intended for postgraduate students, researchers and practitioners in fields where multiphysical testing of soils and shales plays a fundamental role, such as unsaturated soil and rock mechanics, petroleum engineering...

Multi-physics modeling of large ring motor for mining industry - Combining electromagnetism, fluid mechanics, mass and heat transfer in engineering design

DEFF Research Database (Denmark)

Andersen, Søren Bøgh; Santos, Ilmar F.; Fuerst, Axel

2015-01-01

This paper presents an improved completely interconnected procedure for estimating the losses, cooling flows, fluid characteristics and temperature distribution in a gearless mill drive using real life data. The presented model is part of a larger project building a multi-physics model combining...... iteratively according to the heat flux transferred to the fluid, is modeled as a lumped model with two nodes interconnected by 11 channels and one pump. The flow model is based on Bernoulli's energy equation and solved by Newton-Raphson method. All the results from the three physical areas have been verified...

A multiphysics and multiscale model for low frequency electromagnetic direct-chill casting

International Nuclear Information System (INIS)

Košnik, N; Guštin, A Z; Mavrič, B; Šarler, B

2016-01-01

Simulation and control of macrosegregation, deformation and grain size in low frequency electromagnetic (EM) direct-chill casting (LFEMC) is important for downstream processing. Respectively, a multiphysics and multiscale model is developed for solution of Lorentz force, temperature, velocity, concentration, deformation and grain structure of LFEMC processed aluminum alloys, with focus on axisymmetric billets. The mixture equations with lever rule, linearized phase diagram, and stationary thermoelastic solid phase are assumed, together with EM induction equation for the field imposed by the coil. Explicit diffuse approximate meshless solution procedure [1] is used for solving the EM field, and the explicit local radial basis function collocation method [2] is used for solving the coupled transport phenomena and thermomechanics fields. Pressure-velocity coupling is performed by the fractional step method [3]. The point automata method with modified KGT model is used to estimate the grain structure [4] in a post-processing mode. Thermal, mechanical, EM and grain structure outcomes of the model are demonstrated. A systematic study of the complicated influences of the process parameters can be investigated by the model, including intensity and frequency of the electromagnetic field. The meshless solution framework, with the implemented simplest physical models, will be further extended by including more sophisticated microsegregation and grain structure models, as well as a more realistic solid and solid-liquid phase rheology. (paper)

Multiphase Flow Dynamics 2 Mechanical Interactions

CERN Document Server

Kolev, Nikolay Ivanov

2012-01-01

Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. .In its fourth extended edition the successful monograph package “Multiphase Flow Daynmics” contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present second volume the methods for describing the mechanical interactions in multiphase dynamics are provided. This fourth edition includes various updates, extensions, improvements and corrections.   "The literature in the field of multiphase flows is numerous. Therefore, it i...

A Multi-Physics simulation of the Reactor Core using CUPID/MASTER

International Nuclear Information System (INIS)

Lee, Jae Ryong; Cho, Hyoung Kyu; Yoon, Han Young; Cho, Jin Young; Jeong, Jae Jun

2011-01-01

KAERI has been developing a component-scale thermal hydraulics code, CUPID. The aim of the code is for multi-dimensional, multi-physics and multi-scale thermal hydraulics analysis. In our previous papers, the CUPID code has proved to be able to reproduce multidimensional thermal hydraulic analysis by validated with various conceptual problems and experimental data. For the numerical closure, it adopts a three dimensional, transient, two-phase and three-field model, and includes physical models and correlations of the interfacial mass, momentum, and energy transfer. For the multi-scale analysis, the CUPID is on progress to merge into system-scale thermal hydraulic code, MARS. In the present paper, a multi-physics simulation was performed by coupling the CUPID with three dimensional neutron kinetics code, MASTER. The MASTER is merged into the CUPID as a dynamic link library (DLL). The APR1400 reactor core during control rod drop/ejection accident was simulated as an example by adopting a porous media approach to employ fuel assembly. The following sections present the numerical modeling for the reactor core, coupling of the kinetics code, and the simulation results

Multiphysics modeling of two-phase film boiling within porous corrosion deposits

Energy Technology Data Exchange (ETDEWEB)

Jin, Miaomiao, E-mail: mmjin@mit.edu; Short, Michael, E-mail: hereiam@mit.edu

2016-07-01

Porous corrosion deposits on nuclear fuel cladding, known as CRUD, can cause multiple operational problems in light water reactors (LWRs). CRUD can cause accelerated corrosion of the fuel cladding, increase radiation fields and hence greater exposure risk to plant workers once activated, and induce a downward axial power shift causing an imbalance in core power distribution. In order to facilitate a better understanding of CRUD's effects, such as localized high cladding surface temperatures related to accelerated corrosion rates, we describe an improved, fully-coupled, multiphysics model to simulate heat transfer, chemical reactions and transport, and two-phase fluid flow within these deposits. Our new model features a reformed assumption of 2D, two-phase film boiling within the CRUD, correcting earlier models' assumptions of single-phase coolant flow with wick boiling under high heat fluxes. This model helps to better explain observed experimental values of the effective CRUD thermal conductivity. Finally, we propose a more complete set of boiling regimes, or a more detailed mechanism, to explain recent CRUD deposition experiments by suggesting the new concept of double dryout specifically in thick porous media with boiling chimneys. - Highlights: • A two-phase model of CRUD's effects on fuel cladding is developed and improved. • This model eliminates the formerly erroneous assumption of wick boiling. • Higher fuel cladding temperatures are predicted when accounting for two-phase flow. • Double-peaks in thermal conductivity vs. heat flux in experiments are explained. • A “double dryout” mechanism in CRUD is proposed based on the model and experiments.

Multi-physics corrosion modeling for sustainability assessment of steel reinforced high performance fiber reinforced cementitious composites

DEFF Research Database (Denmark)

Lepech, M.; Michel, Alexander; Geiker, Mette

2016-01-01

and widespread depassivation, are the mechanism behind experimental results of HPFRCC steel corrosion studies found in the literature. Such results provide an indication of the fundamental mechanisms by which steel reinforced HPFRCC materials may be more durable than traditional reinforced concrete and other......Using a newly developed multi-physics transport, corrosion, and cracking model, which models these phenomena as a coupled physiochemical processes, the role of HPFRCC crack control and formation in regulating steel reinforcement corrosion is investigated. This model describes transport of water...... and chemical species, the electric potential distribution in the HPFRCC, the electrochemical propagation of steel corrosion, and the role of microcracks in the HPFRCC material. Numerical results show that the reduction in anode and cathode size on the reinforcing steel surface, due to multiple crack formation...

Multiphase flow dynamics 1 fundamentals

CERN Document Server

Kolev, Nikolay Ivanov

2004-01-01

Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. In its third extended edition this monograph contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present first volume the fundamentals of multiphase dynamics are provided. This third edition includes various updates, extensions and improvements in all book chapters.

Multiphysics modelling and simulation of dry laser cleaning of micro-slots with particle contaminants

International Nuclear Information System (INIS)

Yue Liyang; Wang Zengbo; Li Lin

2012-01-01

Light could interact differently with thin-film contaminants and particle contaminates because of their different surface morphologies. In the case of dry laser cleaning of small transparent particles, it is well known that particles could function like mini-lenses, causing a localized near-field hot spot effect on the cleaning process. This paper looks into a special, yet important, phenomenon of dry laser cleaning of particles trapped in micro-sized slots. The effects of slot size, particle size and particle aggregate states in the cleaning process have been theoretically investigated, based on a coupled electromagnetic-thermal-mechanical multiphysics modelling and simulation approach. The study is important for the development and optimization of laser cleaning processes for contamination removal from cracks and slots. (paper)

Experimentally validated multiphysics computational model of focusing and shock wave formation in an electromagnetic lithotripter.

Science.gov (United States)

Fovargue, Daniel E; Mitran, Sorin; Smith, Nathan B; Sankin, Georgy N; Simmons, Walter N; Zhong, Pei

2013-08-01

A multiphysics computational model of the focusing of an acoustic pulse and subsequent shock wave formation that occurs during extracorporeal shock wave lithotripsy is presented. In the electromagnetic lithotripter modeled in this work the focusing is achieved via a polystyrene acoustic lens. The transition of the acoustic pulse through the solid lens is modeled by the linear elasticity equations and the subsequent shock wave formation in water is modeled by the Euler equations with a Tait equation of state. Both sets of equations are solved simultaneously in subsets of a single computational domain within the BEARCLAW framework which uses a finite-volume Riemann solver approach. This model is first validated against experimental measurements with a standard (or original) lens design. The model is then used to successfully predict the effects of a lens modification in the form of an annular ring cut. A second model which includes a kidney stone simulant in the domain is also presented. Within the stone the linear elasticity equations incorporate a simple damage model.

IMPETUS - Interactive MultiPhysics Environment for Unified Simulations.

Science.gov (United States)

Ha, Vi Q; Lykotrafitis, George

2016-12-08

We introduce IMPETUS - Interactive MultiPhysics Environment for Unified Simulations, an object oriented, easy-to-use, high performance, C++ program for three-dimensional simulations of complex physical systems that can benefit a large variety of research areas, especially in cell mechanics. The program implements cross-communication between locally interacting particles and continuum models residing in the same physical space while a network facilitates long-range particle interactions. Message Passing Interface is used for inter-processor communication for all simulations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Three-dimensional multi-physics model of the European sodium fast reactor design applied to DBA analysis - 15293

International Nuclear Information System (INIS)

Lazaro, A.; Ordonez, J.; Martorell, S.; Przemyslaw, S.; Ammirabile, L.; Tsige-Tamirat, H.

2015-01-01

The sodium cooled fast reactor (SFR) is one of the reactor types selected by the Generation IV International Forum. SFR stand out due to its remarkable past operational experience in related projects and its potential to achieve the ambitious goals laid for the new generation of nuclear reactors. Regardless its operational experience, there is a need to apply computational tools able to simulate the system behaviour under conditions that may overtake the reactor safety limits from the early stages of the design process, including the three-dimensional phenomena that may arise in these transients. This paper presents the different steps followed towards the development of a multi-physics platform with capabilities to simulate complex phenomena using a coupled neutronic-thermal-hydraulic scheme. The development started with a one-dimensional thermal-hydraulic model of the European Sodium Fast Reactor (ESFR) design with point kinetic neutronic feedback benchmarked with its peers in the framework of the FP7-CP-ESFR project using the state-of-the-art thermal-hydraulic system code TRACE. The model was successively extended into a three-dimensional model coupled with the spatial kinetic neutronic code PARCS able to simulate three-dimensional multi-physic phenomena along with the comparison of the results for symmetric cases. The last part of the paper shows the application of the developed tool to the analysis of transients involving asymmetrical effects, such as the coast-down of a primary and secondary pump or the withdrawal of a peripheral control rod bank, demonstrating the unique capability of the code to simulate such transients and the capability of the design to withstand them under design basis

Accurate solution algorithms for incompressible multiphase flows

International Nuclear Information System (INIS)

Rider, W.J.; Kothe, D.B.; Mosso, S.J.; Cerutti, J.H.; Hochstein, J.I.

1994-01-01

A number of advances in modeling multiphase incompressible flow are described. These advances include high-order Godunov projection methods, piecewise linear interface reconstruction and tracking and the continuum surface force model. Examples are given

Optimization of an implicit constrained multi-physics system for motor wheels of electric vehicle

International Nuclear Information System (INIS)

Lei, Fei; Du, Bin; Liu, Xin; Xie, Xiaoping; Chai, Tian

2016-01-01

In this paper, implicit constrained multi-physics model of a motor wheel for an electric vehicle is built and then optimized. A novel optimization approach is proposed to solve the compliance problem between implicit constraints and stochastic global optimization. Firstly, multi-physics model of motor wheel is built from the theories of structural mechanics, electromagnetism and thermal physics. Then, implicit constraints are applied from the vehicle performances and magnetic characteristics. Implicit constrained optimization is carried out by a series of unconstrained optimization and verifications. In practice, sequentially updated subspaces are designed to completely substitute the original design space in local areas. In each subspace, a solution is obtained and is then verified by the implicit constraints. Optimal solutions which satisfy the implicit constraints are accepted as final candidates. The final global optimal solution is optimized from those candidates. Discussions are carried out to discover the differences between optimal solutions with unconstrained problem and different implicit constrained problems. Results show that the implicit constraints have significant influences on the optimal solution and the proposed approach is effective in finding the optimals. - Highlights: • An implicit constrained multi-physics model is built for sizing a motor wheel. • Vehicle dynamic performances are applied as implicit constraints for nonlinear system. • An efficient novel optimization is proposed to explore the constrained design space. • The motor wheel is optimized to achieve maximum efficiency on vehicle dynamics. • Influences of implicit constraints on vehicle performances are compared and analyzed.

International Symposium of Cavitation and Multiphase Flow (ISCM 2014)

International Nuclear Information System (INIS)

Wu, Yulin

2015-01-01

The International Symposium on Cavitation and Multiphase Flow (ISCM 2014) was held in Beijing, China during 18th-21st October, 2014, which was jointly organized by Tsinghua University, Beijing, China and Jiangsu University, Zhenjiang, China. The co-organizer was the State Key Laboratory of Hydroscience and Engineering, Beijing, China. Cavitation and multiphase flow is one of paramount topics of fluid mechanics with many engineering applications covering a broad range of topics, e.g. hydraulic machinery, biomedical engineering, chemical and process industry. In order to improve the performances of engineering facilities (e.g. hydraulic turbines) and to accelerate the development of techniques for medical treatment of serious diseases (e.g. tumors), it is essential to improve our understanding of cavitation and Multiphase Flow. For example, the present development towards the advanced hydrodynamic systems (e.g. space engine, propeller, hydraulic machinery system) often requires that the systems run under cavitating conditions and the risk of cavitation erosion needs to be controlled. The purpose of the ISCM 2014 was to discuss the state-of-the-art cavitation and multiphase flow research and their up-to-date applications, and to foster discussion and exchange of knowledge, and to provide an opportunity for the researchers, engineers and graduate students to report their latest outputs in these fields. Furthermore, the participants were also encouraged to present their work in progress with short lead time and discuss the encountered problems. ISCM 2014 covers all aspects of cavitation and Multiphase Flow, e.g. both fundamental and applied research with a focus on physical insights, numerical modelling and applications in engineering. Some specific topics are: Cavitating and Multiphase Flow in hydroturbines, pumps, propellers etc. Numerical simulation techniques Cavitation and multiphase flow erosion and anti-erosion techniques Measurement techniques for cavitation and

Multiphysics Modelling of Sodium Sulfur Battery

Science.gov (United States)

Mason, Jerry Hunter

Due to global climate change and the desire to decrease greenhouse gas emissions, large scale energy storage has become a critical issue. Renewable energy sources such as wind and solar will not be a viable energy source unless the storage problem is solved. One of the practical and cost effective solutions for this problem is sodium sulfur batteries. These batteries are comprised of liquid electrode materials suspended in porous media and operate at relatively high temperatures (>300°C). The sodium anode and the sulfur/sodium-polysulfide cathode are separated by a solid electrolyte made of beta-alumina or NASICON material. Due to the use of porous materials in the electrodes, capillary pressure and the combination of capillary action and gravity become important. Capillary pressure has a strong dependence on the wetting phase (liquid electrode material) saturation; therefore sharp concentration gradients can occur between the inert gas and the electrode liquid, especially within the cathode. These concentration gradients can have direct impacts on the electrodynamics of the battery as they may produce areas of high electrical potential variation, which can decrease efficiency and even cause failures. Then, thermal management also becomes vital since the electrochemistry and material properties are sensitive to temperature gradients. To investigate these phenomena in detail and to attempt to improve upon battery design a multi-dimensional, multi-phase code has been developed and validated in this study. Then a porous media flow model is implemented. Transport equations for charge, mass and heat are solved in a time marching fashion using finite volume method. Material properties are calculated and updated as a function of time. The porous media model is coupled with the continuity equation and a separate diffusion equation for the liquid sodium in the melt. The total mass transport model is coupled with charge transport via Faraday's law. Results show that

Thermal expansion model for multiphase electronic packaging materials

International Nuclear Information System (INIS)

Allred, B.E.; Warren, W.E.

1991-01-01

Control of thermal expansion is often necessary in the design and selection of electronic packages. In some instances, it is desirable to have a coefficient of thermal expansion intermediate between values readily attainable with single or two phase materials. The addition of a third phase in the form of fillers, whiskers, or fibers can be used to attain intermediate expansions. To help design the thermal expansion of multiphase materials for specific applications, a closed form model has been developed that accurately predicts the effective elastic properties of isotropic filled materials and transversely isotropic lamina. Properties of filled matrix materials are used as inputs to the lamina model to obtain the composite elastic properties as a function of the volume fraction of each phase. Hybrid composites with two or more fiber types are easily handled with this model. This paper reports that results for glass, quartz, and Kevlar fibers with beta-eucryptite filled polymer matrices show good agreement with experimental results for X, Y, and Z thermal expansion coefficients

An integrated multiphysics model for friction stir welding of 6061 Aluminum alloy

Directory of Open Access Journals (Sweden)

M Nourani

2016-09-01

Full Text Available This article presents a new, combined ‘integrated’- ‘multiphysics’ model of friction stir welding (FSW where a set of governing equations from non-Newtonian incompressible fluid dynamics, conductive and convective heat transfer, and plain stress solid mechanics have been coupled for calculating the process variables and material behaviour both during and after welding. More specifically, regarding the multiphysics feature, the model is capable of simultaneously predicting the local distribution, location and magnitude of maximum temperature, strain, and strain rate fields around the tool pin during the process; while for the integrated (post-analysis part, the above predictions have been used to study the microstructure and residual stress field of welded parts within the same developed code. A slip/stick condition between the tool and workpiece, friction and deformation heat source, convection and conduction heat transfer in the workpiece, a solid mechanics-based viscosity definition, and the Zener-Hollomon- based rigid-viscoplastic material properties with solidus cut-off temperature and empirical softening regime have been employed. In order to validate all the predicted variables collectively, the model has been compared to a series of published case studies on individual/limited set of variables, as well as in-house experiments on FSW of aluminum 6061.

Entropic lattice Boltzmann model for charged leaky dielectric multiphase fluids in electrified jets.

Science.gov (United States)

Lauricella, Marco; Melchionna, Simone; Montessori, Andrea; Pisignano, Dario; Pontrelli, Giuseppe; Succi, Sauro

2018-03-01

We present a lattice Boltzmann model for charged leaky dielectric multiphase fluids in the context of electrified jet simulations, which are of interest for a number of production technologies including electrospinning. The role of nonlinear rheology on the dynamics of electrified jets is considered by exploiting the Carreau model for pseudoplastic fluids. We report exploratory simulations of charged droplets at rest and under a constant electric field, and we provide results for charged jet formation under electrospinning conditions.

The Fluxgate Magnetometer Simulation in Comsol Multiphysics

OpenAIRE

Kolomeytsev Andrey; Baranov Pavel; Zatonov Ivan

2018-01-01

This article describes the fluxgate magnetometer simulation in Comsol Multiphysics software package. The simulation results coincide with the experiment described earlier. Decomposition of the output signal by the Fourier coefficients shows a frequency doubling.

Multiphase Flow Dynamics 1 Fundamentals

CERN Document Server

Kolev, Nikolay Ivanov

2012-01-01

Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. In its fourth extended edition the successful monograph package “Multiphase Flow Dynmics” contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present first volume the local volume and time averaging is used to derive a complete set of conservation equations for three fluids each of them having multi components as constituents. Large parts of the book are devoted on the design of successful numerical methods for solving the...

Advanced computational modelling for drying processes – A review

International Nuclear Information System (INIS)

Defraeye, Thijs

2014-01-01

Highlights: • Understanding the product dehydration process is a key aspect in drying technology. • Advanced modelling thereof plays an increasingly important role for developing next-generation drying technology. • Dehydration modelling should be more energy-oriented. • An integrated “nexus” modelling approach is needed to produce more energy-smart products. • Multi-objective process optimisation requires development of more complete multiphysics models. - Abstract: Drying is one of the most complex and energy-consuming chemical unit operations. R and D efforts in drying technology have skyrocketed in the past decades, as new drivers emerged in this industry next to procuring prime product quality and high throughput, namely reduction of energy consumption and carbon footprint as well as improving food safety and security. Solutions are sought in optimising existing technologies or developing new ones which increase energy and resource efficiency, use renewable energy, recuperate waste heat and reduce product loss, thus also the embodied energy therein. Novel tools are required to push such technological innovations and their subsequent implementation. Particularly computer-aided drying process engineering has a large potential to develop next-generation drying technology, including more energy-smart and environmentally-friendly products and dryers systems. This review paper deals with rapidly emerging advanced computational methods for modelling dehydration of porous materials, particularly for foods. Drying is approached as a combined multiphysics, multiscale and multiphase problem. These advanced methods include computational fluid dynamics, several multiphysics modelling methods (e.g. conjugate modelling), multiscale modelling and modelling of material properties and the associated propagation of material property variability. Apart from the current challenges for each of these, future perspectives should be directed towards material property

Multiphase Flow Dynamics 3 Thermal Interactions

CERN Document Server

Kolev, Nikolay Ivanov

2012-01-01

Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. .In its fourth extended edition the successful monograph package “Multiphase Flow Daynmics” contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present third volume methods for describing of the thermal interactions in multiphase dynamics are provided. In addition a large number of valuable experiments is collected and predicted using the methods introduced in this monograph. In this way the accuracy of the methods is reve...

Multiscale mechanics of TRIP-assisted multiphase steels: II. Micromechanical modelling

International Nuclear Information System (INIS)

Lani, F.; Furnemont, Q.; Van Rompaey, T.; Delannay, F.; Jacques, P.J.; Pardoen, T.

2007-01-01

The stress and strain partitioning between the different phases of transformation-induced plasticity (TRIP)-aided multiphase steels is evaluated using a mean field homogenization approach. The change of the austenite volume fraction under straining is predicted using a micromechanics-based criterion for the martensitic transformation adapted to the case of small, isolated, transforming austenite grains. The parameters of the model are identified from the mechanical response and transformation kinetics measured under uniaxial tension for two steels differing essentially by the austenite stability. The model is validated by comparing the predictions with tests performed under different loading conditions: pure shear, intermediate biaxial and equibiaxial. An analysis of the effect of the austenite stability on strength and ductility provides guidelines for optimizing properties according to the stress state

The Fluxgate Magnetometer Simulation in Comsol Multiphysics

Directory of Open Access Journals (Sweden)

Kolomeytsev Andrey

2018-01-01

Full Text Available This article describes the fluxgate magnetometer simulation in Comsol Multiphysics software package. The simulation results coincide with the experiment described earlier. Decomposition of the output signal by the Fourier coefficients shows a frequency doubling.

Advanced graphical user interface for multi-physics simulations using AMST

Science.gov (United States)

Hoffmann, Florian; Vogel, Frank

2017-07-01

Numerical modelling of particulate matter has gained much popularity in recent decades. Advanced Multi-physics Simulation Technology (AMST) is a state-of-the-art three dimensional numerical modelling technique combining the eX-tended Discrete Element Method (XDEM) with Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) [1]. One major limitation of this code is the lack of a graphical user interface (GUI) meaning that all pre-processing has to be made directly in a HDF5-file. This contribution presents the first graphical pre-processor developed for AMST.

Carbon-steel corrosion in multiphase slug flow and CO2

International Nuclear Information System (INIS)

Villarreal, J.; Laverde, D.; Fuentes, C.

2006-01-01

Hydrocarbon multiphase flow may exhibit various geometric configurations or flow patterns. One of these flow patterns is known as multiphase slug flow. If CO 2 is present in hydrocarbons, the steel pipelines can be corroded as this process is probably enhanced by slug flow turbulence. A hydrodynamic circuit was built to study the CO 2 corrosion rates under different slug flow conditions. The experimental results show how the corrosion rate of a carbon-steel electrode varies according to the flow turbulence. The higher slug frequency used in this study was 80 slugs/min. Experimental results for pressure drop and slug length are in agreement with the Dukler and Hubbard [A model for gas-liquid slug flow in horizontal and near horizontal tubes, Ind. Eng. Chem. Fundam. 14 (1975) 337-347] multiphase flow model. Furthermore, the experimental slug frequencies are well correlated by the Shell and Gregory [Correlation of the liquid volume fraction in the slug for horizontal gas-liquid slug flow. Int. J. Multiphase Flow 4 (1978) 33-39] equations in horizontal pipes

Challenges in Downhole Multiphase Measurements

Energy Technology Data Exchange (ETDEWEB)

Aspelund, A.; Midttveit, Oe.; Richards, A.

1996-12-31

Permanent downhole multi-phase monitoring (DMM) can have several advantages in field development, such as increased flexibility in the development of multi-lateral and horizontal wells, optimisation of artificial lift systems and monitoring of multi-layered wells. This paper gives an overview of existing permanent downhole measurement systems and a status of topside and subsea multi-phase flow meters (MFM). The main focus is on the challenges in downhole multi-phase measurements. Topics to be taken into consideration for realization of a downhole multi-phase meter are discussed, such as actual flow conditions occurring at the point of measurement, which quantities that need to be measured, sensor principles, data processing needs and signal transmission capability. 9 refs., 9 figs.

Modeling studies of multiphase fluid and heat flow processes in nuclear waste isolation

International Nuclear Information System (INIS)

Pruess, K.

1989-01-01

Multiphase fluid and heat flow plays an important role in many problems relating to the disposal of nuclear wastes in geologic media. Examples include boiling and condensation processes near heat-generating wastes, flow of water and formation gas in partially saturated formations, evolution of a free gas phase from waste package corrosion in initially water-saturated environments, and redistribution (dissolution, transport and precipitation) of rock minerals in non-isothermal flow fields. Such processes may strongly impact upon waste package and repository design considerations and performance. This paper summarizes important physical phenomena occurring in multiphase and nonisothermal flows, as well as techniques for their mathematical modeling and numerical simulation. Illustrative applications are given for a number of specific fluid and heat flow problems, including: thermohydrologic conditions near heat-generating waste packages in the unsaturated zone; repositorywide convection effects in the unsaturated zone; effects of quartz dissolution and precipitation for disposal in the saturated zone; and gas pressurization and flow effects from corrosion of low-level waste packages

Multiphysics Simulation of Welding-Arc and Nozzle-Arc System: Mathematical-Model, Solution-Methodology and Validation

Science.gov (United States)

Pawar, Sumedh; Sharma, Atul

2018-01-01

This work presents mathematical model and solution methodology for a multiphysics engineering problem on arc formation during welding and inside a nozzle. A general-purpose commercial CFD solver ANSYS FLUENT 13.0.0 is used in this work. Arc formation involves strongly coupled gas dynamics and electro-dynamics, simulated by solution of coupled Navier-Stoke equations, Maxwell's equations and radiation heat-transfer equation. Validation of the present numerical methodology is demonstrated with an excellent agreement with the published results. The developed mathematical model and the user defined functions (UDFs) are independent of the geometry and are applicable to any system that involves arc-formation, in 2D axisymmetric coordinates system. The high-pressure flow of SF6 gas in the nozzle-arc system resembles arc chamber of SF6 gas circuit breaker; thus, this methodology can be extended to simulate arcing phenomenon during current interruption.

Toward a General Theory for Multiphase Turbulence Part I: Development and Gauging of the Model Equations

Energy Technology Data Exchange (ETDEWEB)

B. A. Kashiwa; W. B. VanderHeyden

2000-12-01

A formalism for developing multiphase turbulence models is introduced by analogy to the phenomenological method used for single-phase turbulence. A sample model developed using the formalism is given in detail. The procedure begins with ensemble averaging of the exact conservation equations, with closure accomplished by using a combination of analytical and experimental results from the literature. The resulting model is applicable to a wide range of common multiphase flows including gas-solid, liquid-solid and gas-liquid (bubbly) flows. The model is positioned for ready extension to three-phase turbulence, or for use in two-phase turbulence in which one phase is accounted for in multiple size classes, representing polydispersivity. The formalism is expected to suggest directions toward a more fundamentally based theory, similar to the way that early work in single-phase turbulence has led to the spectral theory. The approach is unique in that a portion of the total energy decay rate is ascribed to each phase, as is dictated by the exact averaged equations, and results in a transport equation for energy decay rate associated with each phase. What follows is a straightforward definition of a turbulent viscosity for each phase, and accounts for the effect of exchange of fluctuational energy among phases on the turbulent shear viscosity. The model also accounts for the effect of slip momentum transfer among the phases on the production of turbulence kinetic energy and on the tensor character of the Reynolds stress. Collisional effects, when appropriate, are included by superposition. The model reduces to a standard form in limit of a single, pure material, and is expected to do a credible job of describing multiphase turbulent flows in a wide variety of regimes using a single set of coefficients.

Multiphase flow measurement in the slug regime using ultrasonic measurement techniques and slug closure model

OpenAIRE

Al-lababidi , Salem

2006-01-01

Multiphase flow in the oil and gas industry covers a wide range of flows. Thus, over the last decade, the investigation, development and use of multiphase flow metering system have been a major focus for the industry worldwide. However, these meters do not perform well in slug flow conditions. The present work involves experimental investigations of multiphase flow measurement under slug flow conditions. A two-phase gas/liquid facility was designed and constructed at Cranfie...

Using a multiphase flow code to model the coupled effects of repository consolidation and multiphase brine and gas flow at the Waste Isolation Pilot Plant

International Nuclear Information System (INIS)

Freeze, G.A.; Larson, K.W.; Davies, P.B.; Webb, S.W.

1995-01-01

Long-term repository assessment must consider the processes of (1) gas generation, (2) room closure and expansions due to salt creep, and (3) multiphase (brine and gas) fluid flow, as well as the complex coupling between these three processes. The mechanical creep closure code SANCHO was used to simulate the closure of a single, perfectly sealed disposal room filled with water and backfill. SANCHO uses constitutive models to describe salt creep, waste consolidation, and backfill consolidation, Five different gas-generation rate histories were simulated, differentiated by a rate multiplier, f, which ranged from 0.0 (no gas generation) to 1.0 (expected gas generation under brine-dominated conditions). The results of the SANCHO f-series simulations provide a relationship between gas generation, room closure, and room pressure for a perfectly sealed room. Several methods for coupling this relationship with multiphase fluid flow into and out of a room were examined. Two of the methods are described

Engineering Multiphysics Research

Directory of Open Access Journals (Sweden)

Tom Eppes

2011-05-01

Full Text Available This paper describes an engineering undergraduate course that covers the methods and techniques of multiphysics modeling. Students become active participants in analysis and discovery by being challenged to solve a sequence of problems related to high priority technology areas. Projects range from power systems and thermal control of habitats to autonomous flight systems and harsh environment electronics. Working in a cooperative learning environment, teams encounter a series of assignments that build on existing skills while gradually expanding their knowledge and expertise in disciplines outside of their own. This project-based approach employs a scaffolding structure with assignments organized in progressively challenging modules supported by mentoring. Each project begins with a problem definition which requires consideration of factors and influences beyond a single discipline. Solution development then moves to setting material properties, boundary constraints and including the necessary physics engines. For many students, this is the first in depth exposure to problems with specialized terminologies, driving equations and limiting conditions. Lastly, solving and post processing are addressed exploring steady state, time-variant, frequency response, optimization and sensitivity methods. The paper discusses the teaching and learning strategies, course structure, outcome assessment and project examples.

FOREWORD: International Symposium of Cavitation and Multiphase Flow (ISCM 2014)

Science.gov (United States)

Wu, Yulin

2015-01-01

The International Symposium on Cavitation and Multiphase Flow (ISCM 2014) was held in Beijing, China during 18th-21st October, 2014, which was jointly organized by Tsinghua University, Beijing, China and Jiangsu University, Zhenjiang, China. The co-organizer was the State Key Laboratory of Hydroscience and Engineering, Beijing, China. Cavitation and multiphase flow is one of paramount topics of fluid mechanics with many engineering applications covering a broad range of topics, e.g. hydraulic machinery, biomedical engineering, chemical and process industry. In order to improve the performances of engineering facilities (e.g. hydraulic turbines) and to accelerate the development of techniques for medical treatment of serious diseases (e.g. tumors), it is essential to improve our understanding of cavitation and Multiphase Flow. For example, the present development towards the advanced hydrodynamic systems (e.g. space engine, propeller, hydraulic machinery system) often requires that the systems run under cavitating conditions and the risk of cavitation erosion needs to be controlled. The purpose of the ISCM 2014 was to discuss the state-of-the-art cavitation and multiphase flow research and their up-to-date applications, and to foster discussion and exchange of knowledge, and to provide an opportunity for the researchers, engineers and graduate students to report their latest outputs in these fields. Furthermore, the participants were also encouraged to present their work in progress with short lead time and discuss the encountered problems. ISCM 2014 covers all aspects of cavitation and Multiphase Flow, e.g. both fundamental and applied research with a focus on physical insights, numerical modelling and applications in engineering. Some specific topics are: Cavitating and Multiphase Flow in hydroturbines, pumps, propellers etc. Numerical simulation techniques Cavitation and multiphase flow erosion and anti-erosion techniques Measurement techniques for cavitation and

On the predictive capabilities of multiphase Darcy flow models

KAUST Repository

Icardi, Matteo; Prudhomme, Serge

2016-01-01

Darcy s law is a widely used model and the limit of its validity is fairly well known. When the flow is sufficiently slow and the porosity relatively homogeneous and low, Darcy s law is the homogenized equation arising from the Stokes and Navier- Stokes equations and depends on a single effective parameter (the absolute permeability). However when the model is extended to multiphase flows, the assumptions are much more restrictive and less realistic. Therefore it is often used in conjunction with empirical models (such as relative permeability and capillary pressure curves), derived usually from phenomenological speculations and experimental data fitting. In this work, we present the results of a Bayesian calibration of a two-phase flow model, using high-fidelity DNS numerical simulation (at the pore-scale) in a realistic porous medium. These reference results have been obtained from a Navier-Stokes solver coupled with an explicit interphase-tracking scheme. The Bayesian inversion is performed on a simplified 1D model in Matlab by using adaptive spectral method. Several data sets are generated and considered to assess the validity of this 1D model.

On the predictive capabilities of multiphase Darcy flow models

KAUST Repository

Icardi, Matteo

2016-01-09

Darcy s law is a widely used model and the limit of its validity is fairly well known. When the flow is sufficiently slow and the porosity relatively homogeneous and low, Darcy s law is the homogenized equation arising from the Stokes and Navier- Stokes equations and depends on a single effective parameter (the absolute permeability). However when the model is extended to multiphase flows, the assumptions are much more restrictive and less realistic. Therefore it is often used in conjunction with empirical models (such as relative permeability and capillary pressure curves), derived usually from phenomenological speculations and experimental data fitting. In this work, we present the results of a Bayesian calibration of a two-phase flow model, using high-fidelity DNS numerical simulation (at the pore-scale) in a realistic porous medium. These reference results have been obtained from a Navier-Stokes solver coupled with an explicit interphase-tracking scheme. The Bayesian inversion is performed on a simplified 1D model in Matlab by using adaptive spectral method. Several data sets are generated and considered to assess the validity of this 1D model.

Multiphysics Integrated Coupling Environment (MICE) User Manual

Energy Technology Data Exchange (ETDEWEB)

Varija Agarwal; Donna Post Guillen

2013-08-01

The complex, multi-part nature of waste glass melters used in nuclear waste vitrification poses significant modeling challenges. The focus of this project has been to couple a 1D MATLAB model of the cold cap region within a melter with a 3D STAR-CCM+ model of the melter itself. The Multiphysics Integrated Coupling Environment (MICE) has been developed to create a cohesive simulation of a waste glass melter that accurately represents the cold cap. The one-dimensional mathematical model of the cold cap uses material properties, axial heat, and mass fluxes to obtain a temperature profile for the cold cap, the region where feed-to-glass conversion occurs. The results from Matlab are used to update simulation data in the three-dimensional STAR-CCM+ model so that the cold cap is appropriately incorporated into the 3D simulation. The two processes are linked through ModelCenter integration software using time steps that are specified for each process. Data is to be exchanged circularly between the two models, as the inputs and outputs of each model depend on the other.

Modeling Subgrid Scale Droplet Deposition in Multiphase-CFD

Science.gov (United States)

Agostinelli, Giulia; Baglietto, Emilio

2017-11-01

The development of first-principle-based constitutive equations for the Eulerian-Eulerian CFD modeling of annular flow is a major priority to extend the applicability of multiphase CFD (M-CFD) across all two-phase flow regimes. Two key mechanisms need to be incorporated in the M-CFD framework, the entrainment of droplets from the liquid film, and their deposition. Here we focus first on the aspect of deposition leveraging a separate effects approach. Current two-field methods in M-CFD do not include appropriate local closures to describe the deposition of droplets in annular flow conditions. As many integral correlations for deposition have been proposed for lumped parameters methods applications, few attempts exist in literature to extend their applicability to CFD simulations. The integral nature of the approach limits its applicability to fully developed flow conditions, without geometrical or flow variations, therefore negating the scope of CFD application. A new approach is proposed here that leverages local quantities to predict the subgrid-scale deposition rate. The methodology is first tested into a three-field approach CFD model.

Using COMSOL Multiphysics Software to Analyze the Thin Film Resistance Model of a Conductor on PET

Science.gov (United States)

Carradero-Santiago, Carolyn; Merced-Sanabria, Milzaida; Vedrine-Pauléus, Josee

2015-03-01

In this research work, we will develop a virtual model to analyze the electrical conductivity of a thin film with three layers, one of graphene or conducting metal film, polyethylene terephthalate (PET) and Poly(3,4-ethylenedioxythiophene) Polystyrene sulfonate (PEDOT:PSS). COMSOL Multiphysics will be the software use to develop the virtual model to analyze the thin-film layers. COMSOL software allows simulation and modelling of physical phenomena represented by differential equations such as that of heat transfer, fluid movement, electromagnetism and structural mechanics. In the work, we will define the geometry of the model; in this case we want three layers-PET, the conducting layer and PEDOT:PSS. We will then add the materials and assign PET as the lower layer, the above conductor as the middle layer and the PEDOT:PSS as the upper layer. We will analyze the model with varying thickness of the top conducting layer. This simulation will allow us to analyze the electrical conductivity, and visualize the model with varying voltage potential, or bias across the plates.

Multiphysics Based Thermal Modeling of a Pouch Lithium-Ion Battery Cell for the Development of Pack Level Thermal Management System

DEFF Research Database (Denmark)

Khan, Mohammad Rezwan; Kær, Søren Knudsen

2016-01-01

The research is focused on the development of a three-dimensional cell level multiphysics battery thermal model. The primary aim is to represent the cooling mechanism inside the unit cell battery pack. It is accomplished through the coupling of heat transfer and computational fluid dynamics (CFD......) physics. A lumped value of heat generation (HG) inside the battery cell is used. It stems from isothermal calorimeter experiment. HG depends on current rate and the corresponding operating temperature. It is demonstrated that the developed model provides a deeper understanding of the thermal spatio......-temporal behavior of Li-ion battery in different operating conditions....

Modeling and observational constraints on the sulfur cycle in the marine troposphere: a focus on reactive halogens and multiphase chemistry

Science.gov (United States)

Chen, Q.; Breider, T.; Schmidt, J.; Sherwen, T.; Evans, M. J.; Xie, Z.; Quinn, P.; Bates, T. S.; Alexander, B.

2017-12-01

The radiative forcing from marine boundary layer clouds is still highly uncertain, which partly stems from our poor understanding of cloud condensation nuclei (CCN) formation. The oxidation of dimethyl sulfide (DMS) and subsequent chemical evolution of its products (e.g. DMSO) are key processes in CCN formation, but are generally very simplified in large-scale models. Recent research has pointed out the importance of reactive halogens (e.g. BrO and Cl) and multiphase chemistry in the tropospheric sulfur cycle. In this study, we implement a series of sulfur oxidation mechanisms into the GEOS-Chem global chemical transport model, involving both gas-phase and multiphase oxidation of DMS, DMSO, MSIA and MSA, to improve our understanding of the sulfur cycle in the marine troposphere. DMS observations from six locations around the globe and MSA/nssSO42- ratio observations from two ship cruises covering a wide range of latitudes and longitudes are used to assess the model. Preliminary results reveal the important role of BrO for DMS oxidation at high latitudes (up to 50% over Southern Ocean). Oxidation of DMS by Cl radicals is small in the model (within 10% in the marine troposphere), probably due to an underrepresentation of Cl sources. Multiphase chemistry (e.g. oxidation by OH and O3 in cloud droplets) is not important for DMS oxidation but is critical for DMSO oxidation and MSA production and removal. In our model, about half of the DMSO is oxidized in clouds, leading to the formation of MSIA, which is further oxidized to form MSA. Overall, with the addition of reactive halogens and multiphase chemistry, the model is able to better reproduce observations of seasonal variations of DMS and MSA/nssSO42- ratios.

ALE3D: An Arbitrary Lagrangian-Eulerian Multi-Physics Code

Energy Technology Data Exchange (ETDEWEB)

Noble, Charles R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Anderson, Andrew T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Barton, Nathan R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bramwell, Jamie A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Capps, Arlie [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chang, Michael H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chou, Jin J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dawson, David M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Diana, Emily R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dunn, Timothy A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Faux, Douglas R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fisher, Aaron C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Greene, Patrick T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Heinz, Ines [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kanarska, Yuliya [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Khairallah, Saad A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Liu, Benjamin T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Margraf, Jon D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nichols, Albert L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nourgaliev, Robert N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Puso, Michael A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Reus, James F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Robinson, Peter B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shestakov, Alek I. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Solberg, Jerome M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Taller, Daniel [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tsuji, Paul H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); White, Christopher A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); White, Jeremy L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-05-23

ALE3D is a multi-physics numerical simulation software tool utilizing arbitrary-Lagrangian- Eulerian (ALE) techniques. The code is written to address both two-dimensional (2D plane and axisymmetric) and three-dimensional (3D) physics and engineering problems using a hybrid finite element and finite volume formulation to model fluid and elastic-plastic response of materials on an unstructured grid. As shown in Figure 1, ALE3D is a single code that integrates many physical phenomena.

Modelación y simulación de disipadores de calor para procesadores de computadora en COMSOL Multiphysics Modeling and simulation of heat sinks for computer processors in COMSOL Multiphysics

Directory of Open Access Journals (Sweden)

Sulin Garro Acón

2012-11-01

Full Text Available En este estudio se analizó la transferencia de calor en tres disipadores de calor utilizados para enfriar los procesadores de computadoras de escritorio. El objetivo de estos disipadores es evitar el sobrecalentamiento de la unidad de procesamiento y la consecuente reducción de la vida útil del computador. Los disipadores de calor se modelaron usando COMSOL Multiphysics con las dimensiones reales de los dispositivos y la generación de calor se modeló con una fuente puntual. Luego se modificaron los diseños de los disipadores para lograr una temperatura más baja en la zona más caliente del procesador. El resultado fue una reducción en la temperatura en el rango de 5-78 grados Kelvin, al rediseñarse el disipador de calor con variaciones feasibles como la reducción del grosor de las placas de intercambio de calor y el aumento de su número. Esto demuestra la posibilidad de desarrollar diseños optimizados para disipadores de calor que no requieran más materiales sino una mejor ingeniería. El trabajo se inició como parte del curso CM-4101 Modelización y Simulación.In this study, the heat transfer of three desktop- computer heat sinks was analyzed. The objective of using these heat sinks is to avoid overheating of the computer’s processing unit and in turn reduce the corresponding loss in the unit’s service time. The heat sinks were modeled using COMSOL Multiphysics with the actual dimensions of the devices, and heat generation was modeled with a point source. In the next step, the heat sink designs were modified to achieve a lower temperature in the higher temperature location on the heat sink. The results were temperature reductions in the range of 5-78 degrees Kelvin, by making feasible variations in design such as reducing the thickness of the heat exchanger fins and increasing their number. This paper demonstrates that there is room to develop improved designs that do not require more materials but rather a better engineering

Modeling studies for multiphase fluid and heat flow processes in nuclear waste isolation

International Nuclear Information System (INIS)

Pruess, K.

1988-07-01

Multiphase fluid and heat flow plays an important role in many problems relating to the disposal of nuclear wastes in geologic media. Examples include boiling and condensation processes near heat-generating wastes, flow of water and formation gas in partially saturated formations, evolution of a free gas phase from waste package corrosion in initially water-saturated environments, and redistribution (dissolution, transport, and precipitation) of rock minerals in non-isothermal flow fields. Such processes may strongly impact upon waste package and repository design considerations and performance. This paper summarizes important physical phenomena occurring in multiphase and nonisothermal flows, as well as techniques for their mathematical modeling and numerical simulation. Illustrative applications are given for a number of specific fluid and heat flow problems, including: thermohydrologic conditions near heat-generating waste packages in the unsaturated zone; repository-wide convection effects in the unsaturated zone; effects of quartz dissolution and precipitation for disposal in the saturated zone; and gas pressurization and flow corrosion of low-level waste packages. 34 refs; 7 figs; 2 tabs

A Multiphase Non-Linear Mixed Effects Model: An Application to Spirometry after Lung Transplantation

Science.gov (United States)

Rajeswaran, Jeevanantham; Blackstone, Eugene H.

2014-01-01

In medical sciences, we often encounter longitudinal temporal relationships that are non-linear in nature. The influence of risk factors may also change across longitudinal follow-up. A system of multiphase non-linear mixed effects model is presented to model temporal patterns of longitudinal continuous measurements, with temporal decomposition to identify the phases and risk factors within each phase. Application of this model is illustrated using spirometry data after lung transplantation using readily available statistical software. This application illustrates the usefulness of our flexible model when dealing with complex non-linear patterns and time varying coefficients. PMID:24919830

Specification of the Advanced Burner Test Reactor Multi-Physics Coupling Demonstration Problem

Energy Technology Data Exchange (ETDEWEB)

Shemon, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States); Grudzinski, J. J. [Argonne National Lab. (ANL), Argonne, IL (United States); Lee, C. H. [Argonne National Lab. (ANL), Argonne, IL (United States); Thomas, J. W. [Argonne National Lab. (ANL), Argonne, IL (United States); Yu, Y. Q. [Argonne National Lab. (ANL), Argonne, IL (United States)

2015-12-21

This document specifies the multi-physics nuclear reactor demonstration problem using the SHARP software package developed by NEAMS. The SHARP toolset simulates the key coupled physics phenomena inside a nuclear reactor. The PROTEUS neutronics code models the neutron transport within the system, the Nek5000 computational fluid dynamics code models the fluid flow and heat transfer, and the DIABLO structural mechanics code models structural and mechanical deformation. The three codes are coupled to the MOAB mesh framework which allows feedback from neutronics, fluid mechanics, and mechanical deformation in a compatible format.

A novel multiphysic model for simulation of swelling equilibrium of ionized thermal-stimulus responsive hydrogels

Science.gov (United States)

Li, Hua; Wang, Xiaogui; Yan, Guoping; Lam, K. Y.; Cheng, Sixue; Zou, Tao; Zhuo, Renxi

2005-03-01

In this paper, a novel multiphysic mathematical model is developed for simulation of swelling equilibrium of ionized temperature sensitive hydrogels with the volume phase transition, and it is termed the multi-effect-coupling thermal-stimulus (MECtherm) model. This model consists of the steady-state Nernst-Planck equation, Poisson equation and swelling equilibrium governing equation based on the Flory's mean field theory, in which two types of polymer-solvent interaction parameters, as the functions of temperature and polymer-network volume fraction, are specified with or without consideration of the hydrogen bond interaction. In order to examine the MECtherm model consisting of nonlinear partial differential equations, a meshless Hermite-Cloud method is used for numerical solution of one-dimensional swelling equilibrium of thermal-stimulus responsive hydrogels immersed in a bathing solution. The computed results are in very good agreements with experimental data for the variation of volume swelling ratio with temperature. The influences of the salt concentration and initial fixed-charge density are discussed in detail on the variations of volume swelling ratio of hydrogels, mobile ion concentrations and electric potential of both interior hydrogels and exterior bathing solution.

Multiphase flow dynamics 1 fundamentals

CERN Document Server

Kolev, Nikolay Ivanov

2015-01-01

In its fifth extended edition the successful monograph package “Multiphase Flow Dynamics” contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present first volume the local volume and time averaging is used to derive a complete set of conservation equations for three fluids each of them having multi components as constituents. Large parts of the book are devoted on the design of successful numerical methods for solving the obtained system of partial differential equations. Finally the analysis is repeated for boundary fitted curvilinear coordinate systems designing methods applicable for interconnected multi-blocks. This fifth edition includes various updates, extensions, improvements and corrections, as well as  a completely new chapter containing the basic physics describing the multi-phase flow in tu...

Shock tube Multiphase Experiments

Science.gov (United States)

Middlebrooks, John; Allen, Roy; Paudel, Manoj; Young, Calvin; Musick, Ben; McFarland, Jacob

2017-11-01

Shock driven multiphase instabilities (SDMI) are unique physical phenomena that have far-reaching practical applications in engineering and science. The instability is present in high energy explosions, scramjet combustors, and supernovae events. The SDMI arises when a multiphase interface is impulsively accelerated by the passage of a shockwave. It is similar in development to the Richtmyer-Meshkov (RM) instability however, particle-to-gas coupling is the driving mechanism of the SDMI. As particle effects such as lag and phase change become more prominent, the SDMI's development begins to significantly deviate from the RM instability. We have developed an experiment for studying the SDMI in our shock tube facility. In our experiments, a multiphase interface is created using a laminar jet and flowed into the shock tube where it is accelerated by the passage of a planar shockwave. The interface development is captured using CCD cameras synchronized with planar laser illumination. This talk will give an overview of new experiments conducted to examine the development of a shocked cylindrical multiphase interface. The effects of Atwood number, particle size, and a second acceleration (reshock) of the interface will be discussed.

Modeling of multiphase flow with solidification and chemical reaction in materials processing

Science.gov (United States)

Wei, Jiuan

Understanding of multiphase flow and related heat transfer and chemical reactions are the keys to increase the productivity and efficiency in industrial processes. The objective of this thesis is to utilize the computational approaches to investigate the multiphase flow and its application in the materials processes, especially in the following two areas: directional solidification, and pyrolysis and synthesis. In this thesis, numerical simulations will be performed for crystal growth of several III-V and II-VI compounds. The effects of Prandtl and Grashof numbers on the axial temperature profile, the solidification interface shape, and melt flow are investigated. For the material with high Prandtl and Grashof numbers, temperature field and growth interface will be significantly influenced by melt flow, resulting in the complicated temperature distribution and curved interface shape, so it will encounter tremendous difficulty using a traditional Bridgman growth system. A new design is proposed to reduce the melt convection. The geometric configuration of top cold and bottom hot in the melt will dramatically reduce the melt convection. The new design has been employed to simulate the melt flow and heat transfer in crystal growth with large Prandtl and Grashof numbers and the design parameters have been adjusted. Over 90% of commercial solar cells are made from silicon and directional solidification system is the one of the most important method to produce multi-crystalline silicon ingots due to its tolerance to feedstock impurities and lower manufacturing cost. A numerical model is developed to simulate the silicon ingot directional solidification process. Temperature distribution and solidification interface location are presented. Heat transfer and solidification analysis are performed to determine the energy efficiency of the silicon production furnace. Possible improvements are identified. The silicon growth process is controlled by adjusting heating power and

Modelling the Multiphase Flow in Dense Medium Cyclones

Directory of Open Access Journals (Sweden)

Kaiwei Chu

2010-12-01

Full Text Available Dense medium cyclone (DMC is widely used in mineral industry to separate solids by density. It is simple in design but the flow pattern within it is complex due to the size and density distributions of the feed and process medium solids, and the turbulent vortex formed. Recently, the so-called combined computational fluid dynamics (CFD and discrete element method (DEM (CFD-DEM was extended from two-phase flow to model the flow in DMCs at the University of New South Wales (UNSW. In the CFD-DEM model, the flow of coal particles is modelled by DEM and that of medium flow by CFD, allowing consideration of medium-coal mutual interaction and particle-particle collisions. In the DEM model, Newton's laws of motion are applied to individual particles, and in the CFD model the local-averaged Navier-Stokes equations combined with the volume of fluid (VOF and mixture multiphase flow models are solved. The application to the DMC studies requires intensive computational effort. Therefore, various simplified versions have been proposed, corresponding to the approaches such as Lagrangian particle tracking (LPT method where dilute phase flow is assumed so that the interaction between particles can be ignored, one-way coupling where the effect of particle flow on fluid flow is ignored, and the use of the concept of parcel particles whose properties are empirically determined. In this paper, the previous works on the modelling of DMCs at UNSW are summarized and the features and applicability of the models used are discussed.

Forcing scheme in pseudopotential lattice Boltzmann model for multiphase flows.

Science.gov (United States)

Li, Q; Luo, K H; Li, X J

2012-07-01

The pseudopotential lattice Boltzmann (LB) model is a widely used multiphase model in the LB community. In this model, an interaction force, which is usually implemented via a forcing scheme, is employed to mimic the molecular interactions that cause phase segregation. The forcing scheme is therefore expected to play an important role in the pseudoepotential LB model. In this paper, we aim to address some key issues about forcing schemes in the pseudopotential LB model. First, theoretical and numerical analyses will be made for Shan-Chen's forcing scheme [Shan and Chen, Phys. Rev. E 47, 1815 (1993)] and the exact-difference-method forcing scheme [Kupershtokh et al., Comput. Math. Appl. 58, 965 (2009)]. The nature of these two schemes and their recovered macroscopic equations will be shown. Second, through a theoretical analysis, we will reveal the physics behind the phenomenon that different forcing schemes exhibit different performances in the pseudopotential LB model. Moreover, based on the analysis, we will present an improved forcing scheme and numerically demonstrate that the improved scheme can be treated as an alternative approach to achieving thermodynamic consistency in the pseudopotential LB model.

Multiphasic Reaction Modeling for Polypropylene Production in a Pilot-Scale Catalytic Reactor

Directory of Open Access Journals (Sweden)

Mohammad Jakir Hossain Khan

2016-06-01

Full Text Available In this study, a novel multiphasic model for the calculation of the polypropylene production in a complicated hydrodynamic and the physiochemical environments has been formulated, confirmed and validated. This is a first research attempt that describes the development of the dual-phasic phenomena, the impact of the optimal process conditions on the production rate of polypropylene and the fluidized bed dynamic details which could be concurrently obtained after solving the model coupled with the CFD (computational fluid dynamics model, the basic mathematical model and the moment equations. Furthermore, we have established the quantitative relationship between the operational condition and the dynamic gas–solid behavior in actual reaction environments. Our results state that the proposed model could be applied for generalizing the production rate of the polymer from a chemical procedure to pilot-scale chemical reaction engineering. However, it was assumed that the solids present in the bubble phase and the reactant gas present in the emulsion phase improved the multiphasic model, thus taking into account that the polymerization took place mutually in the emulsion besides the bubble phase. It was observed that with respect to the experimental extent of the superficial gas velocity and the Ziegler-Natta feed rate, the ratio of the polymer produced as compared to the overall rate of production was approximately in the range of 9%–11%. This is a significant amount and it should not be ignored. We also carried out the simulation studies for comparing the data of the CFD-dependent dual-phasic model, the emulsion phase model, the dynamic bubble model and the experimental results. It was noted that the improved dual-phasic model and the CFD model were able to predict more constricted and safer windows at similar conditions as compared to the experimental results. Our work is unique, as the integrated developed model is able to offer clearer ideas

A Global Sensitivity Analysis Methodology for Multi-physics Applications

Energy Technology Data Exchange (ETDEWEB)

Tong, C H; Graziani, F R

2007-02-02

Experiments are conducted to draw inferences about an entire ensemble based on a selected number of observations. This applies to both physical experiments as well as computer experiments, the latter of which are performed by running the simulation models at different input configurations and analyzing the output responses. Computer experiments are instrumental in enabling model analyses such as uncertainty quantification and sensitivity analysis. This report focuses on a global sensitivity analysis methodology that relies on a divide-and-conquer strategy and uses intelligent computer experiments. The objective is to assess qualitatively and/or quantitatively how the variabilities of simulation output responses can be accounted for by input variabilities. We address global sensitivity analysis in three aspects: methodology, sampling/analysis strategies, and an implementation framework. The methodology consists of three major steps: (1) construct credible input ranges; (2) perform a parameter screening study; and (3) perform a quantitative sensitivity analysis on a reduced set of parameters. Once identified, research effort should be directed to the most sensitive parameters to reduce their uncertainty bounds. This process is repeated with tightened uncertainty bounds for the sensitive parameters until the output uncertainties become acceptable. To accommodate the needs of multi-physics application, this methodology should be recursively applied to individual physics modules. The methodology is also distinguished by an efficient technique for computing parameter interactions. Details for each step will be given using simple examples. Numerical results on large scale multi-physics applications will be available in another report. Computational techniques targeted for this methodology have been implemented in a software package called PSUADE.

Applied multiphase flow in pipes and flow assurance oil and gas production

CERN Document Server

Al-Safran, Eissa M

2017-01-01

Applied Multiphase Flow in Pipes and Flow Assurance - Oil and Gas Production delivers the most recent advancements in multiphase flow technology while remaining easy to read and appropriate for undergraduate and graduate petroleum engineering students. Responding to the need for a more up-to-the-minute resource, this highly anticipated new book represents applications on the fundamentals with new material on heat transfer in production systems, flow assurance, transient multiphase flow in pipes and the TUFFP unified model. The complex computation procedure of mechanistic models is simplified through solution flowcharts and several example problems. Containing over 50 solved example problems and 140 homework problems, this new book will equip engineers with the skills necessary to use the latest steady-state simulators available.

An Efficient Upscaling Process Based on a Unified Fine-scale Multi-Physics Model for Flow Simulation in Naturally Fracture Carbonate Karst Reservoirs

KAUST Repository

Bi, Linfeng

2009-01-01

The main challenges in modeling fluid flow through naturally-fractured carbonate karst reservoirs are how to address various flow physics in complex geological architectures due to the presence of vugs and caves which are connected via fracture networks at multiple scales. In this paper, we present a unified multi-physics model that adapts to the complex flow regime through naturally-fractured carbonate karst reservoirs. This approach generalizes Stokes-Brinkman model (Popov et al. 2007). The fracture networks provide the essential connection between the caves in carbonate karst reservoirs. It is thus very important to resolve the flow in fracture network and the interaction between fractures and caves to better understand the complex flow behavior. The idea is to use Stokes-Brinkman model to represent flow through rock matrix, void caves as well as intermediate flows in very high permeability regions and to use an idea similar to discrete fracture network model to represent flow in fracture network. Consequently, various numerical solution strategies can be efficiently applied to greatly improve the computational efficiency in flow simulations. We have applied this unified multi-physics model as a fine-scale flow solver in scale-up computations. Both local and global scale-up are considered. It is found that global scale-up has much more accurate than local scale-up. Global scale-up requires the solution of global flow problems on fine grid, which generally is computationally expensive. The proposed model has the ability to deal with large number of fractures and caves, which facilitate the application of Stokes-Brinkman model in global scale-up computation. The proposed model flexibly adapts to the different flow physics in naturally-fractured carbonate karst reservoirs in a simple and effective way. It certainly extends modeling and predicting capability in efficient development of this important type of reservoir.

Propagation of neutron-reaction uncertainties through multi-physics models of novel LWR's

Directory of Open Access Journals (Sweden)

Hernandez-Solis Augusto

2017-01-01

Full Text Available The novel design of the renewable boiling water reactor (RBWR allows a breeding ratio greater than unity and thus, it aims at providing for a self-sustained fuel cycle. The neutron reactions that compose the different microscopic cross-sections and angular distributions are uncertain, so when they are employed in the determination of the spatial distribution of the neutron flux in a nuclear reactor, a methodology should be employed to account for these associated uncertainties. In this work, the Total Monte Carlo (TMC method is used to propagate the different neutron-reactions (as well as angular distributions covariances that are part of the TENDL-2014 nuclear data (ND library. The main objective is to propagate them through coupled neutronic and thermal-hydraulic models in order to assess the uncertainty of important safety parameters related to multi-physics, such as peak cladding temperature along the axial direction of an RBWR fuel assembly. The objective of this study is to quantify the impact that ND covariances of important nuclides such as U-235, U-238, Pu-239 and the thermal scattering of hydrogen in H2O have in the deterministic safety analysis of novel nuclear reactors designs.

Multi-Physics Analysis of the Fermilab Booster RF Cavity

International Nuclear Information System (INIS)

Awida, M.; Reid, J.; Yakovlev, V.; Lebedev, V.; Khabiboulline, T.; Champion, M.

2012-01-01

After about 40 years of operation the RF accelerating cavities in Fermilab Booster need an upgrade to improve their reliability and to increase the repetition rate in order to support a future experimental program. An increase in the repetition rate from 7 to 15 Hz entails increasing the power dissipation in the RF cavities, their ferrite loaded tuners, and HOM dampers. The increased duty factor requires careful modelling for the RF heating effects in the cavity. A multi-physic analysis investigating both the RF and thermal properties of Booster cavity under various operating conditions is presented in this paper.

Particle force model effects in a shock-driven multiphase instability

Science.gov (United States)

Black, W. J.; Denissen, N.; McFarland, J. A.

2018-05-01

This work presents simulations on a shock-driven multiphase instability (SDMI) at an initial particle volume fraction of 1% with the addition of a suite of particle force models applicable in dense flows. These models include pressure-gradient, added-mass, and interparticle force terms in an effort to capture the effects neighboring particles have in non-dilute flow regimes. Two studies are presented here: the first seeks to investigate the individual contributions of the force models, while the second study focuses on examining the effect of these force models on the hydrodynamic evolution of a SDMI with various particle relaxation times (particle sizes). In the force study, it was found that the pressure gradient and interparticle forces have little effect on the instability under the conditions examined, while the added-mass force decreases the vorticity deposition and alters the morphology of the instability. The relaxation-time study likewise showed a decrease in metrics associated with the evolution of the SDMI for all sizes when the particle force models were included. The inclusion of these models showed significant morphological differences in both the particle and carrier species fields, which increased as particle relaxation times increased.

Two-Step Multi-Physics Analysis of an Annular Linear Induction Pump for Fission Power Systems

Science.gov (United States)

Geng, Steven M.; Reid, Terry V.

2016-01-01

One of the key technologies associated with fission power systems (FPS) is the annular linear induction pump (ALIP). ALIPs are used to circulate liquid-metal fluid for transporting thermal energy from the nuclear reactor to the power conversion device. ALIPs designed and built to date for FPS project applications have not performed up to expectations. A unique, two-step approach was taken toward the multi-physics examination of an ALIP using ANSYS Maxwell 3D and Fluent. This multi-physics approach was developed so that engineers could investigate design variations that might improve pump performance. Of interest was to determine if simple geometric modifications could be made to the ALIP components with the goal of increasing the Lorentz forces acting on the liquid-metal fluid, which in turn would increase pumping capacity. The multi-physics model first calculates the Lorentz forces acting on the liquid metal fluid in the ALIP annulus. These forces are then used in a computational fluid dynamics simulation as (a) internal boundary conditions and (b) source functions in the momentum equations within the Navier-Stokes equations. The end result of the two-step analysis is a predicted pump pressure rise that can be compared with experimental data.

Multiphase-field model of small strain elasto-plasticity according to the mechanical jump conditions

Science.gov (United States)

Herrmann, Christoph; Schoof, Ephraim; Schneider, Daniel; Schwab, Felix; Reiter, Andreas; Selzer, Michael; Nestler, Britta

2018-04-01

We introduce a small strain elasto-plastic multiphase-field model according to the mechanical jump conditions. A rate-independent J_2 -plasticity model with linear isotropic hardening and without kinematic hardening is applied exemplary. Generally, any physically nonlinear mechanical model is compatible with the subsequently presented procedure. In contrast to models with interpolated material parameters, the proposed model is able to apply different nonlinear mechanical constitutive equations for each phase separately. The Hadamard compatibility condition and the static force balance are employed as homogenization approaches to calculate the phase-inherent stresses and strains. Several verification cases are discussed. The applicability of the proposed model is demonstrated by simulations of the martensitic transformation and quantitative parameters.

A templated approach for multi-physics modeling of hybrid energy systems in Modelica

Energy Technology Data Exchange (ETDEWEB)

Greenwood, Michael Scott [ORNL; Cetiner, Sacit M. [ORNL; Harrison, Thomas J. [ORNL; Fugate, David [Oak Ridge National Laboratory (ORNL)

2018-01-01

A prototypical hybrid energy system (HES) couples a primary thermal power generator (i.e., nuclear power plant) with one or more additional subsystems beyond the traditional balance of plant electricity generation system. The definition and architecture of an HES can be adapted based on the needs and opportunities of a given local market. For example, locations in need of potable water may be best served by coupling a desalination plant to the HES. A location near an oil refinery may have a need for emission-free hydrogen production. The flexible, multidomain capabilities of Modelica are being used to investigate the dynamics (e.g., thermal hydraulics and electrical generation/consumption) of such a hybrid system. This paper examines the simulation infrastructure created to enable the coupling of multiphysics subsystem models for HES studies. A demonstration of a tightly coupled nuclear hybrid energy system implemented using the Modelica based infrastructure is presented for two representative cases. An appendix is also included providing a step-by-step procedure for using the template-based infrastructure.

Modeling non-isothermal multiphase multi-species reactive chemical transport in geologic media

Energy Technology Data Exchange (ETDEWEB)

Tianfu Xu; Gerard, F.; Pruess, K.; Brimhall, G.

1997-07-01

The assessment of mineral deposits, the analysis of hydrothermal convection systems, the performance of radioactive, urban and industrial waste disposal, the study of groundwater pollution, and the understanding of natural groundwater quality patterns all require modeling tools that can consider both the transport of dissolved species as well as their interactions with solid (or other) phases in geologic media and engineered barriers. Here, a general multi-species reactive transport formulation has been developed, which is applicable to homogeneous and/or heterogeneous reactions that can proceed either subject to local equilibrium conditions or kinetic rates under non-isothermal multiphase flow conditions. Two numerical solution methods, the direct substitution approach (DSA) and sequential iteration approach (SIA) for solving the coupled complex subsurface thermo-physical-chemical processes, are described. An efficient sequential iteration approach, which solves transport of solutes and chemical reactions sequentially and iteratively, is proposed for the current reactive chemical transport computer code development. The coupled flow (water, vapor, air and heat) and solute transport equations are also solved sequentially. The existing multiphase flow code TOUGH2 and geochemical code EQ3/6 are used to implement this SIA. The flow chart of the coupled code TOUGH2-EQ3/6, required modifications of the existing codes and additional subroutines needed are presented.

A Cell-Centered Multiphase ALE Scheme With Structural Coupling

Energy Technology Data Exchange (ETDEWEB)

Dunn, Timothy Alan [Univ. of California, Davis, CA (United States)

2012-04-16

A novel computational scheme has been developed for simulating compressible multiphase flows interacting with solid structures. The multiphase fluid is computed using a Godunov-type finite-volume method. This has been extended to allow computations on moving meshes using a direct arbitrary-Eulerian- Lagrangian (ALE) scheme. The method has been implemented within a Lagrangian hydrocode, which allows modeling the interaction with Lagrangian structural regions. Although the above scheme is general enough for use on many applications, the ultimate goal of the research is the simulation of heterogeneous energetic material, such as explosives or propellants. The method is powerful enough for application to all stages of the problem, including the initial burning of the material, the propagation of blast waves, and interaction with surrounding structures. The method has been tested on a number of canonical multiphase tests as well as fluid-structure interaction problems.

Efficient topology optimisation of multiscale and multiphysics problems

DEFF Research Database (Denmark)

Alexandersen, Joe

The aim of this Thesis is to present efficient methods for optimising high-resolution problems of a multiscale and multiphysics nature. The Thesis consists of two parts: one treating topology optimisation of microstructural details and the other treating topology optimisation of conjugate heat...

Dry calibration of electromagnetic flowmeters based on numerical models combining multiple physical phenomena (multiphysics)

Science.gov (United States)

Fu, X.; Hu, L.; Lee, K. M.; Zou, J.; Ruan, X. D.; Yang, H. Y.

2010-10-01

This paper presents a method for dry calibration of an electromagnetic flowmeter (EMF). This method, which determines the voltage induced in the EMF as conductive liquid flows through a magnetic field, numerically solves a coupled set of multiphysical equations with measured boundary conditions for the magnetic, electric, and flow fields in the measuring pipe of the flowmeter. Specifically, this paper details the formulation of dry calibration and an efficient algorithm (that adaptively minimizes the number of measurements and requires only the normal component of the magnetic flux density as boundary conditions on the pipe surface to reconstruct the magnetic field involved) for computing the sensitivity of EMF. Along with an in-depth discussion on factors that could significantly affect the final precision of a dry calibrated EMF, the effects of flow disturbance on measuring errors have been experimentally studied by installing a baffle at the inflow port of the EMF. Results of the dry calibration on an actual EMF were compared against flow-rig calibration; excellent agreements (within 0.3%) between dry calibration and flow-rig tests verify the multiphysical computation of the fields and the robustness of the method. As requiring no actual flow, the dry calibration is particularly useful for calibrating large-diameter EMFs where conventional flow-rig methods are often costly and difficult to implement.

Dynamic dielectrophoresis model of multi-phase ionic fluids.

Directory of Open Access Journals (Sweden)

Ying Yan

Full Text Available Ionic-based dielectrophoretic microchips have attracted significant attention due to their wide-ranging applications in electro kinetic and biological experiments. In this work, a numerical method is used to simulate the dynamic behaviors of ionic droplets in a microchannel under the effect of dielectrophoresis. When a discrete liquid dielectric is encompassed within a continuous fluid dielectric placed in an electric field, an electric force is produced due to the dielectrophoresis effect. If either or both of the fluids are ionic liquids, the magnitude and even the direction of the force will be changed because the net ionic charge induced by an electric field can affect the polarization degree of the dielectrics. However, using a dielectrophoresis model, assuming ideal dielectrics, results in significant errors. To avoid the inaccuracy caused by the model, this work incorporates the electrode kinetic equation and defines a relationship between the polarization charge and the net ionic charge. According to the simulation conditions presented herein, the electric force obtained in this work has an error exceeding 70% of the actual value if the false effect of net ionic charge is not accounted for, which would result in significant issues in the design and optimization of experimental parameters. Therefore, there is a clear motivation for developing a model adapted to ionic liquids to provide precise control for the dielectrophoresis of multi-phase ionic liquids.

Dynamic dielectrophoresis model of multi-phase ionic fluids.

Science.gov (United States)

Yan, Ying; Luo, Jing; Guo, Dan; Wen, Shizhu

2015-01-01

Ionic-based dielectrophoretic microchips have attracted significant attention due to their wide-ranging applications in electro kinetic and biological experiments. In this work, a numerical method is used to simulate the dynamic behaviors of ionic droplets in a microchannel under the effect of dielectrophoresis. When a discrete liquid dielectric is encompassed within a continuous fluid dielectric placed in an electric field, an electric force is produced due to the dielectrophoresis effect. If either or both of the fluids are ionic liquids, the magnitude and even the direction of the force will be changed because the net ionic charge induced by an electric field can affect the polarization degree of the dielectrics. However, using a dielectrophoresis model, assuming ideal dielectrics, results in significant errors. To avoid the inaccuracy caused by the model, this work incorporates the electrode kinetic equation and defines a relationship between the polarization charge and the net ionic charge. According to the simulation conditions presented herein, the electric force obtained in this work has an error exceeding 70% of the actual value if the false effect of net ionic charge is not accounted for, which would result in significant issues in the design and optimization of experimental parameters. Therefore, there is a clear motivation for developing a model adapted to ionic liquids to provide precise control for the dielectrophoresis of multi-phase ionic liquids.

A semi-implicit, second-order-accurate numerical model for multiphase underexpanded volcanic jets

Directory of Open Access Journals (Sweden)

S. Carcano

2013-11-01

Full Text Available An improved version of the PDAC (Pyroclastic Dispersal Analysis Code, Esposti Ongaro et al., 2007 numerical model for the simulation of multiphase volcanic flows is presented and validated for the simulation of multiphase volcanic jets in supersonic regimes. The present version of PDAC includes second-order time- and space discretizations and fully multidimensional advection discretizations in order to reduce numerical diffusion and enhance the accuracy of the original model. The model is tested on the problem of jet decompression in both two and three dimensions. For homogeneous jets, numerical results are consistent with experimental results at the laboratory scale (Lewis and Carlson, 1964. For nonequilibrium gas–particle jets, we consider monodisperse and bidisperse mixtures, and we quantify nonequilibrium effects in terms of the ratio between the particle relaxation time and a characteristic jet timescale. For coarse particles and low particle load, numerical simulations well reproduce laboratory experiments and numerical simulations carried out with an Eulerian–Lagrangian model (Sommerfeld, 1993. At the volcanic scale, we consider steady-state conditions associated with the development of Vulcanian and sub-Plinian eruptions. For the finest particles produced in these regimes, we demonstrate that the solid phase is in mechanical and thermal equilibrium with the gas phase and that the jet decompression structure is well described by a pseudogas model (Ogden et al., 2008. Coarse particles, on the other hand, display significant nonequilibrium effects, which associated with their larger relaxation time. Deviations from the equilibrium regime, with maximum velocity and temperature differences on the order of 150 m s−1 and 80 K across shock waves, occur especially during the rapid acceleration phases, and are able to modify substantially the jet dynamics with respect to the homogeneous case.

PRELIMINARY COUPLING OF THE MONTE CARLO CODE OPENMC AND THE MULTIPHYSICS OBJECT-ORIENTED SIMULATION ENVIRONMENT (MOOSE) FOR ANALYZING DOPPLER FEEDBACK IN MONTE CARLO SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Matthew Ellis; Derek Gaston; Benoit Forget; Kord Smith

2011-07-01

In recent years the use of Monte Carlo methods for modeling reactors has become feasible due to the increasing availability of massively parallel computer systems. One of the primary challenges yet to be fully resolved, however, is the efficient and accurate inclusion of multiphysics feedback in Monte Carlo simulations. The research in this paper presents a preliminary coupling of the open source Monte Carlo code OpenMC with the open source Multiphysics Object-Oriented Simulation Environment (MOOSE). The coupling of OpenMC and MOOSE will be used to investigate efficient and accurate numerical methods needed to include multiphysics feedback in Monte Carlo codes. An investigation into the sensitivity of Doppler feedback to fuel temperature approximations using a two dimensional 17x17 PWR fuel assembly is presented in this paper. The results show a functioning multiphysics coupling between OpenMC and MOOSE. The coupling utilizes Functional Expansion Tallies to accurately and efficiently transfer pin power distributions tallied in OpenMC to unstructured finite element meshes used in MOOSE. The two dimensional PWR fuel assembly case also demonstrates that for a simplified model the pin-by-pin doppler feedback can be adequately replicated by scaling a representative pin based on pin relative powers.

Problems of multiphase fluid filtration

CERN Document Server

Konovalov, AN

1994-01-01

This book deals with a spectrum of problems related to the mathematical modeling of multiphase filtration. Emphasis is placed on an inseparable triad: model - algorithm - computer code. An analysis of new and traditional filtration problems from the point of view of both their numerical implementation and the reproduction of one or another technological characteristics of the processes under consideration is given. The basic principles which underlie the construction of efficient numerical methods taking into account the filtration problems are discussed: non-evolutionary nature, degeneration,

Progress and challenges in the development and qualification of multi-level multi-physics coupled methodologies for reactor analysis

International Nuclear Information System (INIS)

Ivanov, K.; Avramova, M.

2007-01-01

Current trends in nuclear power generation and regulation as well as the design of next generation reactor concepts along with the continuing computer technology progress stimulate the development, qualification and application of multi-physics multi-scale coupled code systems. The efforts have been focused on extending the analysis capabilities by coupling models, which simulate different phenomena or system components, as well as on refining the scale and level of detail of the coupling. This paper reviews the progress made in this area and outlines the remaining challenges. The discussion is illustrated with examples based on neutronics/thermohydraulics coupling in the reactor core modeling. In both fields recent advances and developments are towards more physics-based high-fidelity simulations, which require implementation of improved and flexible coupling methodologies. First, the progresses in coupling of different physics codes along with the advances in multi-level techniques for coupled code simulations are discussed. Second, the issues related to the consistent qualification of coupled multi-physics and multi-scale code systems for design and safety evaluation are presented. The increased importance of uncertainty and sensitivity analysis are discussed along with approaches to propagate the uncertainty quantification between the codes. The incoming OECD LWR Uncertainty Analysis in Modeling (UAM) benchmark is the first international activity to address this issue and it is described in the paper. Finally, the remaining challenges with multi-physics coupling are outlined. (authors)

Progress and challenges in the development and qualification of multi-level multi-physics coupled methodologies for reactor analysis

Energy Technology Data Exchange (ETDEWEB)

Ivanov, K.; Avramova, M. [Pennsylvania State Univ., University Park, PA (United States)

2007-07-01

Current trends in nuclear power generation and regulation as well as the design of next generation reactor concepts along with the continuing computer technology progress stimulate the development, qualification and application of multi-physics multi-scale coupled code systems. The efforts have been focused on extending the analysis capabilities by coupling models, which simulate different phenomena or system components, as well as on refining the scale and level of detail of the coupling. This paper reviews the progress made in this area and outlines the remaining challenges. The discussion is illustrated with examples based on neutronics/thermohydraulics coupling in the reactor core modeling. In both fields recent advances and developments are towards more physics-based high-fidelity simulations, which require implementation of improved and flexible coupling methodologies. First, the progresses in coupling of different physics codes along with the advances in multi-level techniques for coupled code simulations are discussed. Second, the issues related to the consistent qualification of coupled multi-physics and multi-scale code systems for design and safety evaluation are presented. The increased importance of uncertainty and sensitivity analysis are discussed along with approaches to propagate the uncertainty quantification between the codes. The incoming OECD LWR Uncertainty Analysis in Modeling (UAM) benchmark is the first international activity to address this issue and it is described in the paper. Finally, the remaining challenges with multi-physics coupling are outlined. (authors)

Multiphase Flow Dynamics 4 Turbulence, Gas Adsorption and Release, Diesel Fuel Properties

CERN Document Server

Kolev, Nikolay Ivanov

2012-01-01

The present Volume 4 of the successful monograh package “Multiphase Flow Dynamics”is devoted to selected Chapters of the multiphase fluid dynamics that are important for practical applications but did not find place in the previous volumes. The state of the art of the turbulence modeling in multiphase flows is presented. As introduction, some basics of the single phase boundary layer theory including some important scales and flow oscillation characteristics in pipes and rod bundles are presented. Then the scales characterizing the dispersed flow systems are presented. The description of the turbulence is provided at different level of complexity: simple algebraic models for eddy viscosity, simple algebraic models based on the Boussinesq hypothesis, modification of the boundary layer share due to modification of the bulk turbulence, modification of the boundary layer share due to nucleate boiling. The role of the following forces on the mathematical description of turbulent flows is discussed: the lift fo...

Analysis of multiphase flows using dual-energy gamma densitometry and neural networks

International Nuclear Information System (INIS)

Bishop, C.M.; James, G.D.

1993-01-01

Dual-energy gamma densitometry offers a powerful technique for the non-intrusive analysis of multiphase flows. By employing multiple beam lines, information on the phase configuration can be obtained. Once the configuration is known, it then becomes possible in principle to determine the phase fractions. In practice, however, the extraction of the phase fractions from the densitometer data is complicated by the wide variety of phase configurations which can arise, and by the considerable difficulties of modelling multiphase flows. In this paper we show that neural network techniques provide a powerful approach to the analysis of data from dual-energy gamma densitometers, allowing both the phase configuration and the phase fractions to be determined with high accuracy, whilst avoiding the uncertainties associated with modelling. The technique is well suited to the determination of oil, water and gas fractions in multiphase oil pipelines. Results from linear and non-linear network models are compared, and a new technique for validating the network output is described. (orig.)

Multiphase flow dynamics 2 thermal and mechanical interactions

CERN Document Server

Kolev, Nikolay I

2007-01-01

The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. This book contains theory, methods and practical experience for describing complex transient multi-phase processes. It provides a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics.

Evaluation of the atmospheric significance of multiphase reactions in atmospheric secondary organic aerosol formation

Directory of Open Access Journals (Sweden)

Gelencsér

2005-01-01

Full Text Available In a simple conceptual cloud-aerosol model the mass of secondary organic aerosol (SOA that may be formed in multiphase reaction in an idealized scenario involving two cloud cycles separated with a cloud-free period is evaluated. The conditions are set to those typical of continental clouds, and each parameter used in the model calculations is selected as a mean of available observational data of individual species for which the multiphase SOA formation route has been established. In the idealized setting gas and aqueous-phase reactions are both considered, but only the latter is expected to yield products of sufficiently low volatility to be retained by aerosol particles after the cloud dissipates. The key variable of the model is the Henry-constant which primarily determines how important multiphase reactions are relative to gas-phase photooxidation processes. The precursor considered in the model is assumed to already have some affinity to water, i.e. it is a compound having oxygen-containing functional group(s. As a principal model output an aerosol yield parameter is calculated for the multiphase SOA formation route as a function of the Henry-constant, and has been found to be significant already above H~103 M atm-1. Among the potential precursors that may be eligible for this mechanism based on their Henry constants, there are a suite of oxygenated compounds such as primary oxidation products of biogenic and anthropogenic hydrocarbons, including, for example, pinonaldehyde. Finally, the analogy of multiphase SOA formation to in-cloud sulfate production is exploited.

Multi-physic simulations of irradiation experiments in a technological irradiation reactor

International Nuclear Information System (INIS)

Bonaccorsi, Th.

2007-09-01

A Material Testing Reactor (MTR) makes it possible to irradiate material samples under intense neutron and photonic fluxes. These experiments are carried out in experimental devices localised in the reactor core or in periphery (reflector). Available physics simulation tools only treat, most of the time, one physics field in a very precise way. Multi-physic simulations of irradiation experiments therefore require a sequential use of several calculation codes and data exchanges between these codes: this corresponds to problems coupling. In order to facilitate multi-physic simulations, this thesis sets up a data model based on data-processing objects, called Technological Entities. This data model is common to all of the physics fields. It permits defining the geometry of an irradiation device in a parametric way and to associate information about materials to it. Numerical simulations are encapsulated into interfaces providing the ability to call specific functionalities with the same command (to initialize data, to launch calculations, to post-treat, to get results,... ). Thus, once encapsulated, numerical simulations can be re-used for various studies. This data model is developed in a SALOME platform component. The first application case made it possible to perform neutronic simulations (OSIRIS reactor and RJH) coupled with fuel behavior simulations. In a next step, thermal hydraulics could also be taken into account. In addition to the improvement of the calculation accuracy due to the physical phenomena coupling, the time spent in the development phase of the simulation is largely reduced and the possibilities of uncertainty treatment are under consideration. (author)

Coupled multi-physics simulation frameworks for reactor simulation: A bottom-up approach

International Nuclear Information System (INIS)

Tautges, Timothy J.; Caceres, Alvaro; Jain, Rajeev; Kim, Hong-Jun; Kraftcheck, Jason A.; Smith, Brandon M.

2011-01-01

A 'bottom-up' approach to multi-physics frameworks is described, where first common interfaces to simulation data are developed, then existing physics modules are adapted to communicate through those interfaces. Physics modules read and write data through those common interfaces, which also provide access to common simulation services like parallel IO, mesh partitioning, etc.. Multi-physics codes are assembled as a combination of physics modules, services, interface implementations, and driver code which coordinates calling these various pieces. Examples of various physics modules and services connected to this framework are given. (author)

Modeling of Liquid Steel/Slag/Argon Gas Multiphase Flow During Tundish Open Eye Formation in a Two-Strand Tundish

Science.gov (United States)

Chatterjee, Saikat; Li, Donghui; Chattopadhyay, Kinnor

2018-04-01

Multiphase flows are frequently encountered in metallurgical operations. One of the most effective ways to understand these processes is by flow modeling. The process of tundish open eye (TOE) formation involves three-phase interaction between liquid steel, slag, and argon gas. The two-phase interaction involving argon gas bubbles and liquid steel can be modeled relatively easily using the discrete phase modeling technique. However, the effect of an upper slag layer cannot be captured using this approach. The presence of an upper buoyant phase can have a major effect on the behavior of TOEs. Hence, a multiphase model, including three phases, viz. liquid steel, slag, and argon gas, in a two-strand slab caster tundish, was developed to study the formation and evolution of TOEs. The volume of fluid model was used to track the interphase between liquid steel and slag phases, while the discrete phase model was used to trace the movement of the argon gas bubbles in liquid steel. The variation in the TOE areas with different amounts of aspirated argon gas was examined in the presence of an overlying slag phase. The mathematical model predictions were compared against steel plant measurements.

Frontiers and progress in multiphase flow

CERN Document Server

2014-01-01

This volume presents state-of-the-art of reviews in the field of multiphase flow. In focusses on nonlinear aspects of multiphase flow networks as well as visualization experiments. The first chapter presents nonlinear aspects or deterministic chaos issues in the systems of multi-phase reactors.  The second chapter reviews two-phase flow dynamics in combination with complex network theory. The third chapter discusses evaporation mechanism in the wick of copper heat pipes. The last chapter investigates numerically the flow dynamics and heat and mass transfer in the laminar and turbulent boundary layer on the flat vertical plate.

Multi-phase flow monitoring with electrical impedance tomography using level set based method

International Nuclear Information System (INIS)

Liu, Dong; Khambampati, Anil Kumar; Kim, Sin; Kim, Kyung Youn

2015-01-01

Highlights: • LSM has been used for shape reconstruction to monitor multi-phase flow using EIT. • Multi-phase level set model for conductivity is represented by two level set functions. • LSM handles topological merging and breaking naturally during evolution process. • To reduce the computational time, a narrowband technique was applied. • Use of narrowband and optimization approach results in efficient and fast method. - Abstract: In this paper, a level set-based reconstruction scheme is applied to multi-phase flow monitoring using electrical impedance tomography (EIT). The proposed scheme involves applying a narrowband level set method to solve the inverse problem of finding the interface between the regions having different conductivity values. The multi-phase level set model for the conductivity distribution inside the domain is represented by two level set functions. The key principle of the level set-based method is to implicitly represent the shape of interface as the zero level set of higher dimensional function and then solve a set of partial differential equations. The level set-based scheme handles topological merging and breaking naturally during the evolution process. It also offers several advantages compared to traditional pixel-based approach. Level set-based method for multi-phase flow is tested with numerical and experimental data. It is found that level set-based method has better reconstruction performance when compared to pixel-based method

Analysis of hygral induced crack growth in multiphase materials

NARCIS (Netherlands)

Sadouki, H.; Van Mier, J.G.M.

1996-01-01

In this paper a numerical model for simulating crack growth processes caused by moisture movement in a porous multiphase material like concrete is proposed. In the model, the material is schematized as a regular triangular network of beam elements. The meso-material structure of the material is

3D Multiphysical Modelling of Fluid Dynamics and Mass Transfer in Laser Welding of Dissimilar Materials

Directory of Open Access Journals (Sweden)

Jiazhou Wu

2018-06-01

Full Text Available A three-dimensional multiphysical transient model was developed to investigate keyhole formation, weld pool dynamics, and mass transfer in laser welding of dissimilar materials. The coupling of heat transfer, fluid flow, keyhole free surface evolution, and solute diffusion between dissimilar metals was simulated. The adaptive heat source model was used to trace the change of keyhole shape, and the Rayleigh scattering of the laser beam was considered. The keyhole wall was calculated using the fluid volume equation, primarily considering the recoil pressure induced by metal evaporation, surface tension, and hydrostatic pressure. Fluid flow, diffusion, and keyhole formation were considered simultaneously in mass transport processes. Welding experiments of 304L stainless steel and industrial pure titanium TA2 were performed to verify the simulation results. It is shown that spatters are shaped during the welding process. The thickness of the intermetallic reaction layer between the two metals and the diffusion of elements in the weld are calculated, which are important criteria for welding quality. The simulation results correspond well with the experimental results.

Multi-phase chemistry in process simulation - MASIT04 (VISTA)

Energy Technology Data Exchange (ETDEWEB)

Brink, A.; Li Bingzhi; Hupa, M. (Aabo Akademi University, Combustion and Materials Chemistry, Turku (Finland)) (and others)

2008-07-01

A new generation of process models has been developed by using advanced multi-phase thermochemistry. The generality of the thermodynamic free energy concept enables use of common software tools for high and low temperature processes. Reactive multi-phase phenomena are integrated to advanced simulation procedures by using local equilibrium or constrained state free energy computation. The high-temperature applications include a process model for the heat recovery of copper flash smelting and coupled models for converter and bloom casting operations in steel-making. Wet suspension models are developed for boiler and desalination water chemistry, flash evaporation of black liquor and for selected fibre-line and paper-making processes. The simulation combines quantitative physical and chemical data from reactive flows to form their visual images, thus providing efficient tools for engineering design and industrial decision-making. Economic impacts are seen as both better process operations and improved end products. The software tools developed are internationally commercialised and being used to support Finnish process technology exports. (orig.)

Integral Full Core Multi-Physics PWR Benchmark with Measured Data

Energy Technology Data Exchange (ETDEWEB)

Forget, Benoit; Smith, Kord; Kumar, Shikhar; Rathbun, Miriam; Liang, Jingang

2018-04-11

In recent years, the importance of modeling and simulation has been highlighted extensively in the DOE research portfolio with concrete examples in nuclear engineering with the CASL and NEAMS programs. These research efforts and similar efforts worldwide aim at the development of high-fidelity multi-physics analysis tools for the simulation of current and next-generation nuclear power reactors. Like all analysis tools, verification and validation is essential to guarantee proper functioning of the software and methods employed. The current approach relies mainly on the validation of single physic phenomena (e.g. critical experiment, flow loops, etc.) and there is a lack of relevant multiphysics benchmark measurements that are necessary to validate high-fidelity methods being developed today. This work introduces a new multi-cycle full-core Pressurized Water Reactor (PWR) depletion benchmark based on two operational cycles of a commercial nuclear power plant that provides a detailed description of fuel assemblies, burnable absorbers, in-core fission detectors, core loading and re-loading patterns. This benchmark enables analysts to develop extremely detailed reactor core models that can be used for testing and validation of coupled neutron transport, thermal-hydraulics, and fuel isotopic depletion. The benchmark also provides measured reactor data for Hot Zero Power (HZP) physics tests, boron letdown curves, and three-dimensional in-core flux maps from 58 instrumented assemblies. The benchmark description is now available online and has been used by many groups. However, much work remains to be done on the quantification of uncertainties and modeling sensitivities. This work aims to address these deficiencies and make this benchmark a true non-proprietary international benchmark for the validation of high-fidelity tools. This report details the BEAVRS uncertainty quantification for the first two cycle of operations and serves as the final report of the project.

A survey of open source multiphysics frameworks in engineering

NARCIS (Netherlands)

Babur, O.; Smilauer, V.; Verhoeff, T.; Brand, van den M.G.J.

2015-01-01

This paper presents a systematic survey of open source multiphysics frameworks in the en- gineering domains. These domains share many commonalities despite the diverse application areas. A thorough search for the available frameworks with both academic and industrial ori- gins has revealed numerous

A Mathematical Model for the Multiphase Transport and Reaction Kinetics in a Ladle with Bottom Powder Injection

Science.gov (United States)

Lou, Wentao; Zhu, Miaoyong

2017-12-01

A computation fluid dynamics-population balance model-simultaneous reaction model (CFD-PBM-SRM) coupled model has been proposed to study the multiphase flow behavior and refining reaction kinetics in a ladle with bottom powder injection, and some new and important phenomena and mechanisms are presented. For the multiphase flow behavior, the effects of bubbly plume flow, powder particle motion, particle-particle collision and growth, particle-bubble collision and adhesion, and powder particle removal into top slag are considered. For the reaction kinetics, the mechanisms of multicomponent simultaneous reactions, including Al, S, Si, Mn, Fe, and O, at the multi-interface, including top slag-liquid steel interface, air-liquid steel interface, powder droplet-liquid steel interface, and bubble-liquid steel interface, are presented, and the effect of sulfur solubility in the powder droplet on the desulfurization is also taken into account. Model validation is carried out using hot tests in a 2-t induction furnace with bottom powder injection. The result shows that the powder particles gradually disperse in the entire furnace; in the vicinity of the bottom slot plugs, the desulfurization product CaS is liquid phase, while in the upper region of the furnace, the desulfurization product CaS is solid phase. The predicted sulfur contents by the present model agree well with the measured data in the 2-t furnace with bottom powder injection.

Multiphase modelling of mud volcanoes

Science.gov (United States)

Colucci, Simone; de'Michieli Vitturi, Mattia; Clarke, Amanda B.

2015-04-01

Mud volcanism is a worldwide phenomenon, classically considered as the surface expression of piercement structures rooted in deep-seated over-pressured sediments in compressional tectonic settings. The release of fluids at mud volcanoes during repeated explosive episodes has been documented at numerous sites and the outflows resemble the eruption of basaltic magma. As magma, the material erupted from a mud volcano becomes more fluid and degasses while rising and decompressing. The release of those gases from mud volcanism is estimated to be a significant contributor both to fluid flux from the lithosphere to the hydrosphere, and to the atmospheric budget of some greenhouse gases, particularly methane. For these reasons, we simulated the fluid dynamics of mud volcanoes using a newly-developed compressible multiphase and multidimensional transient solver in the OpenFOAM framework, taking into account the multicomponent nature (CH4, CO2, H2O) of the fluid mixture, the gas exsolution during the ascent and the associated changes in the constitutive properties of the phases. The numerical model has been tested with conditions representative of the LUSI, a mud volcano that has been erupting since May 2006 in the densely populated Sidoarjo regency (East Java, Indonesia), forcing the evacuation of 40,000 people and destroying industry, farmland, and over 10,000 homes. The activity of LUSI mud volcano has been well documented (Vanderkluysen et al., 2014) and here we present a comparison of observed gas fluxes and mud extrusion rates with the outcomes of numerical simulations. Vanderkluysen, L.; Burton, M. R.; Clarke, A. B.; Hartnett, H. E. & Smekens, J.-F. Composition and flux of explosive gas release at LUSI mud volcano (East Java, Indonesia) Geochem. Geophys. Geosyst., Wiley-Blackwell, 2014, 15, 2932-2946

Crystallographically based model for transformation-induced plasticity in multiphase carbon steels

NARCIS (Netherlands)

Tjahjanto, D.D.; Turteltaub, S.; Suiker, A.S.J.

2007-01-01

The microstructure of multiphase steels assisted by transformation-induced plasticity consists of grains of retained austenite embedded in a ferrite-based matrix. Upon mechanical loading, retained austenite may transform into martensite, as a result of which plastic deformations are induced in the

Crystallographically based model for transformation-induced plasticity in multiphase carbon steels

NARCIS (Netherlands)

Tjahjanto, D.D.; Turteltaub, S.R.; Suiker, A.S.J.

2008-01-01

The microstructure of multiphase steels assisted by transformation-induced plasticity consists of grains of retained austenite embedded in a ferrite-based matrix. Upon mechanical loading, retained austenite may transform into martensite, as a result of which plastic deformations are induced in the

Non-Equilibrium Thermodynamics in Multiphase Flows

CERN Document Server

Mauri, Roberto

2013-01-01

Non-equilibrium thermodynamics is a general framework that allows the macroscopic description of irreversible processes. This book introduces non-equilibrium thermodynamics and its applications to the rheology of multiphase flows. The subject is relevant to graduate students in chemical and mechanical engineering, physics and material science. This book is divided into two parts. The first part presents the theory of non-equilibrium thermodynamics, reviewing its essential features and showing, when possible, some applications. The second part of this book deals with how the general theory can be applied to model multiphase flows and, in particular, how to determine their constitutive relations. Each chapter contains problems at the end, the solutions of which are given at the end of the book. No prior knowledge of statistical mechanics is required; the necessary prerequisites are elements of transport phenomena and on thermodynamics. “The style of the book is mathematical, but nonetheless it remains very re...

Multiphase flow models for hydraulic fracturing technology

Science.gov (United States)

Osiptsov, Andrei A.

2017-10-01

drift-flux approaches. The derivation of the drift-flux model from conservation olaws is criticall revisited in order to define the list of underlying assumptions and to mark the applicability margins of the model. All these fundamental problems share the same technological application (hydraulic fracturing) and the same method of research, namely, the multi-fluid approach to multiphase flow modeling and the consistent use of asymptotic methods. Multi-fluid models are then discussed in comparison with semi-empirical (often postulated) models widely used in the industry.

Multiphase forces on bend structures – critical gas fraction for transition single phase gas to multiphase flow behaviour

NARCIS (Netherlands)

Belfroid, S.P.C.; Nennie, E.D.; Lewis, M.

2016-01-01

Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum

On multiphase negative flash for ideal solutions

DEFF Research Database (Denmark)

Yan, Wei; Stenby, Erling Halfdan

2012-01-01

simpler than the corresponding normal flash algorithm. Unlike normal flash, multiphase negative flash for ideal solutions can diverge if the feasible domain for phase amounts is not closed. This can be judged readily during the iteration process. The algorithm can also be extended to the partial negative......There is a recent interest to solve multiphase negative flash problems where the phase amounts can be negative for normal positive feed composition. Solving such a negative flash problem using successive substitution needs an inner loop for phase distribution calculation at constant fugacity...... coefficients. It is shown that this inner loop, named here as multiphase negative flash for ideal solutions, can be solved either by Michelsen's algorithm for multiphase normal flash, or by its variation which uses F−1 phase amounts as independent variables. In either case, the resulting algorithm is actually...

Investigation of free vibration characteristics for skew multiphase magneto-electro-elastic plate

Science.gov (United States)

Kiran, M. C.; Kattimani, S.

2018-04-01

This article presents the investigation of skew multiphase magneto-electro-elastic (MMEE) plate to assess its free vibration characteristics. A finite element (FE) model is formulated considering the different couplings involved via coupled constitutive equations. The transformation matrices are derived to transform local degrees of freedom into the global degrees of freedom for the nodes lying on the skew edges. Effect of different volume fraction (Vf) on the free vibration behavior is explicitly studied. In addition, influence of width to thickness ratio, the aspect ratio, and the stacking arrangement on natural frequencies of skew multiphase MEE plate investigated. Particular attention has been paid to investigate the effect of skew angle on the non-dimensional Eigen frequencies of multiphase MEE plate with simply supported edges.

Advances in multiphase flow and related problems

International Nuclear Information System (INIS)

Papanicolaou, G.

1986-01-01

Proceedings of a workshop in multiphase flow held at Leesburg, Va. in June 1986 representing a cross-disciplinary approach to theoretical as well as computational problems in multiphase flow. Topics include composites, phase transitions, fluid-particle systems, and bubbly liquids

Modelling multiphase flow inside the porous media of a polymer electrolyte membrane fuel cell

DEFF Research Database (Denmark)

Berning, Torsten; Kær, Søren Knudsen

2011-01-01

Transport processes inside polymer electrolyte membrane fuel cells (PEMFC’s) are highly complex and involve convective and diffusive multiphase, multispecies flow through porous media along with heat and mass transfer and electrochemical reactions in conjunction with water transport through...... an electrolyte membrane. We will present a computational model of a PEMFC with focus on capillary transport of water through the porous layers and phase change and discuss the impact of the liquid phase boundary condition between the porous gas diffusion layer and the flow channels, where water droplets can...

Development of Next Generation Multiphase Pipe Flow Prediction Tools

Energy Technology Data Exchange (ETDEWEB)

Tulsa Fluid Flow

2008-08-31

The developments of fields in deep waters (5000 ft and more) is a common occurrence. It is inevitable that production systems will operate under multiphase flow conditions (simultaneous flow of gas-oil-and water possibly along with sand, hydrates, and waxes). Multiphase flow prediction tools are essential for every phase of the hydrocarbon recovery from design to operation. The recovery from deep-waters poses special challenges and requires accurate multiphase flow predictive tools for several applications including the design and diagnostics of the production systems, separation of phases in horizontal wells, and multiphase separation (topside, seabed or bottom-hole). It is very crucial to any multiphase separation technique that is employed either at topside, seabed or bottom-hole to know inlet conditions such as the flow rates, flow patterns, and volume fractions of gas, oil and water coming into the separation devices. The overall objective was to develop a unified model for gas-oil-water three-phase flow in wells, flow lines, and pipelines to predict the flow characteristics such as flow patterns, phase distributions, and pressure gradient encountered during petroleum production at different flow conditions (pipe diameter and inclination, fluid properties and flow rates). The project was conducted in two periods. In Period 1 (four years), gas-oil-water flow in pipes were investigated to understand the fundamental physical mechanisms describing the interaction between the gas-oil-water phases under flowing conditions, and a unified model was developed utilizing a novel modeling approach. A gas-oil-water pipe flow database including field and laboratory data was formed in Period 2 (one year). The database was utilized in model performance demonstration. Period 1 primarily consisted of the development of a unified model and software to predict the gas-oil-water flow, and experimental studies of the gas-oil-water project, including flow behavior description and

Models of thermal transfer by radiation and by conduction, in any geometry, in multiphase multicomponent medium

International Nuclear Information System (INIS)

Jeanne, T.

1990-03-01

A conduction model and a radiation model are proposed for the calculation of heat transfer. A multiphase multicomponent medium is considered. The conduction model allows the calculation of heat exchanges between two configurations. The heat flow from each component can be obtained. This model is well adapted to the calculation of thermal shocks in an ensemble of materials. The radiation model shows how the radiative transfers can be calculated in a cylinder composed of two opaque surfaces, with the same axis of rotation, and separated by a transparent medium. The form factors are obtained from Herman and Nusselt methods. The parts of the face-to-face surfaces which are seen and not seen are evaluated [fr

DENSE MULTIPHASE FLOW SIMULATION: CONTINUUM MODEL FOR POLY-DISPERSED SYSTEMS USING KINETIC THEORY

Energy Technology Data Exchange (ETDEWEB)

Moses Bogere

2011-08-31

The overall objective of the project was to verify the applicability of the FCMOM approach to the kinetic equations describing the particle flow dynamics. For monodispersed systems the fundamental equation governing the particle flow dynamics is the Boltzmann equation. During the project, the FCMOM was successfully applied to several homogeneous and in-homogeneous problems in different flow regimes, demonstrating that the FCMOM has the potential to be used to solve efficiently the Boltzmann equation. However, some relevant issues still need to be resolved, i.e. the homogeneous cooling problem (inelastic particles cases) and the transition between different regimes. In this report, the results obtained in homogeneous conditions are discussed first. Then a discussion of the validation results for in-homogeneous conditions is provided. And finally, a discussion will be provided about the transition between different regimes. Alongside the work on development of FCMOM approach studies were undertaken in order to provide insights into anisotropy or particles kinetics in riser hydrodynamics. This report includes results of studies of multiphase flow with unequal granular temperatures and analysis of momentum re-distribution in risers due to particle-particle and fluid-particle interactions. The study of multiphase flow with unequal granular temperatures entailed both simulation and experimental studies of two particles sizes in a riser and, a brief discussion of what was accomplished will be provided. And finally, a discussion of the analysis done on momentum re-distribution of gas-particles flow in risers will be provided. In particular a discussion of the remaining work needed in order to improve accuracy and predictability of riser hydrodynamics based on two-fluid models and how they can be used to model segregation in risers.

An open-source toolbox for multiphase flow in porous media

Science.gov (United States)

Horgue, P.; Soulaine, C.; Franc, J.; Guibert, R.; Debenest, G.

2015-02-01

Multiphase flow in porous media provides a wide range of applications: from the environmental understanding (aquifer, site-pollution) to industrial process improvements (oil production, waste management). Modeling of such flows involves specific volume-averaged equations and therefore specific computational fluid dynamics (CFD) tools. In this work, we develop a toolbox for modeling multiphase flow in porous media with OpenFOAM®, an open-source platform for CFD. The underlying idea of this approach is to provide an easily adaptable tool that can be used in further studies to test new mathematical models or numerical methods. The package provides the most common effective properties models of the literature (relative permeability, capillary pressure) and specific boundary conditions related to porous media flows. To validate this package, solvers based on the IMplicit Pressure Explicit Saturation (IMPES) method are developed in the toolbox. The numerical validation is performed by comparison with analytical solutions on academic cases. Then, a satisfactory parallel efficiency of the solver is shown on a more complex configuration.

Multiphase evolution of population and its application to optics and colliding-beam experiments

International Nuclear Information System (INIS)

Srinivasan, S.K.; Sridharan, V.

1990-01-01

In this paper we have analysed a multiphase evolution of population growth. Individual birth and immigration are assumed to be the consequence of the evolution of an individual through a sequence of phases whose duration form a family of independent non-negative random variables. The population model is then adapted to describe the evolution of photons in a cavity and, in particular, it is shown that a multiphase immigration model corresponds to the photons resulting from a stream obtained by amplitude mixing of coherent and chaotic beams. The model is also shown to bring out the characteristics of the multiplicity distribution of particles produced in high-energy collisions. (author)

Electrical capacitance tomography (ECT) and gamma radiation meter for comparison with and validation and tuning of computational fluid dynamics (CFD) modeling of multiphase flow

International Nuclear Information System (INIS)

Pradeep, Chaminda; Yan, Ru; Mylvaganam, Saba; Vestøl, Sondre; Melaaen, Morten C

2014-01-01

The electrical capacitance tomographic (ECT) approach is increasingly seen as attractive for measurement and control applications in the process industries. Recently, there is increased interest in using the tomographic details from ECT for comparing with and validating and tuning CFD models of multiphase flow. Collaboration with researchers working in the field of computational fluid dynamics (CFD) modeling of multiphase flows gives valuable information for both groups of researchers in the field of ECT and CFD. By studying the ECT tomograms of multiphase flows under carefully monitored inflow conditions of the different media and by obtaining the capacitance values, C(i, j, t) with i = 1…N, j = 1, 2,…N and i ≠ j obtained from ECT modules with N electrodes, it is shown how the interface heights in a pipe with stratified flow of oil and air can be fruitfully compared to the values of those obtained from ECT and gamma radiation meter (GRM) for improving CFD modeling. Monitored inflow conditions in this study are flow rates of air, water and oil into a pipe which can be positioned at varying inclinations to the horizontal, thus emulating the pipelines laid in subsea installations. It is found that ECT-based tomograms show most of the features seen in the GRM-based visualizations with nearly one-to-one correspondence to interface heights obtained from these two methods, albeit some anomalies at the pipe wall. However, there are some interesting features the ECT manages to capture: features which the GRM or the CFD modeling apparently do not show, possibly due to parameters not defined in the inputs to the CFD model or much slower response of the GRM. Results presented in this paper indicate that a combination of ECT and GRM and preferably with other modalities with enhanced data fusion and analysis combined with CFD modeling can help to improve the modeling, measurement and control of multiphase flow in the oil and gas industries and in the process industries

An incompressible two-dimensional multiphase particle-in-cell model for dense particle flows

Energy Technology Data Exchange (ETDEWEB)

Snider, D.M. [SAIC, Albuquerque, NM (United States); O`Rourke, P.J. [Los Alamos National Lab., NM (United States); Andrews, M.J. [Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering

1997-06-01

A two-dimensional, incompressible, multiphase particle-in-cell (MP-PIC) method is presented for dense particle flows. The numerical technique solves the governing equations of the fluid phase using a continuum model and those of the particle phase using a Lagrangian model. Difficulties associated with calculating interparticle interactions for dense particle flows with volume fractions above 5% have been eliminated by mapping particle properties to a Eulerian grid and then mapping back computed stress tensors to particle positions. This approach utilizes the best of Eulerian/Eulerian continuum models and Eulerian/Lagrangian discrete models. The solution scheme allows for distributions of types, sizes, and density of particles, with no numerical diffusion from the Lagrangian particle calculations. The computational method is implicit with respect to pressure, velocity, and volume fraction in the continuum solution thus avoiding courant limits on computational time advancement. MP-PIC simulations are compared with one-dimensional problems that have analytical solutions and with two-dimensional problems for which there are experimental data.

Measurement Of Multiphase Flow Water Fraction And Water-cut

Science.gov (United States)

Xie, Cheng-gang

2007-06-01

This paper describes a microwave transmission multiphase flow water-cut meter that measures the amplitude attenuation and phase shift across a pipe diameter at multiple frequencies using cavity-backed antennas. The multiphase flow mixture permittivity and conductivity are derived from a unified microwave transmission model for both water- and oil-continuous flows over a wide water-conductivity range; this is far beyond the capability of microwave-resonance-based sensors currently on the market. The water fraction and water cut are derived from a three-component gas-oil-water mixing model using the mixture permittivity or the mixture conductivity and an independently measured mixture density. Water salinity variations caused, for example, by changing formation water or formation/injection water breakthrough can be detected and corrected using an online water-conductivity tracking technique based on the interpretation of the mixture permittivity and conductivity, simultaneously measured by a single-modality microwave sensor.

A review of spurious currents in the lattice Boltzmann method for multiphase flows

Energy Technology Data Exchange (ETDEWEB)

Conning Ton, Kevin; Lee, Tae Hun [The City College of the City Univ. of New York, New York (United States)

2012-12-15

A spurious current is a small amplitude artificial velocity field which arises from an imbalance between discretized forces in multiphase/multi component flows. If it occurs, the velocity field may persist indefinitely, preventing the achievement of a true equilibrium state. Spurious velocities can sometimes be as large as the characteristic velocities of the problem, causing severe instability and ambiguity between physical and spurious velocities. They are typically exacerbated by large values of numerical surface tension or when the two fluids being simulated have large density ratios. The resulting instability can restrict what parameters may be simulated. To varying degrees, spurious currents are found in all multiphase flow models of the lattice Boltzmann method (LBM). There have been many studies of the occurrence of the phenomenon, and many suggestions on how to eliminate it. This paper reviews the three main models of simulating multiphase/multi component flow in the lattice Boltzmann method, as well as the subsequent modifications made in order to reduce or eliminate spurious currents.

Is it possible to design universal multi-phase flow analyzer?

International Nuclear Information System (INIS)

Ivanov Kolev, N.

2005-01-01

Transient 3D-multiphase flows consisting of many chemical constituents in nature and technology (Figs. 1 and 2) are the common case of flows. In many technical applications we have to do with particular realization of the multi-phase flows like steady state flows, or single component flows or single phase flows etc. Engineers and scientists created hundreds of computer codes for description of more or less specific realizations of multi-phase flows. If one compares the structure of these codes one is astonished by the waste of the human resources for programming repeating model elements like equations of state, friction lows in variety of geometry, heat transfer coefficients, mathematical equation solvers, data handling procedures, graphical environment etc. It is hardly to expect, that the best solution for the specific sub-phenomenon is available in all codes. Looking in other branches of the technology like computer chips production we realize that the revolutionary idea of having common ''chips'' within complex applications is very far from its practical realization in the computational multi-phase flow dynamics. Following this line of arguments I expressed several times in my publications explicitly or implicitly the idea, that it is possible to create a universal multi-phase flow analyzer in the sense of computer architecture, that is capable to absorb the adequate multi-phase knowledge data base specified in Appendix 1. The subject of this paper is to summarize some of the main ideas, some of them already realized by this author, on the way of creating such computer code architecture, to illustrate haw they work, and to make an outlook regarding what are the challenges in the future developments. We confine deliberately our attention to the solution of the so called local volume and time averaged system of PDE's for a simple reason: Direct numerical resolution of interacting fluids is possible as demonstrated for small scales by many researchers, but for

Technical Report on NETL's Non Newtonian Multiphase Slurry Workshop: A path forward to understanding non-Newtonian multiphase slurry flows

Energy Technology Data Exchange (ETDEWEB)

Guenther, Chris [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Garg, Rahul [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

2013-08-19

The Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) sponsored a workshop on non-Newtonian multiphase slurry at NETL’s Morgantown campus August 19 and 20, 2013. The objective of this special two-day meeting of 20-30 invited experts from industry, National Labs and academia was to identify and address technical issues associated with handling non-Newtonian multiphase slurries across various facilities managed by DOE. Particular emphasis during this workshop was placed on applications managed by the Office of Environmental Management (EM). The workshop was preceded by two webinars wherein personnel from ORP and NETL provided background information on the Hanford WTP project and discussed the critical design challenges facing this project. In non-Newtonian fluids, viscosity is not constant and exhibits a complex dependence on applied shear stress or deformation. Many applications under EM’s tank farm mission involve non-Newtonian slurries that are multiphase in nature; tank farm storage and handling, slurry transport, and mixing all involve multiphase flow dynamics, which require an improved understanding of the mechanisms responsible for rheological changes in non-Newtonian multiphase slurries (NNMS). To discuss the issues in predicting the behavior of NNMS, the workshop focused on two topic areas: (1) State-of-the-art in non-Newtonian Multiphase Slurry Flow, and (2) Scaling up with Confidence and Ensuring Safe and Reliable Long-Term Operation.

Modular ORIGEN-S for multi-physics code systems

Energy Technology Data Exchange (ETDEWEB)

Yesilyurt, Gokhan; Clarno, Kevin T.; Gauld, Ian C., E-mail: yesilyurtg@ornl.gov, E-mail: clarnokt@ornl.gov, E-mail: gauldi@ornl.gov [Oak Ridge National Laboratory, TN (United States); Galloway, Jack, E-mail: jack@galloways.net [Los Alamos National Laboratory, Los Alamos, NM (United States)

2011-07-01

The ORIGEN-S code in the SCALE 6.0 nuclear analysis code suite is a well-validated tool to calculate the time-dependent concentrations of nuclides due to isotopic depletion, decay, and transmutation for many systems in a wide range of time scales. Application areas include nuclear reactor and spent fuel storage analyses, burnup credit evaluations, decay heat calculations, and environmental assessments. Although simple to use within the SCALE 6.0 code system, especially with the ORIGEN-ARP graphical user interface, it is generally complex to use as a component within an externally developed code suite because of its tight coupling within the infrastructure of the larger SCALE 6.0 system. The ORIGEN2 code, which has been widely integrated within other simulation suites, is no longer maintained by Oak Ridge National Laboratory (ORNL), has obsolete data, and has a relatively small validation database. Therefore, a modular version of the SCALE/ORIGEN-S code was developed to simplify its integration with other software packages to allow multi-physics nuclear code systems to easily incorporate the well-validated isotopic depletion, decay, and transmutation capability to perform realistic nuclear reactor and fuel simulations. SCALE/ORIGEN-S was extensively restructured to develop a modular version that allows direct access to the matrix solvers embedded in the code. Problem initialization and the solver were segregated to provide a simple application program interface and fewer input/output operations for the multi-physics nuclear code systems. Furthermore, new interfaces were implemented to access and modify the ORIGEN-S input variables and nuclear cross-section data through external drivers. Three example drivers were implemented, in the C, C++, and Fortran 90 programming languages, to demonstrate the modular use of the new capability. This modular version of SCALE/ORIGEN-S has been embedded within several multi-physics software development projects at ORNL, including

Modular ORIGEN-S for multi-physics code systems

International Nuclear Information System (INIS)

Yesilyurt, Gokhan; Clarno, Kevin T.; Gauld, Ian C.; Galloway, Jack

2011-01-01

The ORIGEN-S code in the SCALE 6.0 nuclear analysis code suite is a well-validated tool to calculate the time-dependent concentrations of nuclides due to isotopic depletion, decay, and transmutation for many systems in a wide range of time scales. Application areas include nuclear reactor and spent fuel storage analyses, burnup credit evaluations, decay heat calculations, and environmental assessments. Although simple to use within the SCALE 6.0 code system, especially with the ORIGEN-ARP graphical user interface, it is generally complex to use as a component within an externally developed code suite because of its tight coupling within the infrastructure of the larger SCALE 6.0 system. The ORIGEN2 code, which has been widely integrated within other simulation suites, is no longer maintained by Oak Ridge National Laboratory (ORNL), has obsolete data, and has a relatively small validation database. Therefore, a modular version of the SCALE/ORIGEN-S code was developed to simplify its integration with other software packages to allow multi-physics nuclear code systems to easily incorporate the well-validated isotopic depletion, decay, and transmutation capability to perform realistic nuclear reactor and fuel simulations. SCALE/ORIGEN-S was extensively restructured to develop a modular version that allows direct access to the matrix solvers embedded in the code. Problem initialization and the solver were segregated to provide a simple application program interface and fewer input/output operations for the multi-physics nuclear code systems. Furthermore, new interfaces were implemented to access and modify the ORIGEN-S input variables and nuclear cross-section data through external drivers. Three example drivers were implemented, in the C, C++, and Fortran 90 programming languages, to demonstrate the modular use of the new capability. This modular version of SCALE/ORIGEN-S has been embedded within several multi-physics software development projects at ORNL, including

Grain size effects in multiphase steels assisted by transformation-induced plasticity

NARCIS (Netherlands)

Turteltaub, S.R.; Suiker, A.S.J.

2006-01-01

The influence of the austenitic grain size on the overall stress-strain behavior in a multiphase carbon steel is analyzed through three-dimensional finite element simulations. A recently developed multiscale martensitic transformation model is combined with a plasticity model to simulate the

Computational Modeling of Arc-Slag Interaction in DC Furnaces

Science.gov (United States)

Reynolds, Quinn G.

2017-02-01

The plasma arc is central to the operation of the direct-current arc furnace, a unit operation commonly used in high-temperature processing of both primary ores and recycled metals. The arc is a high-velocity, high-temperature jet of ionized gas created and sustained by interactions among the thermal, momentum, and electromagnetic fields resulting from the passage of electric current. In addition to being the primary source of thermal energy, the arc jet also couples mechanically with the bath of molten process material within the furnace, causing substantial splashing and stirring in the region in which it impinges. The arc's interaction with the molten bath inside the furnace is studied through use of a multiphase, multiphysics computational magnetohydrodynamic model developed in the OpenFOAM® framework. Results from the computational solver are compared with empirical correlations that account for arc-slag interaction effects.

Advanced multi-physics simulation capability for very high temperature reactors

International Nuclear Information System (INIS)

Lee, Hyun Chul; Tak, Nam Il; Jo Chang Keun; Noh, Jae Man; Cho, Bong Hyun; Cho, Jin Woung; Hong, Ser Gi

2012-01-01

The purpose of this research is to develop methodologies and computer code for high-fidelity multi-physics analysis of very high temperature gas-cooled reactors(VHTRs). The research project was performed through Korea-US I-NERI program. The main research topic was development of methodologies for high-fidelity 3-D whole core transport calculation, development of DeCART code for VHTR reactor physics analysis, generation of VHTR specific 190-group cross-section library for DeCART code, development of DeCART/CORONA coupled code system for neutronics/thermo-fluid multi-physics analysis, and benchmark analysis against various benchmark problems derived from PMR200 reactor. The methodologies and the code systems will be utilized a key technologies in the Nuclear Hydrogen Development and Demonstration program. Export of code system is expected in the near future and the code systems developed in this project are expected to contribute to development and export of nuclear hydrogen production system

Multi-Physics Demonstration Problem with the SHARP Reactor Simulation Toolkit

Energy Technology Data Exchange (ETDEWEB)

Merzari, E. [Argonne National Lab. (ANL), Argonne, IL (United States); Shemon, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States); Yu, Y. Q. [Argonne National Lab. (ANL), Argonne, IL (United States); Thomas, J. W. [Argonne National Lab. (ANL), Argonne, IL (United States); Obabko, A. [Argonne National Lab. (ANL), Argonne, IL (United States); Jain, Rajeev [Argonne National Lab. (ANL), Argonne, IL (United States); Mahadevan, Vijay [Argonne National Lab. (ANL), Argonne, IL (United States); Tautges, Timothy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Solberg, Jerome [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ferencz, Robert Mark [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Whitesides, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-12-21

This report describes to employ SHARP to perform a first-of-a-kind analysis of the core radial expansion phenomenon in an SFR. This effort required significant advances in the framework Multi-Physics Demonstration Problem with the SHARP Reactor Simulation Toolkit used to drive the coupled simulations, manipulate the mesh in response to the deformation of the geometry, and generate the necessary modified mesh files. Furthermore, the model geometry is fairly complex, and consistent mesh generation for the three physics modules required significant effort. Fully-integrated simulations of a 7-assembly mini-core test problem have been performed, and the results are presented here. Physics models of a full-core model of the Advanced Burner Test Reactor have also been developed for each of the three physics modules. Standalone results of each of the three physics modules for the ABTR are presented here, which provides a demonstration of the feasibility of the fully-integrated simulation.

Multiscale multiphysics and multidomain models—Flexibility and rigidity

International Nuclear Information System (INIS)

Xia, Kelin; Opron, Kristopher; Wei, Guo-Wei

2013-01-01

The emerging complexity of large macromolecules has led to challenges in their full scale theoretical description and computer simulation. Multiscale multiphysics and multidomain models have been introduced to reduce the number of degrees of freedom while maintaining modeling accuracy and achieving computational efficiency. A total energy functional is constructed to put energies for polar and nonpolar solvation, chemical potential, fluid flow, molecular mechanics, and elastic dynamics on an equal footing. The variational principle is utilized to derive coupled governing equations for the above mentioned multiphysical descriptions. Among these governing equations is the Poisson-Boltzmann equation which describes continuum electrostatics with atomic charges. The present work introduces the theory of continuum elasticity with atomic rigidity (CEWAR). The essence of CEWAR is to formulate the shear modulus as a continuous function of atomic rigidity. As a result, the dynamics complexity of a macromolecular system is separated from its static complexity so that the more time-consuming dynamics is handled with continuum elasticity theory, while the less time-consuming static analysis is pursued with atomic approaches. We propose a simple method, flexibility-rigidity index (FRI), to analyze macromolecular flexibility and rigidity in atomic detail. The construction of FRI relies on the fundamental assumption that protein functions, such as flexibility, rigidity, and energy, are entirely determined by the structure of the protein and its environment, although the structure is in turn determined by all the interactions. As such, the FRI measures the topological connectivity of protein atoms or residues and characterizes the geometric compactness of the protein structure. As a consequence, the FRI does not resort to the interaction Hamiltonian and bypasses matrix diagonalization, which underpins most other flexibility analysis methods. FRI's computational complexity is of O

Advanced subgrid modeling for Multiphase CFD in CASL VERA tools

International Nuclear Information System (INIS)

Baglietto, Emilio; Gilman, Lindsey; Sugrue, Rosie

2014-01-01

This work introduces advanced modeling capabilities that are being developed to improve the accuracy and extend the applicability of Multiphase CFD. Specifics of the advanced and hardened boiling closure model are described in this work. The development has been driven by new physical understanding, derived from the innovative experimental techniques available at MIT. A new experimental-based mechanistic approach to heat partitioning is proposed. The model introduces a new description of the bubble evaporation, sliding and interaction on the heated surface to accurately capture the evaporation occurring at the heated surface, while also tracking the local surface conditions. The model is being assembled to cover an extended application area, up to Critical Heat Flux (CHF). The accurate description of the bubble interaction, effective microlayer and dry surface area are considered to be the enabling quantities towards innovated CHF capturing methodologies. Further, improved mechanistic force-balance models for bubble departure predictions and lift-off diameter predictions are implemented in the model. Studies demonstrate the influence of the newly implemented partitioning components. Finally, the development work towards a more consistent and integrated hydrodynamic closure is presented. The main objective here is to develop a set of robust momentum closure relations which focuses on the specific application to PWR conditions, but will facilitate the application to other geometries, void fractions, and flow regimes. The innovative approach considers local flow conditions on a cell-by-cell basis to ensure robustness. Closure relations of interest initially include drag, lift, and turbulence dispersion, with near wall corrections applied for both drag and lift. (author)

Multiphysics simulation by design for electrical machines, power electronics and drives

CERN Document Server

Rosu, Marius; Lin, Dingsheng; Ionel, Dan M; Popescu, Mircea; Blaabjerg, Frede; Rallabandi, Vandana; Staton, David

2018-01-01

This book combines the knowledge of experts from both academia and the software industry to present theories of multiphysics simulation by design for electrical machines, power electronics, and drives. The comprehensive design approach described within supports new applications required by technologies sustaining high drive efficiency. The highlighted framework considers the electric machine at the heart of the entire electric drive. The book also emphasizes the simulation by design concept--a concept that frames the entire highlighted design methodology, which is described and illustrated by various advanced simulation technologies. Multiphysics Simulation by Design for Electrical Machines, Power Electronics and Drives begins with the basics of electrical machine design and manufacturing tolerances. It also discusses fundamental aspects of the state of the art design process and includes examples from industrial practice. It explains FEM-based analysis techniques for electrical machine design--providing deta...

Optimal Power Flow in Multiphase Radial Networks with Delta Connections: Preprint

Energy Technology Data Exchange (ETDEWEB)

Zhao, Changhong [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dall-Anese, Emiliano [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Low, Steven H. [California Institute of Technology

2017-11-27

This paper focuses on multiphase radial distribution networks with mixed wye and delta connections, and proposes a semidefinite relaxation of the AC optimal power flow (OPF) problem. Two multiphase power-flow models are developed to facilitate the integration of delta-connected generation units/loads in the OPF problem. The first model extends traditional branch flow models - and it is referred to as extended branch flow model (EBFM). The second model leverages a linear relationship between per-phase power injections and delta connections, which holds under a balanced voltage approximation (BVA). Based on these models, pertinent OPF problems are formulated and relaxed to semidefinite programs (SDPs). Numerical studies on IEEE test feeders show that SDP relaxations can be solved efficiently by a generic optimization solver. Numerical evidences indicate that solving the resultant SDP under BVA is faster than under EBFM. Moreover, both SDP solutions are numerically exact with respect to voltages and branch flows. It is also shown that the SDP solution under BVA has a small optimality gap, while the BVA model is accurate in the sense that it reflects actual system voltages.

Multiphasic on/off pheromone signalling in moths as neural correlates of a search strategy.

Directory of Open Access Journals (Sweden)

Dominique Martinez

Full Text Available Insects and robots searching for odour sources in turbulent plumes face the same problem: the random nature of mixing causes fluctuations and intermittency in perception. Pheromone-tracking male moths appear to deal with discontinuous flows of information by surging upwind, upon sensing a pheromone patch, and casting crosswind, upon losing the plume. Using a combination of neurophysiological recordings, computational modelling and experiments with a cyborg, we propose a neuronal mechanism that promotes a behavioural switch between surge and casting. We show how multiphasic On/Off pheromone-sensitive neurons may guide action selection based on signalling presence or loss of the pheromone. A Hodgkin-Huxley-type neuron model with a small-conductance calcium-activated potassium (SK channel reproduces physiological On/Off responses. Using this model as a command neuron and the antennae of tethered moths as pheromone sensors, we demonstrate the efficiency of multiphasic patterning in driving a robotic searcher toward the source. Taken together, our results suggest that multiphasic On/Off responses may mediate olfactory navigation and that SK channels may account for these responses.

Multiphasic on/off pheromone signalling in moths as neural correlates of a search strategy.

Science.gov (United States)

Martinez, Dominique; Chaffiol, Antoine; Voges, Nicole; Gu, Yuqiao; Anton, Sylvia; Rospars, Jean-Pierre; Lucas, Philippe

2013-01-01

Insects and robots searching for odour sources in turbulent plumes face the same problem: the random nature of mixing causes fluctuations and intermittency in perception. Pheromone-tracking male moths appear to deal with discontinuous flows of information by surging upwind, upon sensing a pheromone patch, and casting crosswind, upon losing the plume. Using a combination of neurophysiological recordings, computational modelling and experiments with a cyborg, we propose a neuronal mechanism that promotes a behavioural switch between surge and casting. We show how multiphasic On/Off pheromone-sensitive neurons may guide action selection based on signalling presence or loss of the pheromone. A Hodgkin-Huxley-type neuron model with a small-conductance calcium-activated potassium (SK) channel reproduces physiological On/Off responses. Using this model as a command neuron and the antennae of tethered moths as pheromone sensors, we demonstrate the efficiency of multiphasic patterning in driving a robotic searcher toward the source. Taken together, our results suggest that multiphasic On/Off responses may mediate olfactory navigation and that SK channels may account for these responses.

Fully coupled modeling of burnup dependent light water reactor fuel performance using COMSOL Multiphysics

International Nuclear Information System (INIS)

Liu Rong; Zhou Wenzhong; Prudil, Andrew

2015-01-01

This paper presents the development of a light water reactor fuel performance code, which considers almost all the related physical models, including heat generation and conduction, species diffusion, thermomechanics (thermal expansion, elastic strain, densification, and fission product swelling strain), grain growth, fission gas production and release, gap heat transfer, mechanical contact, gap/plenum pressure with plenum volume, cladding thermal and irradiation creep and oxidation. All the equations are implemented into COMSOL Multiphysics finite-element platform with a 2D axisymmetric geometry of a fuel pellet and cladding. Comparisons are made for the simulation results between COMSOL and another simulation tool of BISON. The comparisons show the capability of our simulation tool to predict light water UO 2 fuel performances. In our modeling and simulation work, the performance of enhanced thermal conductivity UO 2 -BeO fuel and newly-adopted corrosion resistant SiC cladding material was also studied. UO 2 -BeO high thermal conductivity nuclear fuel would decrease fuel temperatures and facilitate a reduction in pellet cladding interaction through lessening thermal stresses that result in fuel cracking, relocation, and swelling. The safety of the reactor would be improved. However, for SiC cladding, although due to its high thermal expansion, the gap closure time is delayed, irradiation induced point defects and defect-clusters in the SiC crystal will dramatically decrease SiC thermal conductivity, and cause significant increase in the fuel temperature. (author)

Development and Research of Peristaltic Multiphase Piezoelectric Micro-Pump

Science.gov (United States)

Vinogradov, Alexander N.; Ivanikin, Igor A.; Lubchenco, Roman V.; Matveev, Yegor V.; Titov, Pavel A.

2016-01-01

The paper presents the results of a study of existing models and mathematical representations of a range of truly peristaltic multiphase micro-pumps with a piezoelectric actuator (piezo drive). Piezo drives with different types of substrates use vertical movements at deformation of individual piezoelectric elements, which define device…

Developing a multi-physics solver in APOLLO3 and applications to cross section homogenization

International Nuclear Information System (INIS)

Dugan, Kevin-James

2016-01-01

Multi-physics coupling is becoming of large interest in the nuclear engineering and computational science fields. The ability to obtain accurate solutions to realistic models is important to the design and licensing of novel reactor designs, especially in design basis accident situations. The physical models involved in calculating accident behavior in nuclear reactors includes: neutron transport, thermal conduction/convection, thermo-mechanics in fuel and support structure, fuel stoichiometry, among others. However, this thesis focuses on the coupling between two models, neutron transport and thermal conduction/convection.The goal of this thesis is to develop a multi-physics solver for simulating accidents in nuclear reactors. The focus is both on the simulation environment and the data treatment used in such simulations.This work discusses the development of a multi-physics framework based around the Jacobian-Free Newton-Krylov (JFNK) method. The framework includes linear and nonlinear solvers, along with interfaces to existing numerical codes that solve neutron transport and thermal hydraulics models (APOLLO3 and MCTH respectively) through the computation of residuals. a new formulation for the neutron transport residual is explored, which reduces the solution size and search space by a large factor; instead of the residual being based on the angular flux, it is based on the fission source.The question of whether using a fundamental mode distribution of the neutron flux for cross section homogenization is sufficiently accurate during fast transients is also explored. It is shown that in an infinite homogeneous medium, using homogenized cross sections produced with a fundamental mode flux differ significantly from a reference solution. The error is remedied by using an alternative weighting flux taken from a time dependent calculation; either a time-integrated flux or an asymptotic solution. The time-integrated flux comes from the multi-physics solution of the

Industrial applications of multi-functional, multi-phase reactors

NARCIS (Netherlands)

Harmsen, G.J.; Chewter, L.A.

1999-01-01

To reveal trends in the design and operation of multi-functional, multi-phase reactors, this paper describes, in historical sequence, three industrial applications of multi-functional, multi-phase reactors developed and operated by Shell Chemicals during the last five decades. For each case, we

Prediction of Separation Length of Turbulent Multiphase Flow Using Radiotracer and Computational Fluid Dynamics Simulation

International Nuclear Information System (INIS)

Sugiharto, S.; Kurniadi, R.; Abidin, Z.; Stegowski, Z.; Furman, L.

2013-01-01

Multiphase flow modeling presents great challenges due to its extreme importance in various industrial and environmental applications. In the present study, prediction of separation length of multiphase flow is examined experimentally by injection of two kinds of iodine-based radiotracer solutions into a hydrocarbon transport pipeline (HCT) having an inner diameter of 24 in (60,96 m). The main components of fluids in the pipeline are water 95%, crude oil 3% and gas 2%. A radiotracing experiment was carried out at the segment of pipe which is located far from branch points with assumptions that stratified flows in such segment were achieved. Two radiation detectors located at 80 and 100 m from injection point were used to generate residence time distribution (RTD) curve resulting from injection of radiotracer solutions. Multiphase computational fluid dynamics (CFD) simulations using Eulerian-Eulerian control volume and commercial CFD package Fluent 6.2 were employed to simulate separation length of multiphase flow. The results of study shows that the flow velocity of water is higher than the flow rate of crude oil in water-dominated system despite the higher density of water than the density of the crude oil. The separation length in multiphase flow predicted by Fluent mixture model is approximately 20 m, measured from injection point. This result confirms that the placement of the first radiation detector at the distance 80 m from the injection point was correct. (author)

Prediction of Separation Length of Turbulent Multiphase Flow Using Radiotracer and Computational Fluid Dynamics Simulation

Directory of Open Access Journals (Sweden)

S. Sugiharto1

2013-04-01

Full Text Available Multiphase flow modeling presents great challenges due to its extreme importance in various industrial and environmental applications. In the present study, prediction of separation length of multiphase flow is examined experimentally by injection of two kinds of iodine-based radiotracer solutions into a hydrocarbon transport pipeline (HCT having an inner diameter of 24 in (60,96 m. The main components of fluids in the pipeline are water 95%, crude oil 3% and gas 2%. A radiotracing experiment was carried out at the segment of pipe which is located far from branch points with assumptions that stratified flows in such segment were achieved. Two radiation detectors located at 80 and 100 m from injection point were used to generate residence time distribution (RTD curve resulting from injection of radiotracer solutions. Multiphase computational fluid dynamics (CFD simulations using Eulerian-Eulerian control volume and commercial CFD package Fluent 6.2 were employed to simulate separation length of multiphase flow. The results of study shows that the flow velocity of water is higher than the flow rate of crude oil in water-dominated system despite the higher density of water than the density of the crude oil. The separation length in multiphase flow predicted by Fluent mixture model is approximately 20 m, measured from injection point. This result confirms that the placement of the first radiation detector at the distance 80 m from the injection point was correct

Electrical capacitance tomography (ECT) and gamma radiation meter for comparison with and validation and tuning of computational fluid dynamics (CFD) modeling of multiphase flow

Science.gov (United States)

Pradeep, Chaminda; Yan, Ru; Vestøl, Sondre; Melaaen, Morten C.; Mylvaganam, Saba

2014-07-01

The electrical capacitance tomographic (ECT) approach is increasingly seen as attractive for measurement and control applications in the process industries. Recently, there is increased interest in using the tomographic details from ECT for comparing with and validating and tuning CFD models of multiphase flow. Collaboration with researchers working in the field of computational fluid dynamics (CFD) modeling of multiphase flows gives valuable information for both groups of researchers in the field of ECT and CFD. By studying the ECT tomograms of multiphase flows under carefully monitored inflow conditions of the different media and by obtaining the capacitance values, C(i, j, t) with i = 1…N, j = 1, 2,…N and i ≠ j obtained from ECT modules with N electrodes, it is shown how the interface heights in a pipe with stratified flow of oil and air can be fruitfully compared to the values of those obtained from ECT and gamma radiation meter (GRM) for improving CFD modeling. Monitored inflow conditions in this study are flow rates of air, water and oil into a pipe which can be positioned at varying inclinations to the horizontal, thus emulating the pipelines laid in subsea installations. It is found that ECT-based tomograms show most of the features seen in the GRM-based visualizations with nearly one-to-one correspondence to interface heights obtained from these two methods, albeit some anomalies at the pipe wall. However, there are some interesting features the ECT manages to capture: features which the GRM or the CFD modeling apparently do not show, possibly due to parameters not defined in the inputs to the CFD model or much slower response of the GRM. Results presented in this paper indicate that a combination of ECT and GRM and preferably with other modalities with enhanced data fusion and analysis combined with CFD modeling can help to improve the modeling, measurement and control of multiphase flow in the oil and gas industries and in the process industries

Interface COMSOL-PHREEQC (iCP), an efficient numerical framework for the solution of coupled multiphysics and geochemistry

Science.gov (United States)

Nardi, Albert; Idiart, Andrés; Trinchero, Paolo; de Vries, Luis Manuel; Molinero, Jorge

2014-08-01

This paper presents the development, verification and application of an efficient interface, denoted as iCP, which couples two standalone simulation programs: the general purpose Finite Element framework COMSOL Multiphysics® and the geochemical simulator PHREEQC. The main goal of the interface is to maximize the synergies between the aforementioned codes, providing a numerical platform that can efficiently simulate a wide number of multiphysics problems coupled with geochemistry. iCP is written in Java and uses the IPhreeqc C++ dynamic library and the COMSOL Java-API. Given the large computational requirements of the aforementioned coupled models, special emphasis has been placed on numerical robustness and efficiency. To this end, the geochemical reactions are solved in parallel by balancing the computational load over multiple threads. First, a benchmark exercise is used to test the reliability of iCP regarding flow and reactive transport. Then, a large scale thermo-hydro-chemical (THC) problem is solved to show the code capabilities. The results of the verification exercise are successfully compared with those obtained using PHREEQC and the application case demonstrates the scalability of a large scale model, at least up to 32 threads.

An approach for coupled-code multiphysics core simulations from a common input

International Nuclear Information System (INIS)

Schmidt, Rodney; Belcourt, Kenneth; Hooper, Russell; Pawlowski, Roger; Clarno, Kevin; Simunovic, Srdjan; Slattery, Stuart; Turner, John; Palmtag, Scott

2015-01-01

Highlights: • We describe an approach for coupled-code multiphysics reactor core simulations. • The approach can enable tight coupling of distinct physics codes with a common input. • Multi-code multiphysics coupling and parallel data transfer issues are explained. • The common input approach and how the information is processed is described. • Capabilities are demonstrated on an eigenvalue and power distribution calculation. - Abstract: This paper describes an approach for coupled-code multiphysics reactor core simulations that is being developed by the Virtual Environment for Reactor Applications (VERA) project in the Consortium for Advanced Simulation of Light-Water Reactors (CASL). In this approach a user creates a single problem description, called the “VERAIn” common input file, to define and setup the desired coupled-code reactor core simulation. A preprocessing step accepts the VERAIn file and generates a set of fully consistent input files for the different physics codes being coupled. The problem is then solved using a single-executable coupled-code simulation tool applicable to the problem, which is built using VERA infrastructure software tools and the set of physics codes required for the problem of interest. The approach is demonstrated by performing an eigenvalue and power distribution calculation of a typical three-dimensional 17 × 17 assembly with thermal–hydraulic and fuel temperature feedback. All neutronics aspects of the problem (cross-section calculation, neutron transport, power release) are solved using the Insilico code suite and are fully coupled to a thermal–hydraulic analysis calculated by the Cobra-TF (CTF) code. The single-executable coupled-code (Insilico-CTF) simulation tool is created using several VERA tools, including LIME (Lightweight Integrating Multiphysics Environment for coupling codes), DTK (Data Transfer Kit), Trilinos, and TriBITS. Parallel calculations are performed on the Titan supercomputer at Oak

Load-Flow in Multiphase Distribution Networks: Existence, Uniqueness, Non-Singularity, and Linear Models

Energy Technology Data Exchange (ETDEWEB)

Bernstein, Andrey [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dall-Anese, Emiliano [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zhao, Changhong [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wang, Cong [Ecole Polytechnique Federale de Lausanne (EPFL); Le Boudec, Jean-Yves [Ecole Polytechnique Federale de Lausanne (EPFL)

2018-04-06

This paper considers unbalanced multiphase distribution systems with generic topology and different load models, and extends the Z-bus iterative load-flow algorithm based on a fixed-point interpretation of the AC load-flow equations. Explicit conditions for existence and uniqueness of load-flow solutions are presented. These conditions also guarantee convergence of the load-flow algorithm to the unique solution. The proposed methodology is applicable to generic systems featuring (i) wye connections; (ii) ungrounded delta connections; (iii) a combination of wye-connected and delta-connected sources/loads; and, (iv) a combination of line-to-line and line-to-grounded-neutral devices at the secondary of distribution transformers. Further, a sufficient condition for the non-singularity of the load-flow Jacobian is proposed. Finally, linear load-flow models are derived, and their approximation accuracy is analyzed. Theoretical results are corroborated through experiments on IEEE test feeders.

A QCQP Approach for OPF in Multiphase Radial Networks with Wye and Delta Connections: Preprint

Energy Technology Data Exchange (ETDEWEB)

Zamzam, Ahmed, S.; Zhaoy, Changhong; Dall' Anesey, Emiliano; Sidiropoulos, Nicholas D.

2017-06-27

This paper examines the AC Optimal Power Flow (OPF) problem for multiphase distribution networks featuring renewable energy resources (RESs). We start by outlining a power flow model for radial multiphase systems that accommodates wye-connected and delta-connected RESs and non-controllable energy assets. We then formalize an AC OPF problem that accounts for both types of connections. Similar to various AC OPF renditions, the resultant problem is a non convex quadratically-constrained quadratic program. However, the so-called Feasible Point Pursuit-Successive Convex Approximation algorithm is leveraged to obtain a feasible and yet locally-optimal solution. The merits of the proposed solution approach are demonstrated using two unbalanced multiphase distribution feeders with both wye and delta connections.

Radial Flow in a Multiphase Transport Model at FAIR Energies

Directory of Open Access Journals (Sweden)

Soumya Sarkar

2018-01-01

Full Text Available Azimuthal distributions of radial velocities of charged hadrons produced in nucleus-nucleus (AB collisions are compared with the corresponding azimuthal distribution of charged hadron multiplicity in the framework of a multiphase transport (AMPT model at two different collision energies. The mean radial velocity seems to be a good probe for studying radial expansion. While the anisotropic parts of the distributions indicate a kind of collective nature in the radial expansion of the intermediate “fireball,” their isotropic parts characterize a thermal motion. The present investigation is carried out keeping the upcoming Compressed Baryonic Matter (CBM experiment to be held at the Facility for Antiproton and Ion Research (FAIR in mind. As far as high-energy heavy-ion interactions are concerned, CBM will supplement the Relativistic Heavy-Ion Collider (RHIC and Large Hadron Collider (LHC experiments. In this context our simulation results at high baryochemical potential would be interesting, when scrutinized from the perspective of an almost baryon-free environment achieved at RHIC and LHC.

Seismic wave propagation in heterogeneous multiphasic media: numerical modelling, sensibility and inversion of poro-elastic parameters

International Nuclear Information System (INIS)

Dupuy, B.

2011-11-01

Seismic wave propagation in multiphasic porous media have various environmental (natural risks, geotechnics, groundwater pollutions...) and resources (aquifers, oil and gas, CO 2 storage...) issues. When seismic waves are crossing a given material, they are distorted and thus contain information on fluid and solid phases. This work focuses on the characteristics of seismic waves propagating in multiphasic media, from the physical complex description to the parameter characterisation by inversion, including 2D numerical modelling of the wave propagation. The first part consists in the description of the physics of multiphasic media (each phase and their interactions), using several up-scaling methods, in order to obtain an equivalent mesoscale medium defined by seven parameters. Thus, in simple porosity saturated media and in complex media (double porosity, patchy saturation, visco-poro-elasticity), I can compute seismic wave propagation without any approximation. Indeed, I use a frequency-space domain for the numerical method, which allows to consider all the frequency dependent terms. The spatial discretization employs a discontinuous finite elements method (discontinuous Galerkin), which allows to take into account complex interfaces.The computation of the seismic attributes (velocities and attenuations) of complex porous media shows strong variations in respect with the frequency. Waveforms, computed without approximation, are strongly different if we take into account the full description of the medium or an homogenisation by averages. The last part of this work deals with the poro-elastic parameters characterisation by inversion. For this, I develop a two-steps method: the first one consists in a classical inversion (tomography, full waveform inversion) of seismograms data to obtain macro-scale parameters (seismic attributes). The second step allows to recover, from the macro-scale parameters, the poro-elastic micro-scale properties. This down-scaling step

Using simulation-optimization techniques to improve multiphase aquifer remediation

Energy Technology Data Exchange (ETDEWEB)

Finsterle, S.; Pruess, K. [Lawrence Berkeley Laboratory, Berkeley, CA (United States)

1995-03-01

The T2VOC computer model for simulating the transport of organic chemical contaminants in non-isothermal multiphase systems has been coupled to the ITOUGH2 code which solves parameter optimization problems. This allows one to use linear programming and simulated annealing techniques to solve groundwater management problems, i.e. the optimization of operations for multiphase aquifer remediation. A cost function has to be defined, containing the actual and hypothetical expenses of a cleanup operation which depend - directly or indirectly - on the state variables calculated by T2VOC. Subsequently, the code iteratively determines a remediation strategy (e.g. pumping schedule) which minimizes, for instance, pumping and energy costs, the time for cleanup, and residual contamination. We discuss an illustrative sample problem to discuss potential applications of the code. The study shows that the techniques developed for estimating model parameters can be successfully applied to the solution of remediation management problems. The resulting optimum pumping scheme depends, however, on the formulation of the remediation goals and the relative weighting between individual terms of the cost function.

Seeking simplicity for the understanding of multiphase flows

Science.gov (United States)

Stone, Howard A.

2017-10-01

Fluid mechanics is a discipline with rich phenomena, with motions occurring over an enormous range of length scales, and spanning a wide range of laminar and turbulent flows, instabilities, and applications in industry, nature, biology, and medicine. The subfield of complex fluids typically refers to those flows where the complexity is introduced, for example, by the presence of suspended particles, multiple phases, soft boundaries, and electrokinetic effects; several distinct multiphase flows of Newtonian fluids make up the examples in this article. Interfaces play a significant role and modify the flow with feedback that further changes the shapes of the interfaces. I will provide examples of our work highlighting (i) new features of classical instabilities triggered by changes in geometry, (ii) multiphase flows relevant to the design of liquid-infused substrates exhibiting effective slip while retaining the trapped liquid, and (iii) unexpected dynamics in flow at a T-junction. The interplay of experiments and mathematical models and/or simulations is critical to the new understanding developed.

Multiphase Flow and Fluidization Continuum and Kinetic Theory Descriptions

CERN Document Server

Gidaspow, Dimitri

1994-01-01

Useful as a reference for engineers in industry and as an advanced level text for graduate engineering students, Multiphase Flow and Fluidization takes the reader beyond the theoretical to demonstrate how multiphase flow equations can be used to provide applied, practical, predictive solutions to industrial fluidization problems. Written to help advance progress in the emerging science of multiphase flow, this book begins with the development of the conservation laws and moves on through kinetic theory, clarifying many physical concepts (such as particulate viscosity and solids pressure) and i

The application of a multi-physics tool kit to spatial reactor dynamics

International Nuclear Information System (INIS)

Clifford, I.; Jasak, H.

2009-01-01

Traditionally coupled field nuclear reactor analysis has been carried out using several loosely coupled solvers, each having been developed independently from the others. In the field of multi-physics, the current generation of object-oriented tool kits provides robust close coupling of multiple fields on a single framework. This paper describes the initial results obtained as part of continuing research in the use of the OpenFOAM multi-physics tool kit for reactor dynamics application development. An unstructured, three-dimensional, time-dependent multi-group diffusion code Diffusion FOAM has been developed using the OpenFOAM multi-physics tool kit as a basis. The code is based on the finite-volume methodology and uses a newly developed block-coupled sparse matrix solver for the coupled solution of the multi-group diffusion equations. A description of this code is given with particular emphasis on the newly developed block-coupled solver, along with a selection of results obtained thus far. The code has performed well, indicating that the OpenFOAM tool kit is suited to reactor dynamics applications. This work has shown that the neutronics and simplified thermal-hydraulics of a reactor May be represented and solved for using a common calculation platform, and opens up the possibility for research into robust close-coupling of neutron diffusion and thermal-fluid calculations. This work has further opened up the possibility for research in a number of other areas, including research into three-dimensional unstructured meshes for reactor dynamics applications. (authors)

Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries

Science.gov (United States)

Xu, Ao; Shyy, Wei; Zhao, Tianshou

2017-06-01

Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.

The cell method for electrical engineering and multiphysics problems an introduction

CERN Document Server

Alotto, Piergiorgio; Repetto, Maurizio; Rosso, Carlo

2013-01-01

This book presents a numerical scheme for the solution of field problems governed by partial differential equations: the cell method. The technique lends itself naturally to the solution of multiphysics problems with several interacting phenomena. The Cell Method, based on a space-time tessellation, is intimately related to the work of Tonti and to his ideas of classification diagrams or, as they are nowadays called, Tonti diagrams: a graphical representation of the problem's equations made possible by a suitable selection of a space-time framework relating physical variables to each other. The main features of the cell method are presented and links with many other discrete numerical methods (finite integration techniques, finite difference time domain, finite volumes, mimetic finite differences, etc.) are discussed. After outlining the theoretical basis of the method, a set of physical problems which have been solved with the cell method is described. These single and multiphysics problems stem from the aut...

Investigation on stresses of superconductors under pulsed magnetic fields based on multiphysics model

International Nuclear Information System (INIS)

Yang, Xiaobin; Li, Xiuhong; He, Yafeng; Wang, Xiaojun; Xu, Bo

2017-01-01

Highlights: • The differential equation including temperature and magnetic field was derived for a long cylindrical superconductor. • Thermal stress and electromagnetic stress were studied at the same time under pulse field magnetizing. • The distributions of the magnetic field, the temperature and stresses are studied and compared for two pulse fields of the different duration. • The Role thermal stress and electromagnetic stress play in the process of pulse field magnetizing is discussed. - Abstract: A multiphysics model for the numerical computation of stresses, trapped field and temperature distribution of a infinite long superconducting cylinder is proposed, based on which the stresses, including the thermal stresses and mechanical stresses due to Lorentz force, and trapped fields in the superconductor subjected to pulsed magnetic fields are analyzed. By comparing the results under pulsed magnetic fields with different pulse durations, it is found that the both the mechanical stress due to the electromagnetic force and the thermal stress due to temperature gradient contribute to the total stress level in the superconductor. For pulsed magnetic field with short durations, the thermal stress is the dominant contribution to the total stress, because the heat generated by AC-loss builds up significant temperature gradient in such short durations. However, for a pulsed field with a long duration the gradient of temperature and flux, as well as the maximal tensile stress, are much smaller. And the results of this paper is meaningful for the design and manufacture of superconducting permanent magnets.

Investigation on stresses of superconductors under pulsed magnetic fields based on multiphysics model

Energy Technology Data Exchange (ETDEWEB)

Yang, Xiaobin, E-mail: yangxb@lzu.edu.cn; Li, Xiuhong; He, Yafeng; Wang, Xiaojun; Xu, Bo

2017-04-15

Highlights: • The differential equation including temperature and magnetic field was derived for a long cylindrical superconductor. • Thermal stress and electromagnetic stress were studied at the same time under pulse field magnetizing. • The distributions of the magnetic field, the temperature and stresses are studied and compared for two pulse fields of the different duration. • The Role thermal stress and electromagnetic stress play in the process of pulse field magnetizing is discussed. - Abstract: A multiphysics model for the numerical computation of stresses, trapped field and temperature distribution of a infinite long superconducting cylinder is proposed, based on which the stresses, including the thermal stresses and mechanical stresses due to Lorentz force, and trapped fields in the superconductor subjected to pulsed magnetic fields are analyzed. By comparing the results under pulsed magnetic fields with different pulse durations, it is found that the both the mechanical stress due to the electromagnetic force and the thermal stress due to temperature gradient contribute to the total stress level in the superconductor. For pulsed magnetic field with short durations, the thermal stress is the dominant contribution to the total stress, because the heat generated by AC-loss builds up significant temperature gradient in such short durations. However, for a pulsed field with a long duration the gradient of temperature and flux, as well as the maximal tensile stress, are much smaller. And the results of this paper is meaningful for the design and manufacture of superconducting permanent magnets.

Solidification in Multicomponent Multiphase Systems (SIMMS)

Science.gov (United States)

Rex, S.; Hecht, U.

2005-06-01

The multiphase microstructures that evolve during the solidification of multicomponent alloys are attracting widespread interest for industrial applications and fundamental research.Thermodynamic databases are now well-established for many alloy systems. Thermodynamic calculations provide all the required information about phase equilibria, forming an integral part of both dedicated and comprehensive microstructure models. Among the latter, phase-field modelling has emerged as the method of choice. Solidification experiments are intended to trigger model development or to serve as benchmarks for model validation. For benchmarking, microgravity conditions offer a unique opportunity for avoiding buoyancy-induced convection and buoyancy forces in bulk samples. However, diffusion and the free-energy of interfaces and its anisotropy need to be determined.The measurement of chemical diffusivities in the liquid state can equally benefit from microgravity experiments.

Numerical modelling of multiphase liquid-vapor-gas flows with interfaces and cavitation

Science.gov (United States)

Pelanti, Marica

2017-11-01

We are interested in the simulation of multiphase flows where the dynamical appearance of vapor cavities and evaporation fronts in a liquid is coupled to the dynamics of a third non-condensable gaseous phase. We describe these flows by a single-velocity three-phase compressible flow model composed of the phasic mass and total energy equations, the volume fraction equations, and the mixture momentum equation. The model includes stiff mechanical and thermal relaxation source terms for all the phases, and chemical relaxation terms to describe mass transfer between the liquid and vapor phases of the species that may undergo transition. The flow equations are solved by a mixture-energy-consistent finite volume wave propagation scheme, combined with simple and robust procedures for the treatment of the stiff relaxation terms. An analytical study of the characteristic wave speeds of the hierarchy of relaxed models associated to the parent model system is also presented. We show several numerical experiments, including two-dimensional simulations of underwater explosive phenomena where highly pressurized gases trigger cavitation processes close to a rigid surface or to a free surface. This work was supported by the French Government Grant DGA N. 2012.60.0011.00.470.75.01, and partially by the Norwegian Grant RCN N. 234126/E30.

Computational simulation of biomolecules transport with multi-physics near microchannel surface for development of biomolecules-detection devices.

Science.gov (United States)

Suzuki, Yuma; Shimizu, Tetsuhide; Yang, Ming

2017-01-01

The quantitative evaluation of the biomolecules transport with multi-physics in nano/micro scale is demanded in order to optimize the design of microfluidics device for the biomolecules detection with high detection sensitivity and rapid diagnosis. This paper aimed to investigate the effectivity of the computational simulation using the numerical model of the biomolecules transport with multi-physics near a microchannel surface on the development of biomolecules-detection devices. The biomolecules transport with fluid drag force, electric double layer (EDL) force, and van der Waals force was modeled by Newtonian Equation of motion. The model validity was verified in the influence of ion strength and flow velocity on biomolecules distribution near the surface compared with experimental results of previous studies. The influence of acting forces on its distribution near the surface was investigated by the simulation. The trend of its distribution to ion strength and flow velocity was agreement with the experimental result by the combination of all acting forces. Furthermore, EDL force dominantly influenced its distribution near its surface compared with fluid drag force except for the case of high velocity and low ion strength. The knowledges from the simulation might be useful for the design of biomolecules-detection devices and the simulation can be expected to be applied on its development as the design tool for high detection sensitivity and rapid diagnosis in the future.

A EU simulation platform for nuclear reactor safety: multi-scale and multi-physics calculations, sensitivity and uncertainty analysis (NURESIM project)

International Nuclear Information System (INIS)

Chauliac, Christian; Bestion, Dominique; Crouzet, Nicolas; Aragones, Jose-Maria; Cacuci, Dan Gabriel; Weiss, Frank-Peter; Zimmermann, Martin A.

2010-01-01

The NURESIM project, the numerical simulation platform, is developed in the frame of the NURISP European Collaborative Project (FP7), which includes 22 organizations from 14 European countries. NURESIM intends to be a reference platform providing high quality software tools, physical models, generic functions and assessment results. The NURESIM platform provides an accurate representation of the physical phenomena by promoting and incorporating the latest advances in core physics, two-phase thermal-hydraulics and fuel modelling. It includes multi-scale and multi-physics features, especially for coupling core physics and thermal-hydraulics models for reactor safety. Easy coupling of the different codes and solvers is provided through the use of a common data structure and generic functions (e.g., for interpolation between non-conforming meshes). More generally, the platform includes generic pre-processing, post-processing and supervision functions through the open-source SALOME software, in order to make the codes more user-friendly. The platform also provides the informatics environment for testing and comparing different codes. The contribution summarizes the achievements and ongoing developments of the simulation platform in core physics, thermal-hydraulics, multi-physics, uncertainties and code integration

Non-Linear Multi-Physics Analysis and Multi-Objective Optimization in Electroheating Applications

Czech Academy of Sciences Publication Activity Database

di Barba, P.; Doležel, Ivo; Mognaschi, M. E.; Savini, A.; Karban, P.

2014-01-01

Roč. 50, č. 2 (2014), s. 7016604-7016604 ISSN 0018-9464 Institutional support: RVO:61388998 Keywords : coupled multi-physics problems * finite element method * non-linear equations Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.386, year: 2014

Multi-scale and multi-physics model of the uterine smooth muscle with mechanotransduction.

Science.gov (United States)

Yochum, Maxime; Laforêt, Jérémy; Marque, Catherine

2018-02-01

Preterm labor is an important public health problem. However, the efficiency of the uterine muscle during labor is complex and still poorly understood. This work is a first step towards a model of the uterine muscle, including its electrical and mechanical components, to reach a better understanding of the uterus synchronization. This model is proposed to investigate, by simulation, the possible role of mechanotransduction for the global synchronization of the uterus. The electrical diffusion indeed explains the local propagation of contractile activity, while the tissue stretching may play a role in the synchronization of distant parts of the uterine muscle. This work proposes a multi-physics (electrical, mechanical) and multi-scales (cell, tissue, whole uterus) model, which is applied to a realistic uterus 3D mesh. This model includes electrical components at different scales: generation of action potentials at the cell level, electrical diffusion at the tissue level. It then links these electrical events to the mechanical behavior, at the cellular level (via the intracellular calcium concentration), by simulating the force generated by each active cell. It thus computes an estimation of the intra uterine pressure (IUP) by integrating the forces generated by each active cell at the whole uterine level, as well as the stretching of the tissue (by using a viscoelastic law for the behavior of the tissue). It finally includes at the cellular level stretch activated channels (SACs) that permit to create a loop between the mechanical and the electrical behavior (mechanotransduction). The simulation of different activated regions of the uterus, which in this first "proof of concept" case are electrically isolated, permits the activation of inactive regions through the stretching (induced by the electrically active regions) computed at the whole organ scale. This permits us to evidence the role of the mechanotransduction in the global synchronization of the uterus. The

Uncertainties propagation in the framework of a Rod Ejection Accident modeling based on a multi-physics approach

Energy Technology Data Exchange (ETDEWEB)

Le Pallec, J. C.; Crouzet, N.; Bergeaud, V.; Delavaud, C. [CEA/DEN/DM2S, CEA/Saclay, 91191 Gif sur Yvette Cedex (France)

2012-07-01

The control of uncertainties in the field of reactor physics and their propagation in best-estimate modeling are a major issue in safety analysis. In this framework, the CEA develops a methodology to perform multi-physics simulations including uncertainties analysis. The present paper aims to present and apply this methodology for the analysis of an accidental situation such as REA (Rod Ejection Accident). This accident is characterized by a strong interaction between the different areas of the reactor physics (neutronic, fuel thermal and thermal hydraulic). The modeling is performed with CRONOS2 code. The uncertainties analysis has been conducted with the URANIE platform developed by the CEA: For each identified response from the modeling (output) and considering a set of key parameters with their uncertainties (input), a surrogate model in the form of a neural network has been produced. The set of neural networks is then used to carry out a sensitivity analysis which consists on a global variance analysis with the determination of the Sobol indices for all responses. The sensitivity indices are obtained for the input parameters by an approach based on the use of polynomial chaos. The present exercise helped to develop a methodological flow scheme, to consolidate the use of URANIE tool in the framework of parallel calculations. Finally, the use of polynomial chaos allowed computing high order sensitivity indices and thus highlighting and classifying the influence of identified uncertainties on each response of the analysis (single and interaction effects). (authors)

2nd International Conference on Multiphase Flow - ICMF '95

CERN Document Server

Fukano, T; Bataille, Jean

1995-01-01

There is increasing world-wide interest in obtaining an understanding of various multiphase flow phenomena and problems in terms of a common language of multiphase flow. This volume contains state-of-the-art papers which have been contributed from all over the world by experts working on all aspects of multiphase flows. The volume also highlights international technology-sharing in the fields of energy, environment and public health, in order to create a brighter and sustainable future for man and for all life in the next century. It is intended that this volume will serve as a major source of

High-temperature multiphase flowmeters in heavy-oil thermal production

Energy Technology Data Exchange (ETDEWEB)

Mehdizadeh, P. [Society of Petroleum Engineers, Richardson, TX (United States)]|[Production Technology Inc. (United States)

2005-11-01

A review of field tests assessing the capability and advantages of multi-phase metering technology in high temperature thermal recovery processes such as cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD) was presented. A number of different tank gauging procedures were conducted to obtain a reference flow rate. Subsequent performance tests of metered data and tank data verified the accuracy of the meter, and that water cut sampling can be attained under practical field conditions. A 12 well field test was then conducted, and an allocation factor was obtained from conventional test separators and production measurements. An improvement in the allocation factor was noted. However, a full evaluation of the multiphase meter data obtained in the field was limited by the quality of the reference field data. A 30 day well testing campaign showed a comparison of well rate data from the multi-phase meter with data from an emulsion meter. It was concluded that the multiphase meter provided consistent measurements, matching the level of accuracy attained from rigorous tank measurements. In addition, the multiphase meter eliminated the need for the equipment modifications and extra personnel interventions needed to perform tank testing and manual and automatic water cut sampling. 15 refs., 2 tabs., 6 figs.

Improvement in Sachdeva's multiphase choke flow model using field data

Energy Technology Data Exchange (ETDEWEB)

Guo, B.; Ghalambor, A. [Louisiana Univ. at Lafayette, LA (United States); Al-Bemani, A.S. [Sultan Qaboos Univ., Muscat (Oman)

2002-06-01

To control fluid production rates from wells, to maintain stable pressure downstream from the choke, and to provide the required backpressure to a reservoir to avoid formation damage from excessive drawdown, oil and gas producers use wellhead chokes. The prediction of critical-subcritical boundary and liquid and gas flow rates for multiphase crude systems has been accomplished using the Sachdeva choke flow model. Based on data from 239 oil wells and 273 gas condensate wells in Southwest Louisiana, the authors evaluated the accuracy of the Sachdeva choke model, which had been found lacking in some applications. The authors concluded from a comparison of the results obtained from measurements and model calculations that the accuracy of the model was better in the case of oil wells rather than gas condensate wells. The use of different values of choke discharge coefficient could lead to the minimization of the error of the model. The choke discharge coefficient to be used for oil wells was determined to be 1.08 for liquid rate predictions, and 0.78 for gas rate predictions. In the case of gas condensate wells, a coefficient of 1.07 was recommended for gas prediction rates, while a coefficient of 1.53 was recommended by the authors for liquid rate predictions. 30 refs., 1 tab., 13 figs.

Modeling Manufacturing Impacts on Aging and Reliability of Polyurethane Foams

Energy Technology Data Exchange (ETDEWEB)

Rao, Rekha R.; Roberts, Christine Cardinal; Mondy, Lisa Ann; Soehnel, Melissa Marie; Johnson, Kyle; Lorenzo, Henry T.

2016-10-01

Polyurethane is a complex multiphase material that evolves from a viscous liquid to a system of percolating bubbles, which are created via a CO2 generating reaction. The continuous phase polymerizes to a solid during the foaming process generating heat. Foams introduced into a mold increase their volume up to tenfold, and the dynamics of the expansion process may lead to voids and will produce gradients in density and degree of polymerization. These inhomogeneities can lead to structural stability issues upon aging. For instance, structural components in weapon systems have been shown to change shape as they age depending on their molding history, which can threaten critical tolerances. The purpose of this project is to develop a Cradle-to-Grave multiphysics model, which allows us to predict the material properties of foam from its birth through aging in the stockpile, where its dimensional stability is important.

Computation of multiphase systems with phase field models

International Nuclear Information System (INIS)

Badalassi, V.E.; Ceniceros, H.D.; Banerjee, S.

2003-01-01

Phase field models offer a systematic physical approach for investigating complex multiphase systems behaviors such as near-critical interfacial phenomena, phase separation under shear, and microstructure evolution during solidification. However, because interfaces are replaced by thin transition regions (diffuse interfaces), phase field simulations require resolution of very thin layers to capture the physics of the problems studied. This demands robust numerical methods that can efficiently achieve high resolution and accuracy, especially in three dimensions. We present here an accurate and efficient numerical method to solve the coupled Cahn-Hilliard/Navier-Stokes system, known as Model H, that constitutes a phase field model for density-matched binary fluids with variable mobility and viscosity. The numerical method is a time-split scheme that combines a novel semi-implicit discretization for the convective Cahn-Hilliard equation with an innovative application of high-resolution schemes employed for direct numerical simulations of turbulence. This new semi-implicit discretization is simple but effective since it removes the stability constraint due to the nonlinearity of the Cahn-Hilliard equation at the same cost as that of an explicit scheme. It is derived from a discretization used for diffusive problems that we further enhance to efficiently solve flow problems with variable mobility and viscosity. Moreover, we solve the Navier-Stokes equations with a robust time-discretization of the projection method that guarantees better stability properties than those for Crank-Nicolson-based projection methods. For channel geometries, the method uses a spectral discretization in the streamwise and spanwise directions and a combination of spectral and high order compact finite difference discretizations in the wall normal direction. The capabilities of the method are demonstrated with several examples including phase separation with, and without, shear in two and three

Contribution to the study of multi-physical phenomena in cementitious materials

International Nuclear Information System (INIS)

Bary, B.

2010-09-01

This document is a synthesis of the applied research studies undertaken by the author during ten years, first at the University of Marne-La-Vallee during the period 1999-2002, then at the CEA. These studies concern the modeling and the numerical simulations of the cementitious materials behavior subjected on the one hand to moderate thermomechanical and hydric loadings, and on the other hand to chemical attacks due to the migration of calcium, carbonate and sulfate ions. The developed approaches may be viewed as multi-physical in the sense that the models used for describing the behavior couple various fields and phenomena such as mechanics, thermal, hydric and ionic transfers, and chemistry. In addition, analytical up-scaling techniques are applied to estimate the physical properties associated with these phenomena (mechanical, hydraulic and diffusive parameters) as a function of the microstructure and the hydric state of the material. (author)

A new general methodology for incorporating physico-chemical transformations into multi-phase wastewater treatment process models.

Science.gov (United States)

Lizarralde, I; Fernández-Arévalo, T; Brouckaert, C; Vanrolleghem, P; Ikumi, D S; Ekama, G A; Ayesa, E; Grau, P

2015-05-01

This paper introduces a new general methodology for incorporating physico-chemical and chemical transformations into multi-phase wastewater treatment process models in a systematic and rigorous way under a Plant-Wide modelling (PWM) framework. The methodology presented in this paper requires the selection of the relevant biochemical, chemical and physico-chemical transformations taking place and the definition of the mass transport for the co-existing phases. As an example a mathematical model has been constructed to describe a system for biological COD, nitrogen and phosphorus removal, liquid-gas transfer, precipitation processes, and chemical reactions. The capability of the model has been tested by comparing simulated and experimental results for a nutrient removal system with sludge digestion. Finally, a scenario analysis has been undertaken to show the potential of the obtained mathematical model to study phosphorus recovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Senior Project-Based Multiphase Motor Drive System Development

Science.gov (United States)

Abdel-Khalik, Ayman S.; Massoud, Ahmed M.; Ahmed, Shehab

2016-01-01

Adjustable-speed drives based on multiphase motors are of significant interest for safety-critical applications that necessitate wide fault-tolerant capabilities and high system reliability. Although multiphase machines are based on the same conceptual theory as three-phase machines, most undergraduate electrical machines and electric drives…

Electromagnetic fields in small systems from a multiphase transport model

Science.gov (United States)

Zhao, Xin-Li; Ma, Yu-Gang; Ma, Guo-Liang

2018-02-01

We calculate the electromagnetic fields generated in small systems by using a multiphase transport (AMPT) model. Compared to A +A collisions, we find that the absolute electric and magnetic fields are not small in p +Au and d +Au collisions at energies available at the BNL Relativistic Heavy Ion Collider and in p +Pb collisions at energies available at the CERN Large Hadron Collider. We study the centrality dependencies and the spatial distributions of electromagnetic fields. We further investigate the azimuthal fluctuations of the magnetic field and its correlation with the fluctuating geometry using event-by-event simulations. We find that the azimuthal correlation 〈" close="〉cos(ϕα+ϕβ-2 ΨRP)〉">cos2 (ΨB-Ψ2) between the magnetic field direction and the second-harmonic participant plane is almost zero in small systems with high multiplicities, but not in those with low multiplicities. This indicates that the charge azimuthal correlation is not a valid probe to study the chiral magnetic effect (CME) in small systems with high multiplicities. However, we suggest searching for possible CME effects in small systems with low multiplicities.

Analysis of a bubble coalescence in the multiphase lattice Boltzmann method

International Nuclear Information System (INIS)

Ryu, Seung Yeob; Park, Cheon Tae; Lee, Chung Chan; Kim, Keung Koo

2008-01-01

Recently, the lattice Boltzmann method (LBM) has gained much attention for its ability to simulate fluid flows, and for its potential advantages over a conventional CFD method. The key advantages of LBM are, (1) suitability for parallel computations, (2) absence of the need to solve the time-consuming Poisson equation for a pressure, and (3) an ease with multiphase flows, complex geometries and interfacial dynamics may be treated. To study the effect of the mobility coefficient Γ and the width of the interface layer, two stationary bubbles without a collision are considered. The gap of the two bubbles is taken as 4, while the width of the interface (w) and the mobility coefficient Γ are varied. In the present work, the lattice Boltzmann model for multiphase flows proposed by Zheng et al. is used for simulating two stationary bubbles without a collision. By adopting a finite difference gradient operator of a sufficient isotropy, the spurious currents can be made smaller. The main objective of the present work is to establish the lattice Boltzmann method as a viable tool for the simulation of multiphase or multi-component flows

Fundamentals of Turbulent and Multi-Phase Combustion

CERN Document Server

Kuo, Kenneth Kuan-yun

2012-01-01

Detailed coverage of advanced combustion topics from the author of Principles of Combustion, Second Edition Turbulence, turbulent combustion, and multiphase reacting flows have become major research topics in recent decades due to their application across diverse fields, including energy, environment, propulsion, transportation, industrial safety, and nanotechnology. Most of the knowledge accumulated from this research has never been published in book form-until now. Fundamentals of Turbulent and Multiphase Combustion presents up-to-date, integrated coverage of the fundamentals of turbulence

Module-based Hybrid Uncertainty Quantification for Multi-physics Applications: Theory and Software

Energy Technology Data Exchange (ETDEWEB)

Tong, Charles [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chen, Xiao [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Iaccarino, Gianluca [Stanford Univ., CA (United States); Mittal, Akshay [Stanford Univ., CA (United States)

2013-10-08

In this project we proposed to develop an innovative uncertainty quantification methodology that captures the best of the two competing approaches in UQ, namely, intrusive and non-intrusive approaches. The idea is to develop the mathematics and the associated computational framework and algorithms to facilitate the use of intrusive or non-intrusive UQ methods in different modules of a multi-physics multi-module simulation model in a way that physics code developers for different modules are shielded (as much as possible) from the chores of accounting for the uncertain ties introduced by the other modules. As the result of our research and development, we have produced a number of publications, conference presentations, and a software product.

Multiphase flows in complex geometries: a UQ perspective

KAUST Repository

Icardi, Matteo

2015-01-01

Nowadays computer simulations are widely used in many multiphase flow applications involving interphases, dispersed particles, and complex geometries. Most of these problems are solved with mixed models composed of fundamental physical laws, rigorous mathematical upscaling, and empirical correlations/closures. This means that classical inference techniques or forward parametric studies, for example, becomes computationally prohibitive and must take into account the physical meaning and constraints of the equations. However mathematical techniques commonly used in Uncertainty Quantification can come to the aid for the (i) modeling, (ii) simulation, and (iii) validation steps. Two relevant applications for environmental, petroleum, and chemical engineering will be presented to highlight these aspects and the importance of bridging the gaps between engineering applications, computational physics and mathematical methods. The first example is related to the mathematical modeling of sub-grid/sub-scale information with Probability Density Function (PDF) models in problems involving flow, mixing, and reaction in random environment. After a short overview of the research field, some connections and similarities with Polynomial Chaos techniques, will be investigated. In the second example, averaged correlations laws and effective parameters for multiphase flow and their statistical fluctuations, will be considered and efficient computational techniques, borrowed from high-dimensional stochastic PDE problems, will be applied. In presence of interfacial flow, where small spatial scales and fast time scales are neglected, the assessment of robustness and predictive capabilities are studied. These illustrative examples are inspired by common problems arising, for example, from the modeling and simulation of turbulent and porous media flows.

Multiphase flows in complex geometries: a UQ perspective

KAUST Repository

Icardi, Matteo

2015-01-07

Nowadays computer simulations are widely used in many multiphase flow applications involving interphases, dispersed particles, and complex geometries. Most of these problems are solved with mixed models composed of fundamental physical laws, rigorous mathematical upscaling, and empirical correlations/closures. This means that classical inference techniques or forward parametric studies, for example, becomes computationally prohibitive and must take into account the physical meaning and constraints of the equations. However mathematical techniques commonly used in Uncertainty Quantification can come to the aid for the (i) modeling, (ii) simulation, and (iii) validation steps. Two relevant applications for environmental, petroleum, and chemical engineering will be presented to highlight these aspects and the importance of bridging the gaps between engineering applications, computational physics and mathematical methods. The first example is related to the mathematical modeling of sub-grid/sub-scale information with Probability Density Function (PDF) models in problems involving flow, mixing, and reaction in random environment. After a short overview of the research field, some connections and similarities with Polynomial Chaos techniques, will be investigated. In the second example, averaged correlations laws and effective parameters for multiphase flow and their statistical fluctuations, will be considered and efficient computational techniques, borrowed from high-dimensional stochastic PDE problems, will be applied. In presence of interfacial flow, where small spatial scales and fast time scales are neglected, the assessment of robustness and predictive capabilities are studied. These illustrative examples are inspired by common problems arising, for example, from the modeling and simulation of turbulent and porous media flows.

The Henry-Saltwater Intrusion Benchmark – Alternatives in Multiphysics Formulations and Solution Strategies

Directory of Open Access Journals (Sweden)

E Holzbecher

2016-03-01

Full Text Available In a classical paper Henry set up a conceptual model for simulating saltwater intrusion into coastal aquifers. Up to now the problem has been taken up by software developers and modellers as a benchmark for codes simulating coupled flow and transport in porous media. The Henry test case has been treated using different numerical methods based on various formulations of differential equations. We compare several of these approaches using multiphysics software. We model the problem using Finite Elements, utilizing the primitive variables and the streamfunction approach, both with and without using the Oberbeck-Boussinesq assumption. We compare directly coupled solvers with segregated solver strategies. Changing finite element orders and mesh refinement, we find that models based on the streamfunction converge 2-4 times faster than runs based on primitive variables. Concerning the solution strategy, we find an advantage of Picard iterations compared to monolithic Newton iterations.

Multiphase anodic layers and prospects of their application

International Nuclear Information System (INIS)

Rudnev, V.S.

2008-01-01

Data on the phase composition of multiphase layers prepared on valve metals (aluminium, titanium, and their alloys) by the plasma-electrochemical oxidation and deposition (PEOD) from aqueous electrolytes containing iso- and heteropolyoxoanions, polyphosphate and fluoride metal complexes (M=Eu, Y, Hf, Nb, Zr, W), as well as electrolytes evolving solid precipitates, is summarized. Possible application fields of the metal/multiphase PEOD surface structure compositions are considered [ru

Multiphase modelling of vascular tumour growth in two spatial dimensions

KAUST Repository

Hubbard, M.E.

2013-01-01

In this paper we present a continuum mathematical model of vascular tumour growth which is based on a multiphase framework in which the tissue is decomposed into four distinct phases and the principles of conservation of mass and momentum are applied to the normal/healthy cells, tumour cells, blood vessels and extracellular material. The inclusion of a diffusible nutrient, supplied by the blood vessels, allows the vasculature to have a nonlocal influence on the other phases. Two-dimensional computational simulations are carried out on unstructured, triangular meshes to allow a natural treatment of irregular geometries, and the tumour boundary is captured as a diffuse interface on this mesh, thereby obviating the need to explicitly track the (potentially highly irregular and ill-defined) tumour boundary. A hybrid finite volume/finite element algorithm is used to discretise the continuum model: the application of a conservative, upwind, finite volume scheme to the hyperbolic mass balance equations and a finite element scheme with a stable element pair to the generalised Stokes equations derived from momentum balance, leads to a robust algorithm which does not use any form of artificial stabilisation. The use of a matrix-free Newton iteration with a finite element scheme for the nutrient reaction-diffusion equations allows full nonlinearity in the source terms of the mathematical model.Numerical simulations reveal that this four-phase model reproduces the characteristic pattern of tumour growth in which a necrotic core forms behind an expanding rim of well-vascularised proliferating tumour cells. The simulations consistently predict linear tumour growth rates. The dependence of both the speed with which the tumour grows and the irregularity of the invading tumour front on the model parameters is investigated. © 2012 Elsevier Ltd.

Prediction of critical transport velocity for preventing sand deposition in gas-oil multiphase production and well systems

Energy Technology Data Exchange (ETDEWEB)

Bello, O.O.; Reinicke, K.M. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. of Petroleum Engineering; Teodoriu, C. [Texas A and M Univ., College Station, TX (United States). Dept. of Petroleum Engineering

2008-10-23

The critical transport velocity is one of the key parameters for gas-oil-sand multiphase production and well system design and safe operation. Existing American Petroleum Institute Recommended Practice 14E (API RP 14E) for the sizing of multiphase flow systems suggests an equation to calculate threshold transport velocity. This equation only considers mixture density and does not account for factors such as fluid properties, gas-liquid flow patterns, sand loading, sand particle size, size distributions, shape factor and density. This work presents an improved computational methodology, which can be applied to estimate the critical transport velocity required to ensure efficient performance of gas-oil-sand multiphase production and well systems. The improved method is based on the modelling of three-phase gas-oil-sand pipe flow physics from first principle. Computations of the critical transport velocities show reasonable agreement with values calculated from mechanistic model (Danielson, 2007) for a relatively wide range of design and operating conditions. Compared with the mechanistic model (Danielson, 2007), the present method has no imposed limitations to the range of applicability. It is also takes into adequate account the effects of operating pressure, flow geometry, sand particle size, size distribution and shape factor, which have considerable influence on the critical transport velocity in gas-oil-sand multiphase production and well systems. (orig.)

Hysteresis in multiphase microfluidics at a T-junction.

Science.gov (United States)

Zagnoni, Michele; Anderson, Jamie; Cooper, Jonathan M

2010-06-15

Multiphase microfluidics offer a wide range of functionalities in the fields of fluid dynamics, biology, particle synthesis, and, more recently, also in logical computation. In this article, we describe the hysteresis of immiscible, multiphase flow obtained in hydrophilic, microfluidic systems at a T-junction. Stable and unstable state behaviors, in the form of segmented and parallel flow patterns of oil and water, were reliably produced, depending upon the history of the flow rates applied to the phases. The transition mechanisms between the two states were analyzed both experimentally and using numerical simulations, describing how the physical and fluid dynamic parameters influenced the hysteretic behavior of the flow. The characteristics of these multiphase systems render them suitable to be used as pressure comparators and also for the implementation of microfluidic logic operations.

The Pore-scale modeling of multiphase flows in reservoir rocks using the lattice Boltzmann method

Science.gov (United States)

Mu, Y.; Baldwin, C. H.; Toelke, J.; Grader, A.

2011-12-01

Digital rock physics (DRP) is a new technology to compute the physical and fluid flow properties of reservoir rocks. In this approach, pore scale images of the porous rock are obtained and processed to create highly accurate 3D digital rock sample, and then the rock properties are evaluated by advanced numerical methods at the pore scale. Ingrain's DRP technology is a breakthrough for oil and gas companies that need large volumes of accurate results faster than the current special core analysis (SCAL) laboratories can normally deliver. In this work, we compute the multiphase fluid flow properties of 3D digital rocks using D3Q19 immiscible LBM with two relaxation times (TRT). For efficient implementation on GPU, we improved and reformulated color-gradient model proposed by Gunstensen and Rothmann. Furthermore, we only use one-lattice with the sparse data structure: only allocate memory for pore nodes on GPU. We achieved more than 100 million fluid lattice updates per second (MFLUPS) for two-phase LBM on single Fermi-GPU and high parallel efficiency on Multi-GPUs. We present and discuss our simulation results of important two-phase fluid flow properties, such as capillary pressure and relative permeabilities. We also investigate the effects of resolution and wettability on multiphase flows. Comparison of direct measurement results with the LBM-based simulations shows practical ability of DRP to predict two-phase flow properties of reservoir rock.

MODELING COUPLED PROCESSES OF MULTIPHASE FLOW AND HEAT TRANSFER IN UNSATURATED FRACTURED ROCK

International Nuclear Information System (INIS)

Y. Wu; S. Mukhopadhyay; K. Zhang; G.S. Bodvarsson

2006-01-01

A mountain-scale, thermal-hydrologic (TH) numerical model is developed for investigating unsaturated flow behavior in response to decay heat from the radioactive waste repository at Yucca Mountain, Nevada, USA. The TH model, consisting of three-dimensional (3-D) representations of the unsaturated zone, is based on the current repository design, drift layout, and thermal loading scenario under estimated current and future climate conditions. More specifically, the TH model implements the current geological framework and hydrogeological conceptual models, and incorporates the most updated, best-estimated input parameters. This mountain-scale TH model simulates the coupled TH processes related to mountain-scale multiphase fluid flow, and evaluates the impact of radioactive waste heat on the hydrogeological system, including thermally perturbed liquid saturation, gas- and liquid-phase fluxes, and water and rock temperature elevations, as well as the changes in water flux driven by evaporation/condensation processes and drainage between drifts. For a better description of the ambient geothermal condition of the unsaturated zone system, the TH model is first calibrated against measured borehole temperature data. The ambient temperature calibration provides the necessary surface and water table boundary as well as initial conditions. Then, the TH model is used to obtain scientific understanding of TH processes in the Yucca Mountain unsaturated zone under the designed schedule of repository thermal load

A Multiphase Flow in the Antroduodenal Portion of the Gastrointestinal Tract: A Mathematical Model

Directory of Open Access Journals (Sweden)

P. V. Trusov

2016-01-01

Full Text Available A group of authors has developed a multilevel mathematical model that focuses on functional disorders in a human body associated with various chemical, physical, social, and other factors. At this point, the researchers have come up with structure, basic definitions and concepts of a mathematical model at the “macrolevel” that allow describing processes in a human body as a whole. Currently we are working at the “mesolevel” of organs and systems. Due to complexity of the tasks, this paper deals with only one meso-fragment of a digestive system model. It describes some aspects related to modeling multiphase flow in the antroduodenal portion of the gastrointestinal tract. Biochemical reactions, dissolution of food particles, and motor, secretory, and absorbing functions of the tract are taken into consideration. The paper outlines some results concerning influence of secretory function disorders on food dissolution rate and tract contents acidity. The effect which food density has on inflow of food masses from a stomach to a bowel is analyzed. We assume that the future development of the model will include digestive enzymes and related reactions of lipolysis, proteolysis, and carbohydrates breakdown.

New systematic methodology for incorporating dynamic heat transfer modelling in multi-phase biochemical reactors.

Science.gov (United States)

Fernández-Arévalo, T; Lizarralde, I; Grau, P; Ayesa, E

2014-09-01

This paper presents a new modelling methodology for dynamically predicting the heat produced or consumed in the transformations of any biological reactor using Hess's law. Starting from a complete description of model components stoichiometry and formation enthalpies, the proposed modelling methodology has integrated successfully the simultaneous calculation of both the conventional mass balances and the enthalpy change of reaction in an expandable multi-phase matrix structure, which facilitates a detailed prediction of the main heat fluxes in the biochemical reactors. The methodology has been implemented in a plant-wide modelling methodology in order to facilitate the dynamic description of mass and heat throughout the plant. After validation with literature data, as illustrative examples of the capability of the methodology, two case studies have been described. In the first one, a predenitrification-nitrification dynamic process has been analysed, with the aim of demonstrating the easy integration of the methodology in any system. In the second case study, the simulation of a thermal model for an ATAD has shown the potential of the proposed methodology for analysing the effect of ventilation and influent characterization. Copyright © 2014 Elsevier Ltd. All rights reserved.

Convex Relaxation of OPF in Multiphase Radial Networks with Wye and Delta Connections

Energy Technology Data Exchange (ETDEWEB)

Zhao, Changhong [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dall-Anese, Emiliano [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Low, Steven [California Institute of Technology

2017-08-01

This panel presentation focuses on multiphase radial distribution networks with wye and delta connections, and proposes a semidefinite relaxation of the AC optimal power flow (OPF) problem. Two multiphase power flow models are developed to facilitate the integration of delta-connected loads or generation resources in the OPF problem. The first model is referred to as the extended branch flow model (EBFM). The second model leverages a linear relationship between phase-to-ground power injections and delta connections that holds under a balanced voltage approximation (BVA). Based on these models, pertinent OPF problems are formulated and relaxed to semidefinite programs (SDPs). Numerical studies on IEEE test feeders show that the proposed SDP relaxations can be solved efficiently by a generic optimization solver. Numerical evidence also indicates that solving the resultant SDP under BVA is faster than under EBFM. Moreover, both SDP solutions are numerically exact with respect to voltages and branch flows. It is further shown that the SDP solution under BVA has a small optimality gap, and the BVA model is accurate in the sense that it reproduces actual system voltages.

Final Project Report CFA-14-6357: A New Paradigm for Understanding Multiphase Ceramic Waste Form Performance

Energy Technology Data Exchange (ETDEWEB)

Brinkman, Kyle [Clemson Univ., SC (United States); Bordia, Rajendra [Clemson Univ., SC (United States); Reifsnider, Kenneth [Univ. of South Carolina, Columbia, SC (United States); Chiu, Wilson [Univ. of Connecticut, Storrs, CT (United States); Amoroso, Jake [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-12-28

This project fabricated model multiphase ceramic waste forms with processing-controlled microstructures followed by advanced characterization with synchrotron and electron microscopy-based 3D tomography to provide elemental and chemical state-specific information resulting in compositional phase maps of ceramic composites. Details of 3D microstructural features were incorporated into computer-based simulations using durability data for individual constituent phases as inputs in order to predict the performance of multiphase waste forms with varying microstructure and phase connectivity.

Pore scale study of multiphase multicomponent reactive transport during CO2 dissolution trapping

Science.gov (United States)

Chen, Li; Wang, Mengyi; Kang, Qinjun; Tao, Wenquan

2018-06-01

Solubility trapping is crucial for permanent CO2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO2-water two-phase flow, multicomponent (CO2(aq), H+, HCO3-, CO32- and OH-) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO2(aq) concentration, scCO2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is required by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Finally, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.

Numerical simulation of single-phase and multiphase non-Darcy flowin porous and fractured reservoirs

Energy Technology Data Exchange (ETDEWEB)

Wu, Yu-Shu

2000-06-02

A numerical method as well as a theoretical study of non-Darcy fluid flow of through porous and fractured reservoirs is described. The non-Darcy flow is handled in a three-dimensional, multiphase flow reservoir simulator, while the model formulation incorporates the Forchheimer equation for describing single-phase or multiphase non-Darcy flow and displacement. The numerical scheme has been verified by comparing its results against those of analytical methods. Numerical solutions are used to obtain some insight into the physics of non-Darcy flow and displacement in reservoirs. In addition, several type curves are provided for well-test analyses of non-Darcy flow to demonstrate a methodology for modeling this type of flow in porous and fractured rocks, including flow in geothermal reservoirs.

Multi-phase model development to assess RCIC system capabilities under severe accident conditions

Energy Technology Data Exchange (ETDEWEB)

Kirkland, Karen Vierow [Texas A & M Univ., College Station, TX (United States); Ross, Kyle [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Beeny, Bradley [Texas A & M Univ., College Station, TX (United States); Luthman, Nicholas [Texas A& M Engineering Experiment Station, College Station, TX (United States); Strater, Zachary [Texas A & M Univ., College Station, TX (United States)

2017-12-23

The Reactor Core Isolation Cooling (RCIC) System is a safety-related system that provides makeup water for core cooling of some Boiling Water Reactors (BWRs) with a Mark I containment. The RCIC System consists of a steam-driven Terry turbine that powers a centrifugal, multi-stage pump for providing water to the reactor pressure vessel. The Fukushima Dai-ichi accidents demonstrated that the RCIC System can play an important role under accident conditions in removing core decay heat. The unexpectedly sustained, good performance of the RCIC System in the Fukushima reactor demonstrates, firstly, that its capabilities are not well understood, and secondly, that the system has high potential for extended core cooling in accident scenarios. Better understanding and analysis tools would allow for more options to cope with a severe accident situation and to reduce the consequences. The objectives of this project were to develop physics-based models of the RCIC System, incorporate them into a multi-phase code and validate the models. This Final Technical Report details the progress throughout the project duration and the accomplishments.

A Transformerless Medium Voltage Multiphase Motor Drive System

Directory of Open Access Journals (Sweden)

Dan Wang

2016-04-01

Full Text Available A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP, a complete improved Phase Disposition Pulse Width Modulation (PD-PWM method is developed to ensure the individual DC-link capacitor voltage balancing for enhancing the controllability and limiting the voltage and power stress on the H-bridge cells. A downscaled prototype is designed and developed based on a nine-phase motor. The experimental results verify the excellent performances of the proposed drive system and control strategy in steady-state and variant-frequency startup operations.

Downhole multiphase metering in wells by means of soft-sensing

NARCIS (Netherlands)

Leskens, M.; Kruif, B. de; Belfroid, S.P.C.; Smeulers, J.P.M.; Gryzlov, A.

2008-01-01

Multiphase flow meters are indispensable tools for achieving optimal operation and control of wells as these meters deliver real-time information about their performance. For example, multiphase flow meters located downhole can improve the production of multilateral and multizone wells by timely

Development of axisymmetric lattice Boltzmann flux solver for complex multiphase flows

Science.gov (United States)

Wang, Yan; Shu, Chang; Yang, Li-Ming; Yuan, Hai-Zhuan

2018-05-01

This paper presents an axisymmetric lattice Boltzmann flux solver (LBFS) for simulating axisymmetric multiphase flows. In the solver, the two-dimensional (2D) multiphase LBFS is applied to reconstruct macroscopic fluxes excluding axisymmetric effects. Source terms accounting for axisymmetric effects are introduced directly into the governing equations. As compared to conventional axisymmetric multiphase lattice Boltzmann (LB) method, the present solver has the kinetic feature for flux evaluation and avoids complex derivations of external forcing terms. In addition, the present solver also saves considerable computational efforts in comparison with three-dimensional (3D) computations. The capability of the proposed solver in simulating complex multiphase flows is demonstrated by studying single bubble rising in a circular tube. The obtained results compare well with the published data.

Finite-deformation phase-field chemomechanics for multiphase, multicomponent solids

Science.gov (United States)

Svendsen, Bob; Shanthraj, Pratheek; Raabe, Dierk

2018-03-01

The purpose of this work is the development of a framework for the formulation of geometrically non-linear inelastic chemomechanical models for a mixture of multiple chemical components diffusing among multiple transforming solid phases. The focus here is on general model formulation. No specific model or application is pursued in this work. To this end, basic balance and constitutive relations from non-equilibrium thermodynamics and continuum mixture theory are combined with a phase-field-based description of multicomponent solid phases and their interfaces. Solid phase modeling is based in particular on a chemomechanical free energy and stress relaxation via the evolution of phase-specific concentration fields, order-parameter fields (e.g., related to chemical ordering, structural ordering, or defects), and local internal variables. At the mixture level, differences or contrasts in phase composition and phase local deformation in phase interface regions are treated as mixture internal variables. In this context, various phase interface models are considered. In the equilibrium limit, phase contrasts in composition and local deformation in the phase interface region are determined via bulk energy minimization. On the chemical side, the equilibrium limit of the current model formulation reduces to a multicomponent, multiphase, generalization of existing two-phase binary alloy interface equilibrium conditions (e.g., KKS). On the mechanical side, the equilibrium limit of one interface model considered represents a multiphase generalization of Reuss-Sachs conditions from mechanical homogenization theory. Analogously, other interface models considered represent generalizations of interface equilibrium conditions consistent with laminate and sharp-interface theory. In the last part of the work, selected existing models are formulated within the current framework as special cases and discussed in detail.

Bayesian estimation of magma supply, storage, and eruption rates using a multiphysical volcano model: Kīlauea Volcano, 2000-2012

Science.gov (United States)

Anderson, Kyle R.; Poland, Michael P.

2016-08-01

Estimating rates of magma supply to the world's volcanoes remains one of the most fundamental aims of volcanology. Yet, supply rates can be difficult to estimate even at well-monitored volcanoes, in part because observations are noisy and are usually considered independently rather than as part of a holistic system. In this work we demonstrate a technique for probabilistically estimating time-variable rates of magma supply to a volcano through probabilistic constraint on storage and eruption rates. This approach utilizes Bayesian joint inversion of diverse datasets using predictions from a multiphysical volcano model, and independent prior information derived from previous geophysical, geochemical, and geological studies. The solution to the inverse problem takes the form of a probability density function which takes into account uncertainties in observations and prior information, and which we sample using a Markov chain Monte Carlo algorithm. Applying the technique to Kīlauea Volcano, we develop a model which relates magma flow rates with deformation of the volcano's surface, sulfur dioxide emission rates, lava flow field volumes, and composition of the volcano's basaltic magma. This model accounts for effects and processes mostly neglected in previous supply rate estimates at Kīlauea, including magma compressibility, loss of sulfur to the hydrothermal system, and potential magma storage in the volcano's deep rift zones. We jointly invert data and prior information to estimate rates of supply, storage, and eruption during three recent quasi-steady-state periods at the volcano. Results shed new light on the time-variability of magma supply to Kīlauea, which we find to have increased by 35-100% between 2001 and 2006 (from 0.11-0.17 to 0.18-0.28 km3/yr), before subsequently decreasing to 0.08-0.12 km3/yr by 2012. Changes in supply rate directly impact hazard at the volcano, and were largely responsible for an increase in eruption rate of 60-150% between 2001 and

Multi-phase AC/AC step-down converter for distribution systems

Science.gov (United States)

Aeloiza, Eddy C.; Burgos, Rolando P.

2017-10-25

A step-down AC/AC converter for use in an electric distribution system includes at least one chopper circuit for each one of a plurality of phases of the AC power, each chopper circuit including a four-quadrant switch coupled in series between primary and secondary sides of the chopper circuit and a current-bidirectional two-quadrant switch coupled between the secondary side of the chopper circuit and a common node. Each current-bidirectional two-quadrant switch is oriented in the same direction, with respect to the secondary side of the corresponding chopper circuit and the common node. The converter further includes a control circuit configured to pulse-width-modulate control inputs of the switches, to convert a first multiphase AC voltage at the primary sides of the chopper circuits to a second multiphase AC voltage at the secondary sides of the chopper circuits, the second multiphase AC voltage being lower in voltage than the first multiphase AC voltage.

Electrification of particulates in industrial and natural multiphase flows

CERN Document Server

Gu, Zhaolin

2017-01-01

This book introduces comprehensive fundamentals, numerical simulations and experimental methods of electrification of particulates entrained multiphase flows. The electrifications of two particulate forms, liquid droplets and solid particles, are firstly described together. Liquid droplets can be charged under preset or associated electric fields, while solid particles can be charged through contact. Different charging ways in gas (liquid)-liquid or gas-solid multiphase flows are summarized, including ones that are beneficial to industrial processes, such as electrostatic precipitation, electrostatic spraying, and electrostatic separation, etc., ones harmful for shipping and powder industry, and ones occurring in natural phenomenon, such as wind-blown sand and thunderstorm. This book offers theoretical references to the control and utilization of the charging or charged particulates in multiphase flows as well.

Multi-Phase Modular Drive System: A Case Study in Electrical Aircraft Applications

Directory of Open Access Journals (Sweden)

Charles Onambele

2017-12-01

Full Text Available In this article, an advanced multiphase modular power drive prototype is developed for More Electric Aircraft (MEA. The proposed drive is designed to supply a multi-phase permanent magnet (PM motor rating 120 kW with 24 slots and 11 pole pairs. The power converter of the drive system is based on Silicon Carbide Metal Oxide Semiconductor Field-Effect Transistor (SiC MOSFET technology to operate at high voltage, high frequency and low reverse recovery current. Firstly, an experimental characterization test is performed for the selected SiC power module in harsh conditions to evaluate the switching energy losses. Secondly, a finite element thermal analysis based on Ansys-Icepak is accomplished to validate the selected cooling system for the power converter. Thirdly, a co-simulation model is developed using Matlab-Simulink and LTspice® to evaluate the SiC power module impact on the performance of a multiphase drive system at different operating conditions. The results obtained show that the dynamic performance and efficiency of the power drive are significantly improved, which makes the proposed system an excellent candidate for future aircraft applications.

Multiphase flow and phase change in microgravity: Fundamental research and strategic research for exploration of space

Science.gov (United States)

Singh, Bhim S.

2003-01-01

NASA is preparing to undertake science-driven exploration missions. The NASA Exploration Team's vision is a cascade of stepping stones. The stepping-stone will build the technical capabilities needed for each step with multi-use technologies and capabilities. An Agency-wide technology investment and development program is necessary to implement the vision. The NASA Exploration Team has identified a number of areas where significant advances are needed to overcome all engineering and medical barriers to the expansion of human space exploration beyond low-Earth orbit. Closed-loop life support systems and advanced propulsion and power technologies are among the areas requiring significant advances from the current state-of-the-art. Studies conducted by the National Academy of Science's National Research Council and Workshops organized by NASA have shown that multiphase flow and phase change play a crucial role in many of these advanced technology concepts. Lack of understanding of multiphase flow, phase change, and interfacial phenomena in the microgravity environment has been a major hurdle. An understanding of multiphase flow and phase change in microgravity is, therefore, critical to advancing many technologies needed. Recognizing this, the Office of Biological and Physical Research (OBPR) has initiated a strategic research thrust to augment the ongoing fundamental research in fluid physics and transport phenomena discipline with research especially aimed at understanding key multiphase flow related issues in propulsion, power, thermal control, and closed-loop advanced life support systems. A plan for integrated theoretical and experimental research that has the highest probability of providing data, predictive tools, and models needed by the systems developers to incorporate highly promising multiphase-based technologies is currently in preparation. This plan is being developed with inputs from scientific community, NASA mission planners and industry personnel

Viscosity and surface tension effects during multiphase flow in propped fractures

Science.gov (United States)

Dzikowski, Michał; Dąbrowski, Marcin

2017-04-01

Geological sequestration of CO2 was proposed as an important mechanism to reduce its emission into atmosphere. CO2 exhibits a higher affinity to organic matter than methane molecules and, potentially, it could be pumped and stored in shale reservoirs while enhancing late stage shale gas production. A successful analysis of CO2 sequestration in low matrix permeability rocks such as shales requires a thorough understanding of multiphase flow in stimulated rock fractures, which provide most significant pathways for fluids in such systems. Multiphase fracture flows are also of great relevance to brine, oil and gas migration in petroleum systems, water and stream circulation in geothermal reservoirs, and chemical transport of non-aqueous phase liquids in shallow hydrogeological systems, particularly in partially saturated zones. There are various physical models that describe phenomena taking place during multiphase flow through porous media. One of key aspects that need to be considered are pore-scale effects related to capillarity. Unfortunately, detailed models that describe motion and evolution of phase or component boundary require direct numerical simulations and spatial resolutions that are hard to reach when considering industrial relevant systems. Main aim of the presented work was the development of reduced 2.5D models based on Brinkman approximation of thin domain flow that would be able to capture local scale phenomena without expensive 3D simulations. Presented approach was designed specifically to tackle incompressible and immiscible systems and is based on Continuous Surface Force approach presented by Brackbill et al., implemented using Lattice Boltzmann Method. Presented approach where firstly validated against standard test cases with known classical solution and known experimental data. In the second part, we present and discuss two component, immiscible permeability data for rough and propped fracture obtained with our code for a rage of proppants

Viscous and gravitational fingering in multiphase compositional and compressible flow

Science.gov (United States)

Moortgat, Joachim

2016-03-01

Viscous and gravitational fingering refer to flow instabilities in porous media that are triggered by adverse mobility or density ratios, respectively. These instabilities have been studied extensively in the past for (1) single-phase flow (e.g., contaminant transport in groundwater, first-contact-miscible displacement of oil by gas in hydrocarbon production), and (2) multi-phase immiscible and incompressible flow (e.g., water-alternating-gas (WAG) injection in oil reservoirs). Fingering in multiphase compositional and compressible flow has received much less attention, perhaps due to its high computational complexity. However, many important subsurface processes involve multiple phases that exchange species. Examples are carbon sequestration in saline aquifers and enhanced oil recovery (EOR) by gas or WAG injection below the minimum miscibility pressure. In multiphase flow, relative permeabilities affect the mobility contrast for a given viscosity ratio. Phase behavior can also change local fluid properties, which can either enhance or mitigate viscous and gravitational instabilities. This work presents a detailed study of fingering behavior in compositional multiphase flow in two and three dimensions and considers the effects of (1) Fickian diffusion, (2) mechanical dispersion, (3) flow rates, (4) domain size and geometry, (5) formation heterogeneities, (6) gravity, and (7) relative permeabilities. Results show that fingering in compositional multiphase flow is profoundly different from miscible conditions and upscaling techniques used for the latter case are unlikely to be generalizable to the former.

Contribution of the study of thermal interaction: modelling of a thermal blast in a multi-phase medium

International Nuclear Information System (INIS)

Scott, Edouard

1978-01-01

This research thesis aims at being a contribution to the safety of nuclear facilities by reporting the study of the interaction between nuclear fuel and coolant in simplified conditions. It focuses on the thermal aspect of this interaction between a very hot body and an easily vaporized cold body, which could produce a blast. Thus, this author addresses the field of existence of a thermal blast, and reports the development of a hydrodynamic model which takes the heterogeneous nature of the interacting medium into account, in order to precisely describe the conditions of fuel fragmentation. This model includes the propagation of a shock in a mixture, and the calculation of a multi-phase flow in the reaction zone, and proposes criteria for a self-sustained shock wave propagation in the reactive medium. Results are compared with those obtained with the Bankoff model [fr

Multiphase Interface Tracking with Fast Semi-Lagrangian Contouring.

Science.gov (United States)

Li, Xiaosheng; He, Xiaowei; Liu, Xuehui; Zhang, Jian J; Liu, Baoquan; Wu, Enhua

2016-08-01

We propose a semi-Lagrangian method for multiphase interface tracking. In contrast to previous methods, our method maintains an explicit polygonal mesh, which is reconstructed from an unsigned distance function and an indicator function, to track the interface of arbitrary number of phases. The surface mesh is reconstructed at each step using an efficient multiphase polygonization procedure with precomputed stencils while the distance and indicator function are updated with an accurate semi-Lagrangian path tracing from the meshes of the last step. Furthermore, we provide an adaptive data structure, multiphase distance tree, to accelerate the updating of both the distance function and the indicator function. In addition, the adaptive structure also enables us to contour the distance tree accurately with simple bisection techniques. The major advantage of our method is that it can easily handle topological changes without ambiguities and preserve both the sharp features and the volume well. We will evaluate its efficiency, accuracy and robustness in the results part with several examples.

The Integrated Plasma Simulator: A Flexible Python Framework for Coupled Multiphysics Simulation

Energy Technology Data Exchange (ETDEWEB)

Foley, Samantha S [ORNL; Elwasif, Wael R [ORNL; Bernholdt, David E [ORNL

2011-11-01

High-fidelity coupled multiphysics simulations are an increasingly important aspect of computational science. In many domains, however, there has been very limited experience with simulations of this sort, therefore research in coupled multiphysics often requires computational frameworks with significant flexibility to respond to the changing directions of the physics and mathematics. This paper presents the Integrated Plasma Simulator (IPS), a framework designed for loosely coupled simulations of fusion plasmas. The IPS provides users with a simple component architecture into which a wide range of existing plasma physics codes can be inserted as components. Simulations can take advantage of multiple levels of parallelism supported in the IPS, and can be controlled by a high-level ``driver'' component, or by other coordination mechanisms, such as an asynchronous event service. We describe the requirements and design of the framework, and how they were implemented in the Python language. We also illustrate the flexibility of the framework by providing examples of different types of simulations that utilize various features of the IPS.

Theoretical analysis of multiphase flow during oil-well drilling by a conservative model

Science.gov (United States)

Nicolas-Lopez, Ruben

2005-11-01

In order to decrease cost and improve drilling operations is necessary a better understood of the flow mechanisms. Therefore, it was carried out a multiphase conservative model that includes three mass equations and a momentum equation. Also, the measured geothermal gradient is utilized by state equations for estimating physical properties of the phases flowing. The mathematical model is solved by numerical conservative schemes. It is used to analyze the interaction among solid-liquid-gas phases. The circulating system consists as follow, the circulating fluid is pumped downward into the drilling pipe until the bottom of the open hole then it flows through the drill bit, and at this point formation cuttings are incorporated to the circulating fluid and carried upward to the surface. The mixture returns up to the surface by an annular flow area. The real operational conditions are fed to conservative model and the results are matched up to field measurements in several oil wells. Mainly, flow rates, drilling rate, well and tool geometries are data to estimate the profiles of pressure, mixture density, equivalent circulating density, gas fraction and solid carrying capacity. Even though the problem is very complex, the model describes, properly, the hydrodynamics of drilling techniques applied at oil fields. *Authors want to thank to Instituto Mexicano del Petroleo and Petroleos Mexicanos for supporting this research.

Investigating the NCQ scaling of elliptic flow at LHC with a multiphase transport model

Energy Technology Data Exchange (ETDEWEB)

Zheng, Liang [Central China Normal University, Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Wuhan (China); Central China Normal University, School of Mathematics and Statistics, Wuhan (China); Li, Hui; Shou, Qi-Ye; Yin, Zhong-Bao [Central China Normal University, Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Wuhan (China); Qin, Hong [Central China Normal University, School of Mathematics and Statistics, Wuhan (China)

2017-06-15

The number of constituent quark (NCQ) scaling behavior of elliptic flow has been systematically studied at the LHC energy within the framework of a multiphase transport model (AMPT) in this work. With the variation of the fragmentation parameters, collision centrality and system energy, we find that the initial conditions of parton dynamics are more important than the final state parton cascade process for the existence of NCQ scaling when the hadronic interaction is off in Pb-Pb collisions. By turning on the hadron interaction process, the impacts of hadronic evolution are found to be responsible for a significant violation to the well established scaling structure. Our study suggests that the interpretation of NCQ scaling is not only subject to the hadronization mechanism but also to the initial conditions of parton evolution as well as the hadronic interactions especially for the LHC experiments. (orig.)

Flow Rate Measurement in Multiphase Flow Rig: Radiotracer and Conventional

International Nuclear Information System (INIS)

Nazrul Hizam Yusoff; Noraishah Othman; Nurliyana Abdullah; Amirul Syafiq Mohd Yunos; Rasif Mohd Zain; Roslan Yahya

2015-01-01

Applications of radiotracer technology are prevalent throughout oil refineries worldwide, and this industry is one of the main users and beneficiaries of the technology. Radioactive tracers have been used to a great extent in many applications i.e. flow rate measurement, RTD, plant integrity evaluation and enhancing oil production in oil fields. Chemical and petrochemical plants are generally continuously operating and technically complex where the radiotracer techniques are very competitive and largely applied for troubleshooting inspection and process analysis. Flow rate measurement is a typical application of radiotracers. For flow measurements, tracer data are important, rather than the RTD models. Research is going on in refining the existing methods for single phase flow measurement, and in developing new methods for multiphase flow without sampling. The tracer techniques for single phase flow measurements are recognized as ISO standards. This paper presents technical aspect of laboratory experiments, which have been carried out using Molybdenum-99 - Mo99 (radiotracer) to study and determine the flow rate of liquid in multiphase flow rig. The multiphase flow rig consists of 58.7 m long and 20 cm diameter pipeline that can accommodate about 0.296 m 3 of liquid. Tap water was used as liquid flow in pipeline and conventional flow meters were also installed at the flow rig. The flow rate results; radiotracer and conventional flow meter were compared. The total count method was applied for radiotracer technique and showed the comparable results with conventional flow meter. (author)

Clinical significance of multiphase skeletal scintiscanning

International Nuclear Information System (INIS)

Zimmermann, P.

1984-01-01

A total of 61 patients were included in this study, which was performed to find out, if multiphase skeletal scintiscanning using 99mTc-DPD is a more accurate investigational method in terms of diagnostic differentiation than conventional scintiscanning. All patients were subjected to additional diagnostic procedures using X-rays, CT, etc. and the findings revealed were compared. In order to ensure an objective assessment of the density patterns obtained in the individual study phase (initial phase (1); vascular phase (2); soft tissue phase (3); standard phase (4)), special care was taken that only regions of similar vascularity were compared. In acute osteomyelitis, osteitis deformans according to Paget and osteoid osteoma multiphase scintiscanning yielded valuable additional information which, from the diagnostic point of view, proved to be much more meaningful than that provided by conventional scintiscanning, as very characteristic activity patterns were discernible in the initial study phases. In patients showing artificial limb infection or fractures this supplementary information was also found to be of some value, although the behaviour of activity in the initial study phases gave less conclusive evidence here than in the diseases mentioned before. In inflammatory disorders involving only minor histological changes or those of a chronic nature as well as in special forms of inflammation and artificial limb dislocation multiphase scintiscanning was not found to offer any advantages over conventional scintiscanning. (TRV) [de

Revisiting directed flow in relativistic heavy-ion collisions from a multiphase transport model

Science.gov (United States)

Guo, Chong-Qiang; Zhang, Chun-Jian; Xu, Jun

2017-12-01

We have revisited several interesting questions on how the rapidity-odd directed flow is developed in relativistic 197Au+197Au collisions at √{s_{NN}} = 200 and 39 GeV based on a multiphase transport model. As the partonic phase evolves with time, the slope of the parton directed flow at midrapidity region changes from negative to positive as a result of the later dynamics at 200 GeV, while it remains negative at 39 GeV due to the shorter life time of the partonic phase. The directed flow splitting for various quark species due to their different initial eccentricities is observed at 39 GeV, while the splitting is very small at 200GeV. From a dynamical coalescence algorithm with Wigner functions, we found that the directed flow of hadrons is a result of competition between the coalescence in momentum and coordinate space as well as further modifications by the hadronic rescatterings.

Revisiting directed flow in relativistic heavy-ion collisions from a multiphase transport model

Energy Technology Data Exchange (ETDEWEB)

Guo, Chong-Qiang; Zhang, Chun-Jian [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China); University of Chinese Academy of Sciences, Beijing (China); Xu, Jun [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China)

2017-12-15

We have revisited several interesting questions on how the rapidity-odd directed flow is developed in relativistic {sup 197}Au + {sup 197}Au collisions at √(s{sub NN}) = 200 and 39 GeV based on a multiphase transport model. As the partonic phase evolves with time, the slope of the parton directed flow at midrapidity region changes from negative to positive as a result of the later dynamics at 200 GeV, while it remains negative at 39 GeV due to the shorter life time of the partonic phase. The directed flow splitting for various quark species due to their different initial eccentricities is observed at 39 GeV, while the splitting is very small at 200 GeV. From a dynamical coalescence algorithm with Wigner functions, we found that the directed flow of hadrons is a result of competition between the coalescence in momentum and coordinate space as well as further modifications by the hadronic rescatterings. (orig.)

Temperature effects on multiphase reactions of organic molecular markers: A modeling study

Science.gov (United States)

Pratap, Vikram; Chen, Ying; Yao, Guangming; Nakao, Shunsuke

2018-04-01

Various molecular markers are used in source apportionment studies. In early studies, molecular markers were assumed to be inert. However, recent studies suggest that molecular markers can decay rapidly through multiphase reactions, which makes interpretation of marker measurements challenging. This study presents a simplified model to account for the effects of temperature and relative humidity on the lifetime of molecular markers through a shift in gas-particle partitioning as well as a change in viscosity of the condensed phase. As a model case, this study examines the stability of levoglucosan, a key marker species of biomass burning, over a wide temperature range relevant to summertime and wintertime. Despite the importance of wood combustion for space heating in winter, the lifetime of levoglucosan in wintertime is not well understood. The model predicts that in low-temperature conditions, levoglucosan predominantly remains in the particle phase, and therefore its loss due to gas-phase oxidation reactions is significantly reduced. Furthermore, the movement of the levoglucosan from the bulk of the particle to the particle surface is reduced due to low diffusivity in the semi-solid state. The simplified model developed in this study reasonably reproduces upper and lower bounds of the lifetime of levoglucosan investigated in previous studies. The model results show that the levoglucosan depletion after seven days reduces significantly from ∼98% at 25 °C to marker (lifetime > 1 week) even at 60% relative humidity irrespective of the assumed fragility parameter D that controls estimated diffusivity. The model shows that lifetime of an organic molecular marker strongly depends on assumed D especially when a semi-volatile marker is in semi-solid organic aerosol.

Pattern recognition techniques for horizontal and vertically upward multiphase flow measurement

Science.gov (United States)

Arubi, Tesi I. M.; Yeung, Hoi

2012-03-01

The oil and gas industry need for high performing and low cost multiphase meters is ever more justified given the rapid depletion of conventional oil reserves that has led oil companies to develop smaller and marginal fields and reservoirs in remote locations and deep offshore, thereby placing great demands for compact and more cost effective solutions of on-line continuous multiphase flow measurement for well testing, production monitoring, production optimisation, process control and automation. The pattern recognition approach for clamp-on multiphase measurement employed in this study provides one means for meeting this need. High speed caesium-137 radioisotope-based densitometers were installed vertically at the top of a 50.8mm and 101.6mm riser as well as horizontally at the riser base in the Cranfield University multiphase flow test facility. A comprehensive experimental campaign comprising flow conditions typical of operating conditions found in the Petroleum Industry was conducted. The application of a single gamma densitometer unit, in conjunction with pattern recognition techniques to determine both the phase volume fractions and velocities to yield the individual phase flow rates of horizontal and vertically upward multiphase flows was investigated. The pattern recognition systems were trained to map the temporal fluctuations in the multiphase mixture density with the individual phase flow rates using statistical features extracted from the gamma counts signals as their inputs. Initial results yielded individual phase flow rate predictions to within ±5% relative error for the two phase airwater flows and ±10% for three phase air-oil-water flows data.

Bayesian estimation of magma supply, storage, and eruption rates using a multiphysical volcano model: Kīlauea Volcano, 2000–2012

Science.gov (United States)

Anderson, Kyle R.; Poland, Michael

2016-01-01

Estimating rates of magma supply to the world's volcanoes remains one of the most fundamental aims of volcanology. Yet, supply rates can be difficult to estimate even at well-monitored volcanoes, in part because observations are noisy and are usually considered independently rather than as part of a holistic system. In this work we demonstrate a technique for probabilistically estimating time-variable rates of magma supply to a volcano through probabilistic constraint on storage and eruption rates. This approach utilizes Bayesian joint inversion of diverse datasets using predictions from a multiphysical volcano model, and independent prior information derived from previous geophysical, geochemical, and geological studies. The solution to the inverse problem takes the form of a probability density function which takes into account uncertainties in observations and prior information, and which we sample using a Markov chain Monte Carlo algorithm. Applying the technique to Kīlauea Volcano, we develop a model which relates magma flow rates with deformation of the volcano's surface, sulfur dioxide emission rates, lava flow field volumes, and composition of the volcano's basaltic magma. This model accounts for effects and processes mostly neglected in previous supply rate estimates at Kīlauea, including magma compressibility, loss of sulfur to the hydrothermal system, and potential magma storage in the volcano's deep rift zones. We jointly invert data and prior information to estimate rates of supply, storage, and eruption during three recent quasi-steady-state periods at the volcano. Results shed new light on the time-variability of magma supply to Kīlauea, which we find to have increased by 35–100% between 2001 and 2006 (from 0.11–0.17 to 0.18–0.28 km3/yr), before subsequently decreasing to 0.08–0.12 km3/yr by 2012. Changes in supply rate directly impact hazard at the volcano, and were largely responsible for an increase in eruption rate of 60–150% between

Multiphase composite coatings: structure and properties

International Nuclear Information System (INIS)

Yurov, V M; Guchenko, S A; Platonova, E S; Syzdykova, A Sh; Lysenko, E N

2015-01-01

The paper discusses the results of the research into the formation of ion-plasma multiphase coatings. The types of the formed structures are found to be not so diverse, as those formed, for example, in alloy crystallization. The structures observed are basically of globular type and, more rarely, of unclosed dissipative and cellular structures. It is shown that the properties of the coating formed in deposition are largely determined by its surface energy or surface tension. Since the magnitude of the surface tension (surface energy) in most cases is an additive quantity, each of the elements of the coating composition contributes to the total surface energy. In case of simultaneous sputtering of multiphase cathodes, high entropy coatings with an ordered cellular structure and improved mechanical properties are formed. (paper)

Direct numerical simulations of gas-liquid multiphase flows

CERN Document Server

Tryggvason, Grétar; Zaleski, Stéphane

2011-01-01

Accurately predicting the behaviour of multiphase flows is a problem of immense industrial and scientific interest. Modern computers can now study the dynamics in great detail and these simulations yield unprecedented insight. This book provides a comprehensive introduction to direct numerical simulations of multiphase flows for researchers and graduate students. After a brief overview of the context and history the authors review the governing equations. A particular emphasis is placed on the 'one-fluid' formulation where a single set of equations is used to describe the entire flow field and

Multiphase Return Trajectory Optimization Based on Hybrid Algorithm

Directory of Open Access Journals (Sweden)

Yi Yang

2016-01-01

Full Text Available A hybrid trajectory optimization method consisting of Gauss pseudospectral method (GPM and natural computation algorithm has been developed and utilized to solve multiphase return trajectory optimization problem, where a phase is defined as a subinterval in which the right-hand side of the differential equation is continuous. GPM converts the optimal control problem to a nonlinear programming problem (NLP, which helps to improve calculation accuracy and speed of natural computation algorithm. Through numerical simulations, it is found that the multiphase optimal control problem could be solved perfectly.

Surface Tension of Multi-phase Flow with Multiple Junctions Governed by the Variational Principle

International Nuclear Information System (INIS)

Matsutani, Shigeki; Nakano, Kota; Shinjo, Katsuhiko

2011-01-01

We explore a computational model of an incompressible fluid with a multi-phase field in three-dimensional Euclidean space. By investigating an incompressible fluid with a two-phase field geometrically, we reformulate the expression of the surface tension for the two-phase field found by Lafaurie et al. (J Comput Phys 113:134–147, 1994) as a variational problem related to an infinite dimensional Lie group, the volume-preserving diffeomorphism. The variational principle to the action integral with the surface energy reproduces their Euler equation of the two-phase field with the surface tension. Since the surface energy of multiple interfaces even with singularities is not difficult to be evaluated in general and the variational formulation works for every action integral, the new formulation enables us to extend their expression to that of a multi-phase (N-phase, N ≥ 2) flow and to obtain a novel Euler equation with the surface tension of the multi-phase field. The obtained Euler equation governs the equation for motion of the multi-phase field with different surface tension coefficients without any difficulties for the singularities at multiple junctions. In other words, we unify the theory of multi-phase fields which express low dimensional interface geometry and the theory of the incompressible fluid dynamics on the infinite dimensional geometry as a variational problem. We apply the equation to the contact angle problems at triple junctions. We computed the fluid dynamics for a two-phase field with a wall numerically and show the numerical computational results that for given surface tension coefficients, the contact angles are generated by the surface tension as results of balances of the kinematic energy and the surface energy.

Multiphase-Multifunctional Ceramic Coatings

Science.gov (United States)

2013-06-30

systems for high temperatura applications” “ Estudios de Ferroelasticidad en Sistemas Cerámicos Multifásicos para Aplicaciones en Alta Temperatura ...Ceramic Coatings Performing Organization names: Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional – Unidad Queretaro...materials, Cinvestav. Thesis: “Ferroelasticity studies in multiphase ceramic systems for high temperatura applications”. Her work mainly focused in the

It's the parameters, stupid! Moving beyond multi-model and multi-physics approaches to characterize and reduce predictive uncertainty in process-based hydrological models

Science.gov (United States)

Clark, Martyn; Samaniego, Luis; Freer, Jim

2014-05-01

Multi-model and multi-physics approaches are a popular tool in environmental modelling, with many studies focusing on optimally combining output from multiple model simulations to reduce predictive errors and better characterize predictive uncertainty. However, a careful and systematic analysis of different hydrological models reveals that individual models are simply small permutations of a master modeling template, and inter-model differences are overwhelmed by uncertainty in the choice of the parameter values in the model equations. Furthermore, inter-model differences do not explicitly represent the uncertainty in modeling a given process, leading to many situations where different models provide the wrong results for the same reasons. In other cases, the available morphological data does not support the very fine spatial discretization of the landscape that typifies many modern applications of process-based models. To make the uncertainty characterization problem worse, the uncertain parameter values in process-based models are often fixed (hard-coded), and the models lack the agility necessary to represent the tremendous heterogeneity in natural systems. This presentation summarizes results from a systematic analysis of uncertainty in process-based hydrological models, where we explicitly analyze the myriad of subjective decisions made throughout both the model development and parameter estimation process. Results show that much of the uncertainty is aleatory in nature - given a "complete" representation of dominant hydrologic processes, uncertainty in process parameterizations can be represented using an ensemble of model parameters. Epistemic uncertainty associated with process interactions and scaling behavior is still important, and these uncertainties can be represented using an ensemble of different spatial configurations. Finally, uncertainty in forcing data can be represented using ensemble methods for spatial meteorological analysis. Our systematic

Tomographic multiphase flow measurement

Energy Technology Data Exchange (ETDEWEB)

Saetre, C., E-mail: camilla@ift.uib.no [Department of Physics and Technology, University of Bergen (Norway); Michelsen Centre for Industrial Measurement Science and Technology (Norway); Johansen, G.A. [Department of Physics and Technology, University of Bergen (Norway); Michelsen Centre for Industrial Measurement Science and Technology (Norway); Tjugum, S.A. [Michelsen Centre for Industrial Measurement Science and Technology (Norway); Roxar Flow Measurement, Bergen (Norway)

2012-07-15

Measurement of multiphase flow of gas, oil and water is not at all trivial and in spite of considerable achievements over the past two decades, important challenges remain (). These are related to reducing measurement uncertainties arising from variations in the flow regime, improving long term stability and developing new means for calibration, adjustment and verification of the multiphase flow meters. This work focuses on the first two issues using multi gamma beam (MGB) measurements for identification of the type of flow regime. Further gamma ray tomographic measurements are used for reference of the gas/liquid distribution. For the MGB method one Am-241 source with principal emission at 59.5 keV is used because this relatively low energy enables efficient collimation and thereby shaping of the beams, as well as compact detectors. One detector is placed diametrically opposite the source whereas the second is positioned to the side so that this beam is close to the pipe wall. The principle is then straight forward to compare the measured intensities of these detectors and through that identify the flow pattern, i.e. the instantaneous cross-sectional gas-liquid distribution. The measurement setup also includes Compton scattering measurements, which can provide information about the changes in the water salinity for flow segments with high water liquid ratio and low gas fractions. By measuring the transmitted intensity in short time slots (<100ms), rapid regime variations are revealed. From this we can select the time sections suitable for salinity measurements. Since the salinity variations change at the time scale of hours, a running average can be performed to increase the accuracy of the measurements. Recent results of this work will be presented here. - Highlights: Black-Right-Pointing-Pointer Multiphase flow gas-fraction and flow regime measurements by multi gamma ray beams. Black-Right-Pointing-Pointer High-speed gamma ray tomograph as reference for the flow

Tomographic multiphase flow measurement

International Nuclear Information System (INIS)

Sætre, C.; Johansen, G.A.; Tjugum, S.A.

2012-01-01

Measurement of multiphase flow of gas, oil and water is not at all trivial and in spite of considerable achievements over the past two decades, important challenges remain (). These are related to reducing measurement uncertainties arising from variations in the flow regime, improving long term stability and developing new means for calibration, adjustment and verification of the multiphase flow meters. This work focuses on the first two issues using multi gamma beam (MGB) measurements for identification of the type of flow regime. Further gamma ray tomographic measurements are used for reference of the gas/liquid distribution. For the MGB method one Am-241 source with principal emission at 59.5 keV is used because this relatively low energy enables efficient collimation and thereby shaping of the beams, as well as compact detectors. One detector is placed diametrically opposite the source whereas the second is positioned to the side so that this beam is close to the pipe wall. The principle is then straight forward to compare the measured intensities of these detectors and through that identify the flow pattern, i.e. the instantaneous cross-sectional gas-liquid distribution. The measurement setup also includes Compton scattering measurements, which can provide information about the changes in the water salinity for flow segments with high water liquid ratio and low gas fractions. By measuring the transmitted intensity in short time slots (<100ms), rapid regime variations are revealed. From this we can select the time sections suitable for salinity measurements. Since the salinity variations change at the time scale of hours, a running average can be performed to increase the accuracy of the measurements. Recent results of this work will be presented here. - Highlights: ► Multiphase flow gas-fraction and flow regime measurements by multi gamma ray beams. ► High-speed gamma ray tomograph as reference for the flow pattern and gas fraction. ► Dual modality

Experimental analysis of influence of different lubricants types on the multi-phase ironing process

Directory of Open Access Journals (Sweden)

Milan Djordjević

2013-05-01

Full Text Available This paper is aimed at presenting results of an experimental analysis of the different types of lubricants influence on the multi-phase ironing process. Based on sliding of the metal strip between the two contact elements a special tribological model was adopted. The subject of experimental investigations was variations of the drawing force, contact pressure and the friction coefficient for each type of the applied lubricants. The ironing process was conducted in three-phases at the constant sliding velocity. The objective of this analysis was to compare all the applied lubricants in order to estimate their quality from the point of view of their applicability in the multi-phase ironing process.

EXPERIMENTAL ANALYSIS OF INFLUENCE OF DIFFERENT LUBRICANTS TYPES ON THE MULTI-PHASE IRONING PROCESS

Directory of Open Access Journals (Sweden)

Milan Djordjević

2013-09-01

Full Text Available This paper is aimed at presenting results of an experimental analysis of the different types of lubricants influence on the multi-phase ironing process. Based on sliding of the metal strip between the two contact elements a special tribological model was adopted. The subject of experimental investigations was variations of the drawing force, contact pressure and the friction coefficient for each type of the applied lubricants. The ironing process was conducted in three-phases at the constant sliding velocity. The objective of this analysis was to compare all the applied lubricants in order to estimate their quality from the point of view of their applicability in the multi-phase ironing process.

The Cea multi-scale and multi-physics simulation project for nuclear applications

International Nuclear Information System (INIS)

Ledermann, P.; Chauliac, C.; Thomas, J.B.

2005-01-01

Full text of publication follows. Today numerical modelling is everywhere recognized as an essential tool of capitalization, integration and share of knowledge. For this reason, it becomes the central tool of research. Until now, the Cea developed a set of scientific software allowing to model, in each situation, the operation of whole or part of a nuclear installation and these codes are largely used in nuclear industry. However, for the future, it is essential to aim for a better accuracy, a better control of uncertainties and better performance in computing times. The objective is to obtain validated models allowing accurate predictive calculations for actual complex nuclear problems such as fuel behaviour in accidental situation. This demands to master a large and interactive set of phenomena ranging from nuclear reaction to heat transfer. To this end, Cea, with industrial partners (EDF, Framatome-ANP, ANDRA) has designed an integrated platform of calculation, devoted to the study of nuclear systems, and intended at the same time for industries and scientists. The development of this platform is under way with the start in 2005 of the integrated project NURESIM, with 18 European partners. Improvement is coming not only through a multi-scale description of all phenomena but also through an innovative design approach requiring deep functional analysis which is upstream from the development of the simulation platform itself. In addition, the studies of future nuclear systems are increasingly multidisciplinary (simultaneous modelling of core physics, thermal-hydraulics and fuel behaviour). These multi-physics and multi-scale aspects make mandatory to pay very careful attention to software architecture issues. A global platform is thus developed integrating dedicated specialized platforms: DESCARTES for core physics, NEPTUNE for thermal-hydraulics, PLEIADES for fuel behaviour, SINERGY for materials behaviour under irradiation, ALLIANCES for the performance

Application and Perspectives of Multiphase Induction Motors

Directory of Open Access Journals (Sweden)

Benas Kundrotas

2012-04-01

Full Text Available The article considers the areas of applying multiphase induction motors. Their advantages against three phase motors have become the main reason for employing them in multiphase drives. The paper deals with the six-phase induction motor having two similar three phase windings in the stator shifted by 30 degrees in space and three phase windings in the rotor. Differential equations for this motor are presented and transformed to dq synchronous reference frame. The transformed equations are expressed in a matrix form and solved by MATLAB software using the Dormand-Prince (ode45 method. The transient characteristics of the torque, speed and current of the six-phase induction motor are calculated and discussed.Article in Lithuanian

How winning changes motivation in multiphase competitions.

Science.gov (United States)

Huang, Szu-Chi; Etkin, Jordan; Jin, Liyin

2017-06-01

What drives motivation in multiphase competitions? Adopting a dynamic approach, this research examines how temporary standing-being ahead of (vs. behind) one's opponent-in a multiphase competition shapes subsequent motivation. Six competitions conducted in the lab and in the field demonstrate that the impact of being ahead on contestants' motivation depends on when (i.e., in which phase of the competition) contestants learn they are in the lead. In the early phase, contestants are concerned about whether they can win; being ahead increases motivation by making winning seem more attainable. In the later phase, however, contestants are instead driven by how much additional effort they believe they need to invest; being ahead decreases motivation by reducing contestants' estimate of the remaining effort needed to win. Temporary standing thus has divergent effects on motivation in multiphase competitions, driven by a shift in contestants' main concern from the early to the later phase and thus the meaning they derive from being ahead of their opponent. By leveraging insights gained from approaching individuals' self-regulation as a dynamic process, this research advances understanding of how motivation evolves in a unique interdependent self-regulatory context. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Multiphase flows with phase change

Indian Academy of Sciences (India)

Multiphase flows with phase change are ubiquitous in many industrial sectors ranging from energy and infra-structure to specialty chemicals and pharmaceuticals. My own interest in mul- tiphase flows with phase change started more than 15 years ago when I had initiated work on riser reactor for fluid catalytic cracking and ...

Black hole feedback in a multiphase interstellar medium

Science.gov (United States)

Bourne, Martin A.; Nayakshin, Sergei; Hobbs, Alexander

2014-07-01

Ultrafast outflows (UFOs) from supermassive black holes (SMBHs) are thought to regulate the growth of SMBHs and host galaxies, resulting in a number of observational correlations. We present high-resolution numerical simulations of the impact of a thermalized UFO on the ambient gas in the inner part of the host galaxy. Our results depend strongly on whether the gas is homogeneous or clumpy. In the former case all of the ambient gas is driven outward rapidly as expected based on commonly used energy budget arguments, while in the latter the flows of mass and energy de-couple. Carrying most of the energy, the shocked UFO escapes from the bulge via paths of least resistance, taking with it only the low-density phase of the host. Most of the mass is however in the high-density phase, and is affected by the UFO much less strongly, and may even continue to flow inwards. We suggest that the UFO energy leakage through the pores in the multiphase interstellar medium (ISM) may explain why observed SMBHs are so massive despite their overwhelmingly large energy production rates. The multiphase ISM effects reported here are probably under-resolved in cosmological simulations but may be included in prescriptions for active galactic nuclei feedback in future simulations and in semi-analytical models.

Heat transfer model for quenching by submerging

International Nuclear Information System (INIS)

Passarella, D N; Varas, F; MartIn, E B

2011-01-01

In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.

Heat transfer model for quenching by submerging

Energy Technology Data Exchange (ETDEWEB)

Passarella, D N; Varas, F [Departamento de Matematica Aplicada II, E.T.S. de Ing. de Telecomunicacion, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain); MartIn, E B, E-mail: diego@dma.uvigo.es, E-mail: fvaras@uvigo.es, E-mail: emortega@uvigo.es [Area de Mecanica de Fluidos, E.T.S. de Ing. Industriales, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain)

2011-05-01

In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.

ACME - Algorithms for Contact in a Multiphysics Environment API Version 1.0

International Nuclear Information System (INIS)

BROWN, KEVIN H.; SUMMERS, RANDALL M.; GLASS, MICHEAL W.; GULLERUD, ARNE S.; HEINSTEIN, MARTIN W.; JONES, REESE E.

2001-01-01

An effort is underway at Sandia National Laboratories to develop a library of algorithms to search for potential interactions between surfaces represented by analytic and discretized topological entities. This effort is also developing algorithms to determine forces due to these interactions for transient dynamics applications. This document describes the Application Programming Interface (API) for the ACME (Algorithms for Contact in a Multiphysics Environment) library

Stability Analysis of Reactive Multiphase Slug Flows in Microchannels

Directory of Open Access Journals (Sweden)

Alejandro A. Munera Parra

2014-05-01

Full Text Available Conducting multiphase reactions in micro-reactors is a promising strategy for intensifying chemical and biochemical processes. A major unresolved challenge is to exploit the considerable benefits offered by micro-scale operation for industrial scale throughputs by numbering-up whilst retaining the underlying advantageous flow characteristics of the single channel system in multiple parallel channels. Fabrication and installation tolerances in the individual micro-channels result in different pressure losses and, thus, a fluid maldistribution. In this work, an additional source of maldistribution, namely the flow multiplicities, which can arise in a multiphase reactive or extractive flow in otherwise identical micro-channels, was investigated. A detailed experimental and theoretical analysis of the flow stability with and without reaction for both gas-liquid and liquid-liquid slug flow has been developed. The model has been validated using the extraction of acetic acid from n-heptane with the ionic liquid 1-Ethyl-3-methylimidazolium ethyl sulfate. The results clearly demonstrate that the coupling between flow structure, the extent of reaction/extraction and pressure drop can result in multiple operating states, thus, necessitating an active measurement and control concept to ensure uniform behavior and optimal performance.

A multi-physics code system based on ANC9, VIPRE-W and BOA for CIPS evaluation

Energy Technology Data Exchange (ETDEWEB)

Zhang, B.; Sung, Y.; Secker, J.; Beard, C.; Hilton, P.; Wang, G.; Oelrich, R.; Karoutas, Z.; Sung, Y. [Westinghouse Electric Company LLC, Pittsburgh (United States)

2011-07-01

This paper summarizes the development of a multi-physics code system for evaluation of Crud Induced Power Shift (CIPS) phenomenon experienced in some Pressurized Water Reactors (PWR). CIPS is an unexpected change in reactor core axial power distribution, caused by boron compounds in crud deposited in the high power fuel assemblies undergoing subcooled boiling. As part of the Consortium for Advanced Simulation of Light Water Reactors (CASL) sponsored by the US Department of Energy (DOE), this paper describes the initial linkage and application of a multi-physics code system ANC9/VIPRE-W/BOA for evaluating changes in core power distributions due to boron deposited in crud. The initial linkage of the code system along with the application results will be the base for the future CASL development. (author)

A multi-physics code system based on ANC9, VIPRE-W and BOA for CIPS evaluation

International Nuclear Information System (INIS)

Zhang, B.; Sung, Y.; Secker, J.; Beard, C.; Hilton, P.; Wang, G.; Oelrich, R.; Karoutas, Z.; Sung, Y.

2011-01-01

This paper summarizes the development of a multi-physics code system for evaluation of Crud Induced Power Shift (CIPS) phenomenon experienced in some Pressurized Water Reactors (PWR). CIPS is an unexpected change in reactor core axial power distribution, caused by boron compounds in crud deposited in the high power fuel assemblies undergoing subcooled boiling. As part of the Consortium for Advanced Simulation of Light Water Reactors (CASL) sponsored by the US Department of Energy (DOE), this paper describes the initial linkage and application of a multi-physics code system ANC9/VIPRE-W/BOA for evaluating changes in core power distributions due to boron deposited in crud. The initial linkage of the code system along with the application results will be the base for the future CASL development. (author)

Proceedings of submicron multiphase materials

International Nuclear Information System (INIS)

Baney, R.; Gilliom, L.; Hirano, S.I.; Schmidt, H.

1992-01-01

This book contains the papers presented at Symposium R of the spring 1992 Materials Research Society meeting held in San Francisco, California. The title of the symposium, Submicron Multiphase Materials, was selected by the organizers to encompass the realm of composite materials from those smaller than conventional fiber matrix composites to those with phase separation dimensions approaching molecular dimensions. The development of composite materials is as old as the development of materials. Humans quickly learned that, by combining materials, the best properties of each can be realized and that, in fact, synergistic effects often arise. For example, chopped straw was used by the Israelites to limit cracking in bricks. The famed Japanese samurai swords were multilayers of hard oxide and tough ductile materials. One also finds in nature examples of composite materials. These range form bone to wood, consisting of a hard phase which provides strength and stiffness and a softer phase for toughness. Advanced composites are generally thought of as those which are based on a high modulus, discontinuous, chopped or woven fiber phase and a continuous polymer phase. In multiphase composites, dimensions can range from meters in materials such as steel rod-reinforced concrete structures to angstroms. In macrophase separated composite materials, properties frequently follow the rule of mixtures with the properties approximating the arithmetic mean of the properties of each individual phase, if there is good coupling between the phases. As the phases become smaller, the surface to volume ratio grows in importance with respect to properties. Interfacial and interphase phenomena being to dominate. Surface free energies play an ever increasing role in controlling properties. In recent years, much research in materials science has been directed at multiphase systems where phase separations are submicron in at least some dimension

A summary of methods for approximating salt creep and disposal room closure in numerical models of multiphase flow

Energy Technology Data Exchange (ETDEWEB)

Freeze, G.A.; Larson, K.W. [INTERA, Inc., Albuquerque, NM (United States); Davies, P.B. [Sandia National Labs., Albuquerque, NM (United States)

1995-10-01

Eight alternative methods for approximating salt creep and disposal room closure in a multiphase flow model of the Waste Isolation Pilot Plant (WIPP) were implemented and evaluated: Three fixed-room geometries three porosity functions and two fluid-phase-salt methods. The pressure-time-porosity line interpolation method is the method used in current WIPP Performance Assessment calculations. The room closure approximation methods were calibrated against a series of room closure simulations performed using a creep closure code, SANCHO. The fixed-room geometries did not incorporate a direct coupling between room void volume and room pressure. The two porosity function methods that utilized moles of gas as an independent parameter for closure coupling. The capillary backstress method was unable to accurately simulate conditions of re-closure of the room. Two methods were found to be accurate enough to approximate the effects of room closure; the boundary backstress method and pressure-time-porosity line interpolation. The boundary backstress method is a more reliable indicator of system behavior due to a theoretical basis for modeling salt deformation as a viscous process. It is a complex method and a detailed calibration process is required. The pressure lines method is thought to be less reliable because the results were skewed towards SANCHO results in simulations where the sequence of gas generation was significantly different from the SANCHO gas-generation rate histories used for closure calibration. This limitation in the pressure lines method is most pronounced at higher gas-generation rates and is relatively insignificant at lower gas-generation rates. Due to its relative simplicity, the pressure lines method is easier to implement in multiphase flow codes and simulations have a shorter execution time.

A summary of methods for approximating salt creep and disposal room closure in numerical models of multiphase flow

International Nuclear Information System (INIS)

Freeze, G.A.; Larson, K.W.; Davies, P.B.

1995-10-01

Eight alternative methods for approximating salt creep and disposal room closure in a multiphase flow model of the Waste Isolation Pilot Plant (WIPP) were implemented and evaluated: Three fixed-room geometries three porosity functions and two fluid-phase-salt methods. The pressure-time-porosity line interpolation method is the method used in current WIPP Performance Assessment calculations. The room closure approximation methods were calibrated against a series of room closure simulations performed using a creep closure code, SANCHO. The fixed-room geometries did not incorporate a direct coupling between room void volume and room pressure. The two porosity function methods that utilized moles of gas as an independent parameter for closure coupling. The capillary backstress method was unable to accurately simulate conditions of re-closure of the room. Two methods were found to be accurate enough to approximate the effects of room closure; the boundary backstress method and pressure-time-porosity line interpolation. The boundary backstress method is a more reliable indicator of system behavior due to a theoretical basis for modeling salt deformation as a viscous process. It is a complex method and a detailed calibration process is required. The pressure lines method is thought to be less reliable because the results were skewed towards SANCHO results in simulations where the sequence of gas generation was significantly different from the SANCHO gas-generation rate histories used for closure calibration. This limitation in the pressure lines method is most pronounced at higher gas-generation rates and is relatively insignificant at lower gas-generation rates. Due to its relative simplicity, the pressure lines method is easier to implement in multiphase flow codes and simulations have a shorter execution time

A modelling study of the multiphase leakage flow from pressurised CO{sub 2} pipeline

Energy Technology Data Exchange (ETDEWEB)

Zhou, Xuejin; Li, Kang [Department of Safety Science Engineering & State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tu, Ran [College of Mechanical Engineering and Automation, Huaqiao University, Jimei, Xiamen 361000 (China); Yi, Jianxin; Xie, Qiyuan [Department of Safety Science Engineering & State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026 (China); Jiang, Xi, E-mail: x.jiang@lancaster.ac.uk [Engineering Department, Lancaster University, Lancaster LA1 4YR (United Kingdom)

2016-04-05

Highlights: • A simplified model for CO{sub 2} decompression from high pressure pipelines is proposed. • The multiphase fluid was considered as a homogeneous equilibrium mixture. • Different real gas equations of state were incorporated into the model. • Detailed chocked flow calculation with capillary tube assumption was performed. • The model was validated against experimental data with discrepancies discussed. - Abstract: The accidental leakage is one of the main risks during the pipeline transportation of high pressure CO{sub 2}. The decompression process of high pressure CO{sub 2} involves complex phase transition and large variations of the pressure and temperature fields. A mathematical method based on the homogeneous equilibrium mixture assumption is presented for simulating the leakage flow through a nozzle in a pressurised CO{sub 2} pipeline. The decompression process is represented by two sub-models: the flow in the pipe is represented by the blowdown model, while the leakage flow through the nozzle is calculated with the capillary tube assumption. In the simulation, two kinds of real gas equations of state were employed in this model instead of the ideal gas equation of state. Moreover, results of the flow through the nozzle and measurement data obtained from laboratory experiments of pressurised CO{sub 2} pipeline leakage were compared for the purpose of validation. The thermodynamic processes of the fluid both in the pipeline and the nozzle were described and analysed.

Development of an Efficient Meso- scale Multi-phase Flow Solver in Nuclear Applications

Energy Technology Data Exchange (ETDEWEB)

Lee, Taehun [City Univ. (CUNY), NY (United States)

2015-10-20

The proposed research aims at formulating a predictive high-order Lattice Boltzmann Equation for multi-phase flows relevant to nuclear energy related application - namely, saturated and sub-cooled boiling in reactors, and liquid- liquid mixing and extraction for fuel cycle separation. An efficient flow solver will be developed based on the Finite Element based Lattice Boltzmann Method (FE- LBM), accounting for phase-change heat transfer and capable of treating multiple phases over length scales from the submicron to the meter. A thermal LBM will be developed in order to handle adjustable Prandtl number, arbitrary specific heat ratio, a wide range of temperature variations, better numerical stability during liquid-vapor phase change, and full thermo-hydrodynamic consistency. Two-phase FE-LBM will be extended to liquid–liquid–gas multi-phase flows for application to high-fidelity simulations building up from the meso-scale up to the equipment sub-component scale. While several relevant applications exist, the initial applications for demonstration of the efficient methods to be developed as part of this project include numerical investigations of Critical Heat Flux (CHF) phenomena in nuclear reactor fuel bundles, and liquid-liquid mixing and interfacial area generation for liquid-liquid separations. In addition, targeted experiments will be conducted for validation of this advanced multi-phase model.

Multiphase simulation of mine waters and aqueous leaching processes

Directory of Open Access Journals (Sweden)

Pajarre Risto

2016-01-01

Full Text Available Managing of large amounts of water in mining and mineral processing sites remains a concern in both actively operated and closed mining areas. When the mining site with its metal or concentrate producing units is operational, the challenge is to find either ways for economical processing with maximum yields, while minimizing the environmental impact of the water usage and waste salt treatments. For safe closure of the site, the environmental control of possible drainage will be needed. For both challenges, the present-day multiphase process simulations tools can be used to provide improved accuracy and better economy in controlling the smooth and environmentally sound operation of the plant. One of the pioneering studies in using the multiphase thermodynamic software in simulation of hydrometallurgical processes was that of Koukkari et al. [1]. The study covered the use of Solgasmix equilibrium software for a number of practical acid digesters. The models were made for sulfuric acid treatments in titania pigment production and in NPK fertilizer manufacturing. During the past two decades the extensive data assessment has taken place particularly in geochemistry and a new versions of geochemical multiphase equilibrium software has been developed. On the other hand, there has been some progress in development of the process simulation software in all the aforementioned fields. Thus, the thermodynamic simulation has become a tool of great importance in development of hydrometallurgical processes. The presentation will cover three example cases of either true pilot or industrial systems including a South African acid mine water drainage treatment, hydrometallurgical extraction of rare earths from uranium leachate in Russia and a multistage process simulation of a Finnish heap leaching mine with its subsequent water treatment system.

New approach to multiphase equilibria: application to high-pressure physics problems

International Nuclear Information System (INIS)

Ree, F.H.

1985-06-01

A multiphase, multicomponent equation-of-state (EOS) model based on first principles of statistical mechanics is described. The model has been used to study fluid-fluid phase separations in binary (H 2 -He, Ar-Ne, Xe-He, and N 2 -H 2 O) and ternary or more complex systems involving species with C, H, N, and O atoms. Results of these calculations and a brief description of a new theory which can simultaneously describe both solid and fluid EOS properties are given. 26 refs., 4 figs

On the Grand Challenges in Physical Petrology: the Multiphase Crossroads

Science.gov (United States)

Bergantz, G. W.

2014-12-01

Rapid progress in experimental, micro-analytical and textural analysis at the crystal scale has produced an unprecedented record of magmatic processes. However an obstacle to further progress is the lack of understanding of how mass, energy and momentum flux associated with crystal-rich, open-system events produces identifiable outcomes. Hence developing a physically-based understanding of magmatic systems linking micro-scale petrological observations with a physical template operating at the macro-scale presents a so-called "Grand Challenge." The essence of this challenge is that magmatic systems have characteristic length and feedback scales between those accessible by classical continuum and discrete methods. It has become increasingly obvious that the old-school continuum methods have limited resolution and power of explanation for multiphase (real) magma dynamics. This is, in part, because in crystal-rich systems the deformation is non-affine, and so the concept of constitutive behavior is less applicable and likely not even relevant, especially if one is interested in the emergent character of micro-scale processes. One expression of this is the cottage industry of proposing viscosity laws for magmas, which serves as "blunt force" de facto corrections for what is intrinsically multiphase behavior. Even in more fluid-rich systems many of these laws are not suitable for use in the very transport theories they aim to support. The alternative approach is the discrete method, where multiphase interactions are explicitly resolved. This is a daunting prospect given the numbers of crystals in magmas. But perhaps all crystals don't need to be modeled. I will demonstrate how discrete methods can recover critical state behavior, resolve crystal migration, the onset of visco-elastic behavior such as melt-present shear bands which sets the large-scale mixing volumes, some of the general morpho-dynamics that underlies purported rheological models, and transient controls on

Application of neutron radiography to visualization of multiphase flows

International Nuclear Information System (INIS)

Takenaka, N.; Fujii, T.; Nishizaki, K.; Asano, H.; Ono, A.; Sonoda, K.; Akagawa, K.

1990-01-01

Visualizations by real-time neutron radiography are demonstrated of various flow patterns of nitrogen gas-water two-phase flow in a stainless-steel tube, water inverted annular flow in a stainless-steel tube, flashing flow in an aluminium nozzle and fluidized bed in aluminium tube and vessels. Photographs every 1/60 s are presented by an image processing method to show the dynamic behaviours of the various flow patterns. It is shown that this visualization method can be applied efficiently to multiphase flow researches and will be applicable to multiphase flows in industrial machines. (author)

A compositional multiphase model for groundwater contamination by petroleum products: 1. Theoretical considerations

Science.gov (United States)

Corapcioglu, M. Yavuz; Baehr, Arthur L.

1987-01-01

A mathematical model is developed to describe the fate of hydrocarbon constituents of petroleum products introduced to soils as an immiscible liquid from sources such as leaking underground storage tanks and ruptured pipelines. The problem is one of multiphase transport (oil (immiscible), air, and water phases) of a reactive contaminant with constituents such as benzene, toluene, and xylene found in refined petroleum products like gasoline. In the unsaturated zone, transport of each constituent can occur as a solute in the water phase, vapor in the air phase, and as an unaltered constituent in the oil phase. Additionally, the model allows for adsorption. Molecular transformations, microbially mediated or abiotic, are incorporated as sink terms in the conservation of mass equations. An equilibrium approximation, applicable to any immiscible organic contaminant is applied to partition constituent mass between the air, oil, water, and adsorbed phases for points in the region where the oil phase exists. Outside the oil plume the equilibrium approximation takes on a simpler form to partition constituent mass between the air, water, and adsorbed phases only. Microbial degradation of petroleum products is first discussed in a general model, then the conservation of mass equation for oxygen is incorporated into the analysis which takes advantage of the key role played by oxygen in the metabolism of hydrocarbon utilizing microbes in soil environments. Approximations to two subproblems, oil plume establishment in the unsaturated zone, and solute and vapor transport subsequent to immiscible plume establishment are then developed from the general model.

Uncertainty Quantification of Multi-Phase Closures

Energy Technology Data Exchange (ETDEWEB)

Nadiga, Balasubramanya T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baglietto, Emilio [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2017-10-27

In the ensemble-averaged dispersed phase formulation used for CFD of multiphase ows in nuclear reactor thermohydraulics, closures of interphase transfer of mass, momentum, and energy constitute, by far, the biggest source of error and uncertainty. Reliable estimators of this source of error and uncertainty are currently non-existent. Here, we report on how modern Validation and Uncertainty Quanti cation (VUQ) techniques can be leveraged to not only quantify such errors and uncertainties, but also to uncover (unintended) interactions between closures of di erent phenomena. As such this approach serves as a valuable aide in the research and development of multiphase closures. The joint modeling of lift, drag, wall lubrication, and turbulent dispersion|forces that lead to tranfer of momentum between the liquid and gas phases|is examined in the frame- work of validation of the adiabatic but turbulent experiments of Liu and Banko , 1993. An extensive calibration study is undertaken with a popular combination of closure relations and the popular k-ϵ turbulence model in a Bayesian framework. When a wide range of super cial liquid and gas velocities and void fractions is considered, it is found that this set of closures can be validated against the experimental data only by allowing large variations in the coe cients associated with the closures. We argue that such an extent of variation is a measure of uncertainty induced by the chosen set of closures. We also nd that while mean uid velocity and void fraction pro les are properly t, uctuating uid velocity may or may not be properly t. This aspect needs to be investigated further. The popular set of closures considered contains ad-hoc components and are undesirable from a predictive modeling point of view. Consequently, we next consider improvements that are being developed by the MIT group under CASL and which remove the ad-hoc elements. We use non-intrusive methodologies for sensitivity analysis and calibration (using

A combined single-multiphase flow formulation of the premixing phase using the level set method

International Nuclear Information System (INIS)

Leskovar, M.; Marn, J.

1999-01-01

The premixing phase of a steam explosion covers the interaction of the melt jet or droplets with the water prior to any steam explosion occurring. To get a better insight of the hydrodynamic processes during the premixing phase beside hot premixing experiments, where the water evaporation is significant, also cold isothermal premixing experiments are performed. The specialty of isothermal premixing experiments is that three phases are involved: the water, the air and the spheres phase, but only the spheres phase mixes with the other two phases whereas the water and air phases do not mix and remain separated by a free surface. Our idea therefore was to treat the isothermal premixing process with a combined single-multiphase flow model. In this combined model the water and air phase are treated as a single phase with discontinuous phase properties at the water air interface, whereas the spheres are treated as usually with a multiphase flow model, where the spheres represent the dispersed phase and the common water-air phase represents the continuous phase. The common water-air phase was described with the front capturing method based on the level set formulation. In the level set formulation, the boundary of two-fluid interfaces is modeled as the zero set of a smooth signed normal distance function defined on the entire physical domain. The boundary is then updated by solving a nonlinear equation of the Hamilton-Jacobi type on the whole domain. With this single-multiphase flow model the Queos isothermal premixing Q08 has been simulated. A numerical analysis using different treatments of the water-air interface (level set, high-resolution and upwind) has been performed for the incompressible and compressible case and the results were compared to experimental measurements.(author)

Design and fabrication of biomimetic multiphased scaffolds for ligament-to-bone fixation.

Science.gov (United States)

He, Jiankang; Zhang, Wenyou; Liu, Yaxiong; Li, Xiang; Li, Dichen; Jin, Zhongmin

2015-05-01

Conventional ligament grafts with single material composition cannot effectively integrate with the host bones due to mismatched properties and eventually affect their long-term function in vivo. Here we presented a multi-material strategy to design and fabricate composite scaffolds including ligament, interface and bone multiphased regions. The interface region consists of triphasic layers with varying material composition and porous structure to mimic native ligament-to-bone interface while the bone region contains polycaprolactone (PCL) anchor and microchanneled ceramic scaffolds to potentially provide combined mechanical and biological implant-bone fixation. Finite element analysis (FEA) demonstrated that the multiphased scaffolds with interference value smaller than 0.5 mm could avoid the fracture of ceramic scaffold during the implantation process, which was validated by in-vitro implanting the multiphased scaffolds into porcine joint bones. Pull-out experiment showed that the initial fixation between the multiphased scaffolds with 0.47 mm interference and the host bones could withstand the maximum force of 360.31±97.51 N, which can be improved by reinforcing the ceramic scaffolds with biopolymers. It is envisioned that the multiphased scaffold could potentially induce the regeneration of a new bone as well as interfacial tissue with the gradual degradation of the scaffold and subsequently realize long-term biological fixation of the implant with the host bone. Copyright © 2015 Elsevier B.V. All rights reserved.

Optimization and parallelization of the thermal–hydraulic subchannel code CTF for high-fidelity multi-physics applications

International Nuclear Information System (INIS)

Salko, Robert K.; Schmidt, Rodney C.; Avramova, Maria N.

2015-01-01

parallel, two additional libraries are currently needed: MPI, for inter-processor message passing, and the Parallel Extensible Toolkit for Scientific Computation (PETSc), which is used to solve the global pressure matrix in parallel. Results presented include a set of testing and verification calculations and performance tests assessing parallel scaling characteristics up to a full-core, pincell-resolved model of a PWR core containing 193 17 × 17 assemblies under hot full-power conditions. This model, representative of Watts Bar Unit 1 and containing about 56,000 pins, was modeled with roughly 59,000 subchannels, leading to about 2.8 million thermal–hydraulic control volumes in total. Results demonstrate that CTF can now perform full-core analysis of a PWR (not previously possible owing to excessively long runtimes and memory requirements) on the order of 20 min. This new capability not only is useful to stand-alone CTF users, but also is being leveraged in support of coupled code multi-physics calculations being done in the CASL program

Multiphase turbulence mechanisms identification from consistent analysis of direct numerical simulation data

Directory of Open Access Journals (Sweden)

Ben Magolan

2017-09-01

Full Text Available Direct Numerical Simulation (DNS serves as an irreplaceable tool to probe the complexities of multiphase flow and identify turbulent mechanisms that elude conventional experimental measurement techniques. The insights unlocked via its careful analysis can be used to guide the formulation and development of turbulence models used in multiphase computational fluid dynamics simulations of nuclear reactor applications. Here, we perform statistical analyses of DNS bubbly flow data generated by Bolotnov (Reτ = 400 and Lu–Tryggvason (Reτ = 150, examining single-point statistics of mean and turbulent liquid properties, turbulent kinetic energy budgets, and two-point correlations in space and time. Deformability of the bubble interface is shown to have a dramatic impact on the liquid turbulent stresses and energy budgets. A reduction in temporal and spatial correlations for the streamwise turbulent stress (uu is also observed at wall-normal distances of y+ = 15, y/δ = 0.5, and y/δ = 1.0. These observations motivate the need for adaptation of length and time scales for bubble-induced turbulence models and serve as guidelines for future analyses of DNS bubbly flow data.

A capacitive CMOS-MEMS sensor designed by multi-physics simulation for integrated CMOS-MEMS technology

Science.gov (United States)

Konishi, Toshifumi; Yamane, Daisuke; Matsushima, Takaaki; Masu, Kazuya; Machida, Katsuyuki; Toshiyoshi, Hiroshi

2014-01-01

This paper reports the design and evaluation results of a capacitive CMOS-MEMS sensor that consists of the proposed sensor circuit and a capacitive MEMS device implemented on the circuit. To design a capacitive CMOS-MEMS sensor, a multi-physics simulation of the electromechanical behavior of both the MEMS structure and the sensing LSI was carried out simultaneously. In order to verify the validity of the design, we applied the capacitive CMOS-MEMS sensor to a MEMS accelerometer implemented by the post-CMOS process onto a 0.35-µm CMOS circuit. The experimental results of the CMOS-MEMS accelerometer exhibited good agreement with the simulation results within the input acceleration range between 0.5 and 6 G (1 G = 9.8 m/s2), corresponding to the output voltages between 908.6 and 915.4 mV, respectively. Therefore, we have confirmed that our capacitive CMOS-MEMS sensor and the multi-physics simulation will be beneficial method to realize integrated CMOS-MEMS technology.

A Two-Dimensional Multiphysics Coupling Model of a Middle and Low Temperature Solar Receiver/Reactor for Methanol Decomposition

Directory of Open Access Journals (Sweden)

Yanjuan Wang

2017-10-01

Full Text Available Abstract: In this paper, the endothermic methanol decomposition reaction is used to obtain syngas by transforming middle and low temperature solar energy into chemical energy. A two-dimensional multiphysics coupling model of a middle and low temperature of 150~300 °C solar receiver/reactor was developed, which couples momentum equation in porous catalyst bed, the governing mass conservation with chemical reaction, and energy conservation incorporating conduction/convection/radiation heat transfer. The complex thermochemical conversion process of the middle and low temperature solar receiver/reactor (MLTSRR system was analyzed. The numerical finite element method (FEM model was validated by comparing it with the experimental data and a good agreement was obtained, revealing that the numerical FEM model is reliable. The characteristics of chemical reaction, coupled heat transfer, the components of reaction products, and the temperature fields in the receiver/reactor were also revealed and discussed. The effects of the annulus vacuum space and the glass tube on the performance of the solar receiver/reactor were further studied. It was revealed that when the direct normal irradiation increases from 200 W/m2 to 800 W/m2, the theoretical efficiency of solar energy transformed into chemical energy can reach 0.14–0.75. When the methanol feeding rate is 13 kg/h, the solar flux increases from 500 W/m2 to 1000 W/m2, methanol conversion can fall by 6.8–8.9% with air in the annulus, and methanol conversion can decrease by 21.8–28.9% when the glass is removed from the receiver/reactor.

TOUGH2: A general-purpose numerical simulator for multiphase nonisothermal flows

Energy Technology Data Exchange (ETDEWEB)

Pruess, K. [Lawrence Berkeley Lab., CA (United States)

1991-06-01

Numerical simulators for multiphase fluid and heat flows in permeable media have been under development at Lawrence Berkeley Laboratory for more than 10 yr. Real geofluids contain noncondensible gases and dissolved solids in addition to water, and the desire to model such `compositional` systems led to the development of a flexible multicomponent, multiphase simulation architecture known as MULKOM. The design of MULKOM was based on the recognition that the mass-and energy-balance equations for multiphase fluid and heat flows in multicomponent systems have the same mathematical form, regardless of the number and nature of fluid components and phases present. Application of MULKOM to different fluid mixtures, such as water and air, or water, oil, and gas, is possible by means of appropriate `equation-of-state` (EOS) modules, which provide all thermophysical and transport parameters of the fluid mixture and the permeable medium as a function of a suitable set of primary thermodynamic variables. Investigations of thermal and hydrologic effects from emplacement of heat-generating nuclear wastes into partially water-saturated formations prompted the development and release of a specialized version of MULKOM for nonisothermal flow of water and air, named TOUGH. TOUGH is an acronym for `transport of unsaturated groundwater and heat` and is also an allusion to the tuff formations at Yucca Mountain, Nevada. The TOUGH2 code is intended to supersede TOUGH. It offers all the capabilities of TOUGH and includes a considerably more general subset of MULKOM modules with added capabilities. The paper briefly describes the simulation methodology and user features.

Speed-sensorless control strategy for multi-phase induction generator in wind energy conversion systems

Directory of Open Access Journals (Sweden)

Dumnić Boris P.

2016-01-01

Full Text Available Renewable energy sources, especially wind energy conversion systems (WECS, exhibit constant growth. Increase in power and installed capacity led to advances in WECS topologies. Multi-phase approach presents a new development direction, with several key advantages over three-phase systems. Paired with a sensorless control strategy, multi-phase machines are expected to take primacy over standard solutions. This paper presents speed sensorless vector control of an asymmetrical six-phase induction generator based on a model reference adaptive system (MRAS. Suggested topology and developed control algorithm show that sensorless control can yield appropriate dynamic characteristics for the use in WECS with increase in reliability and robustness. [Projekat Ministarstva nauke Republike Srbije, br. III 042004: Smart Electricity Distribution Grids Based on Distribution Management System and Distributed Generation

Integrated modelling in materials and process technology

DEFF Research Database (Denmark)

Hattel, Jesper Henri

2008-01-01

Integrated modelling of entire process sequences and the subsequent in-service conditions, and multiphysics modelling of the single process steps are areas that increasingly support optimisation of manufactured parts. In the present paper, three different examples of modelling manufacturing...... processes from the viewpoint of combined materials and process modelling are presented: solidification of thin walled ductile cast iron, integrated modelling of spray forming and multiphysics modelling of friction stir welding. The fourth example describes integrated modelling applied to a failure analysis...

Ω and ϕ in Au + Au collisions at and 11.5 GeV from a multiphase transport model

Science.gov (United States)

Ye, Y. J.; Chen, J. H.; Ma, Y. G.; Zhang, S.; Zhong, C.

2017-08-01

Within the framework of a multiphase transport model, we study the production and properties of Ω and ϕ in Au + Au collisions with a new set of parameters for and with the original set of parameters for . The AMPT model with string melting provides a reasonable description at , while the default AMPT model describes the data well at . This indicates that the system created at top RHIC energy is dominated by partonic interactions, while hadronic interactions become important at lower beam energy, such as . The comparison of N(Ω++Ω-)/[2N(ϕ)] ratio between data and calculations further supports the argument. Our calculations can generally describe the data of nuclear modification factor as well as elliptic flow. Supported by National Natural Science Foundation of China (11421505, 11520101004, 11220101005, 11275250, 11322547), Major State Basic Research Development Program in China (2014CB845400, 2015CB856904) and Key Research Program of Frontier Sciences of CAS (QYZDJSSW-SLH002)

NO2-initiated multiphase oxidation of SO2 by O2 on CaCO3 particles

Science.gov (United States)

Yu, Ting; Zhao, Defeng; Song, Xiaojuan; Zhu, Tong

2018-05-01

The reaction of SO2 with NO2 on the surface of aerosol particles has been suggested to be important in sulfate formation during severe air pollution episodes in China. However, we found that the direct oxidation of SO2 by NO2 was slow and might not be the main reason for sulfate formation in ambient air. In this study, we investigated the multiphase reaction of SO2 with an O2 / NO2 mixture on single CaCO3 particles using Micro-Raman spectroscopy. The reaction converted the CaCO3 particle to a Ca(NO3)2 droplet, with CaSO4 ⚫ 2H2O solid particles embedded in it, which constituted a significant fraction of the droplet volume at the end of the reaction. The reactive uptake coefficient of SO2 for sulfate formation was on the order of 10-5, which was higher than that for the multiphase reaction of SO2 directly with NO2 by 2-3 orders of magnitude. According to our observations and the literature, we found that in the multiphase reaction of SO2 with the O2 / NO2 mixture, O2 was the main oxidant of SO2 and was necessary for radical chain propagation. NO2 acted as the initiator of radical formation, but not as the main oxidant. The synergy of NO2 and O2 resulted in much faster sulfate formation than the sum of the reaction rates with NO2 and with O2 alone. We estimated that the multiphase oxidation of SO2 by O2 initiated by NO2 could be an important source of sulfate and a sink of SO2, based on the calculated lifetime of SO2 regarding the loss through the multiphase reaction versus the loss through the gas-phase reaction with OH radicals. Parameterization of the reactive uptake coefficient of the reaction observed in our laboratory for further model simulation is needed, as well as an integrated assessment based on field observations, laboratory study results, and model simulations to evaluate the importance of the reaction in ambient air during severe air pollution episodes, especially in China.

Multiphase Microstructure in a Metastability-Assisted Medium Carbon Alloy Steel

Science.gov (United States)

Liu, Cheng; Cui, Xixi; Yang, Chen

2018-05-01

A medium carbon alloy steel is processed by austenizing at 900 °C for 30 min, then rapid quenching into a patented quenching liquid and holding at 170 °C for 5 min, finally isothermally holding at 250 °C for different times. The morphology and mechanical properties are performed by using optical microscopy and scanning electron microscopy. A multiphase microstructure characterized by a mixture of lenticular prior martensite (PM), fine needle bainitic ferrite and filmy retained austenite (RA) is obtained. It is found that the PM formed firstly upon quenching can accelerate the subsequent bainitic transformation and promote refinement of multiphase colonies. The results show that an optimum mechanical property of a 4000.9 MPa bending strength and a 2030 MPa tensile strength is achieved at 250 °C for 120 min, which is attributed to the multiphase microstructural characteristics and a high product of the volume fraction of RA and the carbon content of austenite.

Variational continuum multiphase poroelasticity theory and applications

CERN Document Server

Serpieri, Roberto

2017-01-01

This book collects the theoretical derivation of a recently presented general variational macroscopic continuum theory of multiphase poroelasticity (VMTPM), together with its applications to consolidation and stress partitioning problems of interest in several applicative engineering contexts, such as in geomechanics and biomechanics. The theory is derived based on a purely-variational deduction, rooted in the least-Action principle, by considering a minimal set of kinematic descriptors. The treatment herein considered keeps a specific focus on the derivation of most general medium-independent governing equations. It is shown that VMTPM recovers paradigms of consolidated use in multiphase poroelasticity such as Terzaghi's stress partitioning principle and Biot's equations for wave propagation. In particular, the variational treatment permits the derivation of a general medium-independent stress partitioning law, and the proposed variational theory predicts that the external stress, the fluid pressure, and the...

Development and application of a fully implicit fluid dynamics code for multiphase flow

International Nuclear Information System (INIS)

Morii, Tadashi; Ogawa, Yumi

1996-01-01

Multiphase flow frequently occurs in a progression of accidents of nuclear reactor severe core damage. The CHAMPAGNE code has been developed to analyze thermohydraulic behavior of multiphase and multicomponent fluid, which requires for its characterization more than one set of velocities, temperatures, masses per unit volume, and so forth at each location in the calculation domain. Calculations of multiphase flow often show physical and numerical instability. The effect of numerical stabilization obtained by the upwind differencing and the fully implicit techniques gives one a convergent solution more easily than other techniques. Several results calculated by the CHAMPAGNE code are explained

The experimental study on bowel ischemia in closed loop obstruction by using multi-phase spiral CT

International Nuclear Information System (INIS)

Zhang Xiaoming; Yang Hanfeng; Huang Xiaohua; Tang Xianying; Jian Pu; Yang Zhengwei; Zhou Jiyong; Zhao Zongwen

2005-01-01

Objective: To evaluate the bowel ischemia in experimental closed loop obstruction by using multi-phase spiral CT. Methods: Twenty-four New Zealand rabbits of both sexes (mean age, 4 months, and mean body weight, 2.5-3.0 kg) were divided randomly into three groups with each group containing 8 rabbits. After clamping 10-15 cm segments of small bowel and their veins for 0.5 hours (Group A), 1-2 hours (Group B), and 3-5 hours (Group C), respectively, multi-phase spiral CT was performed at baseline, and at arterial, venous, and delayed phases after intravenous contrast administration. Then the rabbits were sacrificed to observe their surgical and histological changes. Two radiologists, blinded to the animal model classification and their histological results, individually reviewed the CT images to observe the CT appearances of the closed loop. Statistical significance criteria was determined by P 0.05) at baseline, however, they were significantly different (P<0.05) at all phases after enhancement. Among rabbits without necrotic closed loop, 11 of 13 had continuous enhancement at all phases, while only 1 of 11 rabbits with necrotic closed loop showed continuous enhancement (P<0.05). Conclusion: The ischemia of bowel wall in different phases after clamping small bowel and their veins can be evaluated by using enhanced multi-phase spiral CT. Continuous enhancement of bowel wall in multi-phase spiral CT can be seen prominently in the early bowel ischemia, but necrotic bowel shows no enhancement. (authors)

Modelling multi-phase liquid-sediment scour and resuspension induced by rapid flows using Smoothed Particle Hydrodynamics (SPH) accelerated with a Graphics Processing Unit (GPU)

Science.gov (United States)

Fourtakas, G.; Rogers, B. D.

2016-06-01

A two-phase numerical model using Smoothed Particle Hydrodynamics (SPH) is applied to two-phase liquid-sediments flows. The absence of a mesh in SPH is ideal for interfacial and highly non-linear flows with changing fragmentation of the interface, mixing and resuspension. The rheology of sediment induced under rapid flows undergoes several states which are only partially described by previous research in SPH. This paper attempts to bridge the gap between the geotechnics, non-Newtonian and Newtonian flows by proposing a model that combines the yielding, shear and suspension layer which are needed to predict accurately the global erosion phenomena, from a hydrodynamics prospective. The numerical SPH scheme is based on the explicit treatment of both phases using Newtonian and the non-Newtonian Bingham-type Herschel-Bulkley-Papanastasiou constitutive model. This is supplemented by the Drucker-Prager yield criterion to predict the onset of yielding of the sediment surface and a concentration suspension model. The multi-phase model has been compared with experimental and 2-D reference numerical models for scour following a dry-bed dam break yielding satisfactory results and improvements over well-known SPH multi-phase models. With 3-D simulations requiring a large number of particles, the code is accelerated with a graphics processing unit (GPU) in the open-source DualSPHysics code. The implementation and optimisation of the code achieved a speed up of x58 over an optimised single thread serial code. A 3-D dam break over a non-cohesive erodible bed simulation with over 4 million particles yields close agreement with experimental scour and water surface profiles.

On the inclusion of the interfacial area between phases in the physical and mathematical description of subsurface multiphase flow. 1998 annual progress report

International Nuclear Information System (INIS)

Gray, W.G.; Soll, W.E.; Tompson, A.

1998-01-01

'Improved capabilities for modeling multiphase flow in the subsurface requires that several aspects of the system which impact the flow and transport processes be more properly accounted for. A distinguishing feature of multiphase flow in comparison to single phase flow is the existence of interfaces between fluids. At the microscopic (pore) scale, these interfaces are known to influence system behavior by supporting non-zero stresses such that the pressures in adjacent phases are not equal. In problems of interphase transport at the macroscopic (core) scale, knowledge of the total amount of interfacial area in the system provides a clue to the effectiveness of the communication between phases. Although interfacial processes are central to multiphase flow physics, their treatment in traditional porous-media theories has been implicit rather than explicit; and no attempts have been made to systematically account for the evolution of the interfacial area in dynamic systems or to include the dependence of constitutive functions, such as capillary pressure, on the interfacial area. This project implements a three-pronged approach to assessing the importance of various features of multiphase flow to its description. The research contributes to the improved understanding and precise physical description of multiphase subsurface flow by combining: (1) theoretical derivation of equations, (2) lattice Boltzmann modeling of hydrodynamics to identify characteristics and parameters, and (3) solution of the field-scale equations using a discrete numerical method to assess the advantages and disadvantages of the complete theory. This approach includes both fundamental scientific inquiry and a path for inclusion of the scientific results obtained in a technical tool that will improve assessment capabilities for multiphase flow situations that have arisen due to the introduction of organic materials in the natural environment. This report summarizes work after 1.5 years of a 3

Sensitivity and Uncertainty Analysis of Coupled Reactor Physics Problems : Method Development for Multi-Physics in Reactors

NARCIS (Netherlands)

Perkó, Z.

2015-01-01

This thesis presents novel adjoint and spectral methods for the sensitivity and uncertainty (S&U) analysis of multi-physics problems encountered in the field of reactor physics. The first part focuses on the steady state of reactors and extends the adjoint sensitivity analysis methods well

Complementary Constrains on Component based Multiphase Flow Problems, Should It Be Implemented Locally or Globally?

Science.gov (United States)

Shao, H.; Huang, Y.; Kolditz, O.

2015-12-01

Multiphase flow problems are numerically difficult to solve, as it often contains nonlinear Phase transition phenomena A conventional technique is to introduce the complementarity constraints where fluid properties such as liquid saturations are confined within a physically reasonable range. Based on such constraints, the mathematical model can be reformulated into a system of nonlinear partial differential equations coupled with variational inequalities. They can be then numerically handled by optimization algorithms. In this work, two different approaches utilizing the complementarity constraints based on persistent primary variables formulation[4] are implemented and investigated. The first approach proposed by Marchand et.al[1] is using "local complementary constraints", i.e. coupling the constraints with the local constitutive equations. The second approach[2],[3] , namely the "global complementary constrains", applies the constraints globally with the mass conservation equation. We will discuss how these two approaches are applied to solve non-isothermal componential multiphase flow problem with the phase change phenomenon. Several benchmarks will be presented for investigating the overall numerical performance of different approaches. The advantages and disadvantages of different models will also be concluded. References[1] E.Marchand, T.Mueller and P.Knabner. Fully coupled generalized hybrid-mixed finite element approximation of two-phase two-component flow in porous media. Part I: formulation and properties of the mathematical model, Computational Geosciences 17(2): 431-442, (2013). [2] A. Lauser, C. Hager, R. Helmig, B. Wohlmuth. A new approach for phase transitions in miscible multi-phase flow in porous media. Water Resour., 34,(2011), 957-966. [3] J. Jaffré, and A. Sboui. Henry's Law and Gas Phase Disappearance. Transp. Porous Media. 82, (2010), 521-526. [4] A. Bourgeat, M. Jurak and F. Smaï. Two-phase partially miscible flow and transport modeling in

High-Voltage, Multiphasic, Nanosecond Pulses to Modulate Cellular Responses.

Science.gov (United States)

Ryan, Hollie A; Hirakawa, Shinji; Yang, Enbo; Zhou, Chunrong; Xiao, Shu

2018-04-01

Nanosecond electric pulses are an effective power source in plasma medicine and biological stimulation, in which biophysical responses are governed by peak power and not energy. While uniphasic nanosecond pulse generators are widely available, the recent discovery that biological effects can be uniquely modulated by reversing the polarity of nanosecond duration pulses calls for the development of a multimodal pulse generator. This paper describes a method to generate nanosecond multiphasic pulses for biomedical use, and specifically demonstrates its ability to cancel or enhance cell swelling and blebbing. The generator consists of a series of the fundamental module, which includes a capacitor and a MOSFET switch. A positive or a negative phase pulse module can be produced based on how the switch is connected. Stacking the modules in series can increase the voltage up to 5 kV. Multiple stacks in parallel can create multiphase outputs. As each stack is independently controlled and charged, multiphasic pulses can be created to produce flexible and versatile pulse waveforms. The circuit topology can be used for high-frequency uniphasic or biphasic nanosecond burst pulse production, creating numerous opportunities for the generator in electroporation applications, tissue ablation, wound healing, and nonthermal plasma generation.

Recent developments in biocatalysis in multiphasic ionic liquid reaction systems.

Science.gov (United States)

Meyer, Lars-Erik; von Langermann, Jan; Kragl, Udo

2018-06-01

Ionic liquids are well known and frequently used 'designer solvents' for biocatalytic reactions. This review highlights recent achievements in the field of multiphasic ionic liquid-based reaction concepts. It covers classical biphasic systems including supported ionic liquid phases, thermo-regulated multi-component solvent systems (TMS) and polymerized ionic liquids. These powerful concepts combine unique reaction conditions with a high potential for future applications on a laboratory and industrial scale. The presence of a multiphasic system simplifies downstream processing due to the distribution of the catalyst and reactants in different phases.

Visualization of multiphase flow by neutron radiography

International Nuclear Information System (INIS)

Mishima, Kaichiro; Takenaka, Nobuyuki.

1991-01-01

Neutron radiography (NRG) is a technique which produces images of the internal structure of a body, making use of the attenuation characteristics of neutrons in the materials being observed. Recently, attempts have been made to expand the application of this technique not only to non-destructive testing but also to a variety of industrial and basic research fields. The attenuation of neutrons is large in a light material like water and small in ordinary metals, which difference may make it possible to visualize a multiphase flow in a metallic container. Particularly, the neutron television, which is one of the applied techniques of NRG, is expected to be a useful tool for observing the behavior of two-phase flow, since it produces images in real time. In this paper the basic idea and the method of NRG are presented along with examples of visualization of multiphase flow by NRG. (author)

Parametric Study on the Characteristics of Multiphase Laminar Flow with Density Difference in Various Microchannels

International Nuclear Information System (INIS)

Paek, Seung Ho; Kim, Dong Sung; Choi, Young Ki

2009-01-01

In this paper, we have performed a parametric study on the characteristics of multiphase laminar flow with density difference in various microchannels. The interface between multiphase fluids is rotated by the gravitational forces induced by density difference. The numerical simulations were carried out via commercial CFD package to study the characteristics of multiphase laminar flow. The results of the numerical simulations in this study were verified by comparing with the previously reported experimental results in the literature. We have also proposed a new dimensionless relationship between dimensionless rotation angle of interface and dimensionless parameters are proposed for square microchannels with various aspect ratios. The dimensionless relationship could be widely applied to the reliable design of various microfluidic devices dealing with multiphase laminar flow

Dynamics of multiphase systems with complex microstructure. I. Development of the governing equations through nonequilibrium thermodynamics

NARCIS (Netherlands)

Sagis, L.M.C.; Öttinger, H.C.

2013-01-01

In this paper we present a general model for the dynamic behavior of multiphase systems in which the bulk phases and interfaces have a complex microstructure (for example, immiscible polymer blends with added compatibilizers, or polymer stabilized emulsions with thickening agents dispersed in the

Design of a Modular Monolithic Implicit Solver for Multi-Physics Applications

Science.gov (United States)

Carton De Wiart, Corentin; Diosady, Laslo T.; Garai, Anirban; Burgess, Nicholas; Blonigan, Patrick; Ekelschot, Dirk; Murman, Scott M.

2018-01-01

The design of a modular multi-physics high-order space-time finite-element framework is presented together with its extension to allow monolithic coupling of different physics. One of the main objectives of the framework is to perform efficient high- fidelity simulations of capsule/parachute systems. This problem requires simulating multiple physics including, but not limited to, the compressible Navier-Stokes equations, the dynamics of a moving body with mesh deformations and adaptation, the linear shell equations, non-re effective boundary conditions and wall modeling. The solver is based on high-order space-time - finite element methods. Continuous, discontinuous and C1-discontinuous Galerkin methods are implemented, allowing one to discretize various physical models. Tangent and adjoint sensitivity analysis are also targeted in order to conduct gradient-based optimization, error estimation, mesh adaptation, and flow control, adding another layer of complexity to the framework. The decisions made to tackle these challenges are presented. The discussion focuses first on the "single-physics" solver and later on its extension to the monolithic coupling of different physics. The implementation of different physics modules, relevant to the capsule/parachute system, are also presented. Finally, examples of coupled computations are presented, paving the way to the simulation of the full capsule/parachute system.

Multiphase pumping: indoor performance test and oilfield application

Science.gov (United States)

Kong, Xiangling; Zhu, Hongwu; Zhang, Shousen; Li, Jifeng

2010-03-01

Multiphase pumping is essentially a means of adding energy to the unprocessed effluent which enables the liquid and gas mixture to be transported over a long distances without prior separation. A reduction, consolidation, or elimination of the production infrastructure, such as separation equipments and offshore platforms can be developed more economically. Also it successfully lowed the backpressure of wells, revived dead wells and improved the production and efficiency of oilfield. This paper reviews the issues related to indoor performance test and an oilfield application of the helico-axial multiphase pump designed by China University of Petroleum (Beijing). Pump specification and its hydraulic design are given. Results of performance testing under different condition, such as operational speed and gas volume fraction (GVF) etc are presented. Experimental studies on combination of theoretical analysis showed the multiphase pump satisfies the similitude rule, which can be used in the development of new MPP design and performance prediction. Test results showed that rising the rotation speed and suction pressure could better its performance, pressure boost improved, high efficiency zone expanding and the flow rate related to the optimum working condition increased. The pump worked unstable as GVF increased to a certain extent and slip occurred between two phases in the pump, creating surging and gas lock at a high GVF. A case of application in Nanyang oilfield is also studied.

Modeling of pulsating heat pipes.

Energy Technology Data Exchange (ETDEWEB)

Givler, Richard C.; Martinez, Mario J.

2009-08-01

This report summarizes the results of a computer model that describes the behavior of pulsating heat pipes (PHP). The purpose of the project was to develop a highly efficient (as compared to the heat transfer capability of solid copper) thermal groundplane (TGP) using silicon carbide (SiC) as the substrate material and water as the working fluid. The objective of this project is to develop a multi-physics model for this complex phenomenon to assist with an understanding of how PHPs operate and to be able to understand how various parameters (geometry, fill ratio, materials, working fluid, etc.) affect its performance. The physical processes describing a PHP are highly coupled. Understanding its operation is further complicated by the non-equilibrium nature of the interplay between evaporation/condensation, bubble growth and collapse or coalescence, and the coupled response of the multiphase fluid dynamics among the different channels. A comprehensive theory of operation and design tools for PHPs is still an unrealized task. In the following we first analyze, in some detail, a simple model that has been proposed to describe PHP behavior. Although it includes fundamental features of a PHP, it also makes some assumptions to keep the model tractable. In an effort to improve on current modeling practice, we constructed a model for a PHP using some unique features available in FLOW-3D, version 9.2-3 (Flow Science, 2007). We believe that this flow modeling software retains more of the salient features of a PHP and thus, provides a closer representation of its behavior.

Coupling biomechanics to a cellular level model: an approach to patient-specific image driven multi-scale and multi-physics tumor simulation.

Science.gov (United States)

May, Christian P; Kolokotroni, Eleni; Stamatakos, Georgios S; Büchler, Philippe

2011-10-01

Modeling of tumor growth has been performed according to various approaches addressing different biocomplexity levels and spatiotemporal scales. Mathematical treatments range from partial differential equation based diffusion models to rule-based cellular level simulators, aiming at both improving our quantitative understanding of the underlying biological processes and, in the mid- and long term, constructing reliable multi-scale predictive platforms to support patient-individualized treatment planning and optimization. The aim of this paper is to establish a multi-scale and multi-physics approach to tumor modeling taking into account both the cellular and the macroscopic mechanical level. Therefore, an already developed biomodel of clinical tumor growth and response to treatment is self-consistently coupled with a biomechanical model. Results are presented for the free growth case of the imageable component of an initially point-like glioblastoma multiforme tumor. The composite model leads to significant tumor shape corrections that are achieved through the utilization of environmental pressure information and the application of biomechanical principles. Using the ratio of smallest to largest moment of inertia of the tumor material to quantify the effect of our coupled approach, we have found a tumor shape correction of 20% by coupling biomechanics to the cellular simulator as compared to a cellular simulation without preferred growth directions. We conclude that the integration of the two models provides additional morphological insight into realistic tumor growth behavior. Therefore, it might be used for the development of an advanced oncosimulator focusing on tumor types for which morphology plays an important role in surgical and/or radio-therapeutic treatment planning. Copyright © 2011 Elsevier Ltd. All rights reserved.

RAND-Based Formulations for Isothermal Multiphase Flash

DEFF Research Database (Denmark)

Paterson, Duncan; Michelsen, Michael L.; Stenby, Erling H.

2018-01-01

Two algorithms are proposed for isothermal multiphase flash. These are referred to as modified RAND and vol-RAND. The former uses the chemical potentials and molar-phase amounts as the iteration variables, while the latter uses chemical potentials and phase volumes to cosolve a pressure...

Experimental and Computational Study of Multiphase Flow Hydrodynamics in 2D Trickle Bed Reactors

Science.gov (United States)

Nadeem, H.; Ben Salem, I.; Kurnia, J. C.; Rabbani, S.; Shamim, T.; Sassi, M.

2014-12-01

Trickle bed reactors are largely used in the refining processes. Co-current heavy oil and hydrogen gas flow downward on catalytic particle bed. Fine particles in the heavy oil and/or soot formed by the exothermic catalytic reactions deposit on the bed and clog the flow channels. This work is funded by the refining company of Abu Dhabi and aims at mitigating pressure buildup due to fine deposition in the TBR. In this work, we focus on meso-scale experimental and computational investigations of the interplay between flow regimes and the various parameters that affect them. A 2D experimental apparatus has been built to investigate the flow regimes with an average pore diameter close to the values encountered in trickle beds. A parametric study is done for the development of flow regimes and the transition between them when the geometry and arrangement of the particles within the porous medium are varied. Liquid and gas flow velocities have also been varied to capture the different flow regimes. Real time images of the multiphase flow are captured using a high speed camera, which were then used to characterize the transition between the different flow regimes. A diffused light source was used behind the 2D Trickle Bed Reactor to enhance visualizations. Experimental data shows very good agreement with the published literature. The computational study focuses on the hydrodynamics of multiphase flow and to identify the flow regime developed inside TBRs using the ANSYS Fluent Software package. Multiphase flow inside TBRs is investigated using the "discrete particle" approach together with Volume of Fluid (VoF) multiphase flow modeling. The effect of the bed particle diameter, spacing, and arrangement are presented that may be used to provide guidelines for designing trickle bed reactors.

Multi-Physics Simulation of TREAT Kinetics using MAMMOTH

Energy Technology Data Exchange (ETDEWEB)

DeHart, Mark; Gleicher, Frederick; Ortensi, Javier; Alberti, Anthony; Palmer, Todd

2015-11-01

With the advent of next generation reactor systems and new fuel designs, the U.S. Department of Energy (DOE) has identified the need for the resumption of transient testing of nuclear fuels. DOE has decided that the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory (INL) is best suited for future testing. TREAT is a thermal neutron spectrum nuclear test facility that is designed to test nuclear fuels in transient scenarios. These specific fuels transient tests range from simple temperature transients to full fuel melt accidents. The current TREAT core is driven by highly enriched uranium (HEU) dispersed in a graphite matrix (1:10000 U-235/C atom ratio). At the center of the core, fuel is removed allowing for the insertion of an experimental test vehicle. TREAT’s design provides experimental flexibility and inherent safety during neutron pulsing. This safety stems from the graphite in the driver fuel having a strong negative temperature coefficient of reactivity resulting from a thermal Maxwellian shift with increased leakage, as well as graphite acting as a temperature sink. Air cooling is available, but is generally used post-transient for heat removal. DOE and INL have expressed a desire to develop a simulation capability that will accurately model the experiments before they are irradiated at the facility, with an emphasis on effective and safe operation while minimizing experimental time and cost. At INL, the Multi-physics Object Oriented Simulation Environment (MOOSE) has been selected as the model development framework for this work. This paper describes the results of preliminary simulations of a TREAT fuel element under transient conditions using the MOOSE-based MAMMOTH reactor physics tool.

Hybrid Multiphase CFD Solver for Coupled Dispersed/Segregated Flows in Liquid-Liquid Extraction

Directory of Open Access Journals (Sweden)

Kent E. Wardle

2013-01-01

Full Text Available The flows in stage-wise liquid-liquid extraction devices include both phase segregated and dispersed flow regimes. As a additional layer of complexity, for extraction equipment such as the annular centrifugal contactor, free-surface flows also play a critical role in both the mixing and separation regions of the device and cannot be neglected. Traditionally, computional fluid dynamics (CFD of multiphase systems is regime dependent—different methods are used for segregated and dispersed flows. A hybrid multiphase method based on the combination of an Eulerian multifluid solution framework (per-phase momentum equations and sharp interface capturing using Volume of Fluid (VOF on selected phase pairs has been developed using the open-source CFD toolkit OpenFOAM. Demonstration of the solver capability is presented through various examples relevant to liquid-liquid extraction device flows including three-phase, liquid-liquid-air simulations in which a sharp interface is maintained between each liquid and air, but dispersed phase modeling is used for the liquid-liquid interactions.

Fourier Collocation Approach With Mesh Refinement Method for Simulating Transit-Time Ultrasonic Flowmeters Under Multiphase Flow Conditions.

Science.gov (United States)

Simurda, Matej; Duggen, Lars; Basse, Nils T; Lassen, Benny

2018-02-01

A numerical model for transit-time ultrasonic flowmeters operating under multiphase flow conditions previously presented by us is extended by mesh refinement and grid point redistribution. The method solves modified first-order stress-velocity equations of elastodynamics with additional terms to account for the effect of the background flow. Spatial derivatives are calculated by a Fourier collocation scheme allowing the use of the fast Fourier transform, while the time integration is realized by the explicit third-order Runge-Kutta finite-difference scheme. The method is compared against analytical solutions and experimental measurements to verify the benefit of using mapped grids. Additionally, a study of clamp-on and in-line ultrasonic flowmeters operating under multiphase flow conditions is carried out.

Acceleration methods for multi-physics compressible flow

Science.gov (United States)

Peles, Oren; Turkel, Eli

2018-04-01

In this work we investigate the Runge-Kutta (RK)/Implicit smoother scheme as a convergence accelerator for complex multi-physics flow problems including turbulent, reactive and also two-phase flows. The flows considered are subsonic, transonic and supersonic flows in complex geometries, and also can be either steady or unsteady flows. All of these problems are considered to be a very stiff. We then introduce an acceleration method for the compressible Navier-Stokes equations. We start with the multigrid method for pure subsonic flow, including reactive flows. We then add the Rossow-Swanson-Turkel RK/Implicit smoother that enables performing all these complex flow simulations with a reasonable CFL number. We next discuss the RK/Implicit smoother for time dependent problem and also for low Mach numbers. The preconditioner includes an intrinsic low Mach number treatment inside the smoother operator. We also develop a modified Roe scheme with a corresponding flux Jacobian matrix. We then give the extension of the method for real gas and reactive flow. Reactive flows are governed by a system of inhomogeneous Navier-Stokes equations with very stiff source terms. The extension of the RK/Implicit smoother requires an approximation of the source term Jacobian. The properties of the Jacobian are very important for the stability of the method. We discuss what the chemical physics theory of chemical kinetics tells about the mathematical properties of the Jacobian matrix. We focus on the implication of the Le-Chatelier's principle on the sign of the diagonal entries of the Jacobian. We present the implementation of the method for turbulent flow. We use a two RANS turbulent model - one equation model - Spalart-Allmaras and a two-equation model - k-ω SST model. The last extension is for two-phase flows with a gas as a main phase and Eulerian representation of a dispersed particles phase (EDP). We present some examples for such flow computations inside a ballistic evaluation

Multiscale Multiphysics Developments for Accident Tolerant Fuel Concepts

International Nuclear Information System (INIS)

Gamble, K. A.; Hales, J. D.; Yu, J.; Zhang, Y.; Bai, X.; Andersson, D.; Patra, A.; Wen, W.; Tome, C.; Baskes, M.; Martinez, E.; Stanek, C. R.; Miao, Y.; Ye, B.; Hofman, G. L.; Yacout, A. M.; Liu, W.

2015-01-01

U 3 Si 2 and iron-chromium-aluminum (Fe-Cr-Al) alloys are two of many proposed accident-tolerant fuel concepts for the fuel and cladding, respectively. The behavior of these materials under normal operating and accident reactor conditions is not well known. As part of the Department of Energy's Accident Tolerant Fuel High Impact Problem program significant work has been conducted to investigate the U 3 Si 2 and FeCrAl behavior under reactor conditions. This report presents the multiscale and multiphysics effort completed in fiscal year 2015. The report is split into four major categories including Density Functional Theory Developments, Molecular Dynamics Developments, Mesoscale Developments, and Engineering Scale Developments. The work shown here is a compilation of a collaborative effort between Idaho National Laboratory, Los Alamos National Laboratory, Argonne National Laboratory and Anatech Corp.

Integrated approach for fusion multi-physics coupled analyses based on hybrid CAD and mesh geometries

Energy Technology Data Exchange (ETDEWEB)

Qiu, Yuefeng, E-mail: yuefeng.qiu@kit.edu; Lu, Lei; Fischer, Ulrich

2015-10-15

Highlights: • Integrated approach for neutronics, thermal and structural analyses was developed. • MCNP5/6, TRIPOLI-4 were coupled with CFX, Fluent and ANSYS Workbench. • A novel meshing approach has been proposed for describing MC geometry. - Abstract: Coupled multi-physics analyses on fusion reactor devices require high-fidelity neutronic models, and flexible, accurate data exchanging between various calculation codes. An integrated coupling approach has been developed to enable the conversion of CAD, mesh, or hybrid geometries for Monte Carlo (MC) codes MCNP5/6, TRIPOLI-4, and translation of nuclear heating data for CFD codes Fluent, CFX and structural mechanical software ANSYS Workbench. The coupling approach has been implemented based on SALOME platform with CAD modeling, mesh generation and data visualization capabilities. A novel meshing approach has been developed for generating suitable meshes for MC geometry descriptions. The coupling approach has been concluded to be reliable and efficient after verification calculations of several application cases.

Multiphase flow in porous media using CFD

DEFF Research Database (Denmark)

Hemmingsen, Casper Schytte; Walther, Jens Honore

. This approach is widely used for single phase flow, but not for multiphase flow in porous media. This might be due to the complexity of introducing relative permeability and capillary pressure in the CFD solver.The introduction of relative permeability and capillary pressure may cause numerical instabilities...

Dynamic Data-Driven Reduced-Order Models of Macroscale Quantities for the Prediction of Equilibrium System State for Multiphase Porous Medium Systems

Science.gov (United States)

Talbot, C.; McClure, J. E.; Armstrong, R. T.; Mostaghimi, P.; Hu, Y.; Miller, C. T.

2017-12-01

Microscale simulation of multiphase flow in realistic, highly-resolved porous medium systems of a sufficient size to support macroscale evaluation is computationally demanding. Such approaches can, however, reveal the dynamic, steady, and equilibrium states of a system. We evaluate methods to utilize dynamic data to reduce the cost associated with modeling a steady or equilibrium state. We construct data-driven models using extensions to dynamic mode decomposition (DMD) and its connections to Koopman Operator Theory. DMD and its variants comprise a class of equation-free methods for dimensionality reduction of time-dependent nonlinear dynamical systems. DMD furnishes an explicit reduced representation of system states in terms of spatiotemporally varying modes with time-dependent oscillation frequencies and amplitudes. We use DMD to predict the steady and equilibrium macroscale state of a realistic two-fluid porous medium system imaged using micro-computed tomography (µCT) and simulated using the lattice Boltzmann method (LBM). We apply Koopman DMD to direct numerical simulation data resulting from simulations of multiphase fluid flow through a 1440x1440x4320 section of a full 1600x1600x5280 realization of imaged sandstone. We determine a representative set of system observables via dimensionality reduction techniques including linear and kernel principal component analysis. We demonstrate how this subset of macroscale quantities furnishes a representation of the time-evolution of the system in terms of dynamic modes, and discuss the selection of a subset of DMD modes yielding the optimal reduced model, as well as the time-dependence of the error in the predicted equilibrium value of each macroscale quantity. Finally, we describe how the above procedure, modified to incorporate methods from compressed sensing and random projection techniques, may be used in an online fashion to facilitate adaptive time-stepping and parsimonious storage of system states over time.

Development of FAST.Farm: A New Multiphysics Engineering Tool for Wind-Farm Design and Analysis

Energy Technology Data Exchange (ETDEWEB)

Jonkman, Jason; Annoni, Jennifer; Hayman, Greg; Jonkman, Bonnie; Purkayastha, Avi

2017-01-09

This paper presents the development of FAST.Farm, a new multiphysics tool applicable to engineering problems in research and industry involving wind farm performance and cost optimization that is needed to address the current underperformance, failures, and expenses plaguing the wind industry. Achieving wind cost-of-energy targets - which requires improvements in wind farm performance and reliability, together with reduced uncertainty and expenditures - has been eluded by the complicated nature of the wind farm design problem, especially the sophisticated interaction between atmospheric phenomena and wake dynamics and array effects. FAST.Farm aims to balance the need for accurate modeling of the relevant physics for predicting power performance and loads while maintaining low computational cost to support a highly iterative and probabilistic design process and system-wide optimization. FAST.Farm makes use of FAST to model the aero-hydro-servo-elastics of distinct turbines in the wind farm, and it is based on some of the principles of the Dynamic Wake Meandering (DWM) model, but avoids many of the limitations of existing DWM implementations.

Enhancement pattern of small hepatic hemangioma: findings on multiphase spiral CT and dynamic MRI

International Nuclear Information System (INIS)

Choi, Byung In; Lee, Seung Koo; Kim, Myeong Jin; Chung, Jae Joon; Yoo, Hyung Sik; Lee, Jong Tae

1999-01-01

To compare the enhancement characteristics of small hemangiomas seen on multiphase spiral CT and dynamic MR imaging. Thirteen patients with 20 hepatic hemangiomas less than 25mm in diameter underwent both multiphase spiral CT and dynamic MR imaging. All lesions were assigned to one of three classified into 3 categories according to the enhancement pattern seen on multiphase spiral CT : typical delayed pooling, atypical early enhancement, or continuous low attenuation. The enhancement patterns seen on spiral CT and on dynamic MRI were correlated. On CT scans, ten lesions (50%) showed delayed pooling. Six (30%) showed early arterial enhancement and four (20%) showed continuous low attenuation. On delayed-phase MRI, all lesions showed delayed high signal intensity compared to adjacent liver parenchyma. Four of six lesions with early enhancement on CT showed peripheral globular enhancement on early arterial-phase MRI. On multiphase spiral CT scans, small hemangiomas can show variable atypical enhancement features. In this situation, contrast-enhanced dynamic MRI is helpful for the diagnosis of hemangiomas

Modelling of multiphase flow in concrete cells of the radioactive waste storage facility at El Cabril (Spain)

International Nuclear Information System (INIS)

Chaparro, M.C.; Saaltink, M.W.

2015-01-01

El Cabril is the low and intermediate level radioactive waste disposal facility for Spain. After sealing the cells that stored the radioactive waste, water was collected from a drainpipe, indicating the flow of water within the cell. A hypothesis had been proposed to explain this phenomenon which consists of capillary rise from groundwater and evaporation and condensation within the cell produced by temperature gradients caused by seasonal temperature fluctuations outside. To corroborate this hypothesis a 2D numerical model was made taking into account all relevant processes such as multiphase flow and heat transport. Data were used measured by sensors in the cells and data from laboratory test. There is a good agreement between the temperature measured by the sensors and the ones calculated by the model. The model shows a drying of the concrete at the hot side (that is the wall during summer and the container during winter). The concrete is saturated with water at the cold side (that is the container during summer and the wall in winter), leading to runoff of water to the drainpipe. The flux at this drainpipe occurred in the two yearly periods, being higher in winter than in summer. (authors)

Analysis of Voltage Forming Methods for Multiphase Inverters

Directory of Open Access Journals (Sweden)

Tadas Lipinskis

2013-05-01

Full Text Available The article discusses advantages of the multiphase AC induction motor over three or less phase motors. It presents possible stator winding configurations for a multiphase induction motor. Various fault control strategies were reviewed for phases feeding the motor. The authors propose a method for quality evaluation of voltage forming algorithm in the inverter. Simulation of a six-phase voltage source inverter, voltage in which is formed using a simple SPWM control algorithm, was performed in Matlab Simulink. Simulation results were evaluated using the proposed method. Inverter’s power stage was powered by 400 V DC source. The spectrum of output currents was analysed and the magnitude of the main frequency component was at least 12 times greater than the next biggest-magnitude component. The value of rectified inverter voltage was 373 V.Article in Lithuanian

Multiphase averaging of periodic soliton equations

International Nuclear Information System (INIS)

Forest, M.G.

1979-01-01

The multiphase averaging of periodic soliton equations is considered. Particular attention is given to the periodic sine-Gordon and Korteweg-deVries (KdV) equations. The periodic sine-Gordon equation and its associated inverse spectral theory are analyzed, including a discussion of the spectral representations of exact, N-phase sine-Gordon solutions. The emphasis is on physical characteristics of the periodic waves, with a motivation from the well-known whole-line solitons. A canonical Hamiltonian approach for the modulational theory of N-phase waves is prescribed. A concrete illustration of this averaging method is provided with the periodic sine-Gordon equation; explicit averaging results are given only for the N = 1 case, laying a foundation for a more thorough treatment of the general N-phase problem. For the KdV equation, very general results are given for multiphase averaging of the N-phase waves. The single-phase results of Whitham are extended to general N phases, and more importantly, an invariant representation in terms of Abelian differentials on a Riemann surface is provided. Several consequences of this invariant representation are deduced, including strong evidence for the Hamiltonian structure of N-phase modulational equations

Generating a Multiphase Equation of State with Swarm Intelligence

Science.gov (United States)

Cox, Geoffrey

2017-06-01

Hydrocode calculations require knowledge of the variation of pressure of a material with density and temperature, which is given by the equation of state. An accurate model needs to account for discontinuities in energy, density and properties of a material across a phase boundary. When generating a multiphase equation of state the modeller attempts to balance the agreement between the available data for compression, expansion and phase boundary location. However, this can prove difficult because minor adjustments in the equation of state for a single phase can have a large impact on the overall phase diagram. Recently, Cox and Christie described a method for combining statistical-mechanics-based condensed matter physics models with a stochastic analysis technique called particle swarm optimisation. The models produced show good agreement with experiment over a wide range of pressure-temperature space. This talk details the general implementation of this technique, shows example results, and describes the types of analysis that can be performed with this method.

Grain scale simulation of multiphase flow through porous media; Simulacao em escala granular do escoamento multifasico em meio poroso

Energy Technology Data Exchange (ETDEWEB)

Domingos, Ricardo Golghetto; Cheng, Liang-Yee [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica

2012-07-01

Since the grain scale modeling of multi-phase flow in porous media is of great interest for the oil industry, the aim of the present research is to show an implementation of Moving Particle Semi-Implicit (MPS) method for the grain scale simulation of multi-phase flow in porous media. Geometry data obtained by a high-resolution CT scan of a sandstone sample has been used as input for the simulations. The results of the simulations performed considering different resolutions are given, the head loss and permeability obtained numerically, as well as the influence of the wettability of the fluids inside the sample of the reservoir's sandstone. (author)

Induction Heating Process Design Using COMSOL Multiphysics Software

Directory of Open Access Journals (Sweden)

Andy Triwinarko

2011-08-01

Full Text Available Induction heating is clean environmental heating process due to a non-contact heating process. There is lots of the induction heating type that be used in the home appliance but it is still new technology in Indonesia. The main interesting area of the induction heating design is the efficiency of the usage of energy and choice of the plate material. COMSOL Multiphysics Software can be used to simulate and estimate the induction heating process. Therefore, the software can be used to design the induction heating process that will have a optimum efficiency. The properties of the induction heating design were also simulated and analyzed such as effect of inductors width, inductors distance, and conductive plate material. The result was shown that the good design of induction heating must have a short width and distance inductor and used silicon carbide as material plate with high frequency controller.

Development of a three dimension multi-physics code for molten salt fast reactor

International Nuclear Information System (INIS)

Cheng Maosong; Dai Zhimin

2014-01-01

Molten Salt Reactor (MSR) was selected as one of the six innovative nuclear reactors by the Generation IV International Forum (GIF). The circulating-fuel in the can-type molten salt fast reactor makes the neutronics and thermo-hydraulics of the reactor strongly coupled and different from that of traditional solid-fuel reactors. In the present paper: a new coupling model is presented that physically describes the inherent relations between the neutron flux, the delayed neutron precursor, the heat transfer and the turbulent flow. Based on the model, integrating nuclear data processing, CAD modeling, structured and unstructured mesh technology, data analysis and visualization application, a three dimension steady state simulation code system (MSR3DS) for the can-type molten salt fast reactor is developed and validated. In order to demonstrate the ability of the code, the three dimension distributions of the velocity, the neutron flux, the delayed neutron precursor and the temperature were obtained for the simplified MOlten Salt Advanced Reactor Transmuter (MOSART) using this code. The results indicate that the MSR3DS code can provide a feasible description of multi-physical coupling phenomena in can-type molten salt fast reactor. Furthermore, the code can well predict the flow effect of fuel salt and the transport effect of the turbulent diffusion. (authors)

Online recognition of the multiphase flow regime and study of slug flow in pipeline

International Nuclear Information System (INIS)

Guo Liejin; Bai Bofeng; Zhao Liang; Wang Xin; Gu Hanyang

2009-01-01

Multiphase flow is the phenomenon existing widely in nature, daily life, as well as petroleum and chemical engineering industrial fields. The interface structure among multiphase and their movement are complicated, which distribute random and heterogeneously in the spatial and temporal scales and have multivalue of the flow structure and state. Flow regime is defined as the macro feature about the multiphase interface structure and its distribution, which is an important feature to describe multiphase flow. The energy and mass transport mechanism differ much for each flow regimes. It is necessary to solve the flow regime recognition to get a clear understanding of the physical phenomena and their mechanism of multiphase flow. And the flow regime is one of the main factors affecting the online measurement accuracy of phase fraction, flow rate and other phase parameters. Therefore, it is of great scientific and technological importance to develop new principles and methods of multiphase flow regime online recognition, and of great industrial background. In this paper, the key reasons that the present method cannot be used to solve the industrial multiphase flow pattern recognition are clarified firstly. Then the prerequisite to realize the online recognition of multiphase flow regime is analyzed, and the recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of single

Design Process of IDT Aided by Multiphysics FE Analyses

Directory of Open Access Journals (Sweden)

A Martowicz

2016-09-01

Full Text Available Presented work is devoted to a design process performed for the interdigital transducer, which is a perspective application for the area of structural health monitoring. In order to obtain the desirable characteristic of the transducer fully coupled numerical analyses were performed in ANSYS Multiphysics software. Utilised finite element models considered both structural dynamics and properties of used piezoelectric material. The process of design improvement was preceded by the sensitivity analysis. In order to search for the best electrode pattern selected geometrical features of the transducer were assumed to vary within allowed ranges. The design parameters, which were taken into account, related to the efficiency of proposed transducer design for the emission of acoustic waves in the monitored structure. The search objectives considered the criteria related to the shape of the beampattern and amplitudes of generated Lamb waves. As a result of the optimization procedure, the simultaneous increase of anti-symmetric mode amplitude and the reduction of undesirable symmetric mode amplitude of generated Lamb waves in the direction perpendicular to the transducer fingers was expected. Another aim of the optimization was to minimize the main lobe width and undesirable contribution of both symmetric and anti-symmetric waves in the parallel direction to the transducer fingers. The response surface method and genetic algorithms were used for fast and effective search through the input design domain.

Efficiency Improvement of a High Dynamic BLDC Linear Motor by Multiphase Control

OpenAIRE

Lemmens, Joris; Vanvlasselaer, Kris; Mulier, Kristof; Goossens, Stijn; Symens, Wim; Driesen, Johan

2013-01-01

This paper proposes a multiphase control strategy for a high dynamic brushless DC linear motor as an alternative for conventional three-phase field-oriented control. Analysis of the magnetic field waveforms shows that three-phase control is not optimal for the 6-slot 7-pole motor topology. Therefore, a multiphase control strategy is elaborated which injects currents proportional to the electromotive force into each of the nine stator coil groups. This results in a maximal alignment force ...

Laboratory setup and results of experiments on two-dimensional multiphase flow in porous media

International Nuclear Information System (INIS)

McBride, J.F.; Graham, D.N.

1990-10-01

In the event of an accidental release into earth's subsurface of an immiscible organic liquid, such as a petroleum hydrocarbon or chlorinated organic solvent, the spatial and temporal distribution of the organic liquid is of great interest when considering efforts to prevent groundwater contamination or restore contaminated groundwater. An accurate prediction of immiscible organic liquid migration requires the incorporation of relevant physical principles in models of multiphase flow in porous media; these physical principles must be determined from physical experiments. This report presents a series of such experiments performed during the 1970s at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland. The experiments were designed to study the transient, two-dimensional displacement of three immiscible fluids in a porous medium. This experimental study appears to be the most detailed published to date. The data obtained from these experiments are suitable for the validation and test calibration of multiphase flow codes. 73 refs., 140 figs

Modeling of multi-phase interactions of reactive nitrogen between snow and air in Antarctica

Science.gov (United States)

McCrystall, M.; Chan, H. G. V.; Frey, M. M.; King, M. D.

2016-12-01

In polar and snow-covered regions, the snowpack is an important link between atmospheric, terrestrial and oceanic systems. Trace gases, including nitrogen oxides, produced via photochemical reactions in snow are partially released to the lower atmosphere with considerable impact on its composition. However, the post-depositional processes that change the chemical composition and physical properties of the snowpack are still poorly understood. Most current snow chemistry models oversimplify as they assume air-liquid interactions and aqueous phase chemistry taking place at the interface between the snow grain and air. Here, we develop a novel temperature dependent multi-phase (gas-liquid-ice) physical exchange model for reactive nitrogen. The model is validated with existing year-round observations of nitrate in the top 0.5-2 cm of snow and the overlying atmosphere at two very different Antarctic locations: Dome C on the East Antarctic Plateau with very low annual mean temperature (-54ºC) and accumulation rate (rate and high background level of sea salt aerosol. We find that below the eutectic temperature of the H2O/dominant ion mixture the surface snow nitrate is controlled by kinetic adsorption onto the surface of snow grains followed by grain diffusion. Above the eutectic temperature, in addition to the former two processes, thermodynamic equilibrium of HNO3 between interstitial air and liquid water pockets, possibly present at triple junctions or grooves at grain boundaries, greatly enhances the nitrate uptake by snow in agreement with the concentration peak observed in summer.

Performance analysis of variable speed multiphase induction motor with pole phase modulation

Directory of Open Access Journals (Sweden)

Liu Huijuan

2016-09-01

Full Text Available The pole phase modulation (PPM technique is an effective method to extend speed range and torque capabilities for an integrated starter and hybrid electric vehicles applications. In this paper, the five pole-phase combination types of a multiphase induction motor (IM with 36 stator slots and 36 stator conductors are presented and compared quantitatively by using the time-stepping finite element method (TS-FEM. The 36 stator conductors of the proposed multiphase IM are fed by a 36 leg inverter and the current phase angle and amplitude of each stator conductor can be controlled independently. This paper focuses on the winding connection, the PPM technique and the performance comparative analysis of each pole-phase combination types of the proposed multiphase IM. The flux distribution, air-gap flux density, output torque, core losses and efficiency of five pole-phase combination types have been investigated.

Poroelastic Modeling as a Proof of Concept for Modular Representation of Coupled Geophysical Processes

Science.gov (United States)

Walker, R. L., II; Knepley, M.; Aminzadeh, F.

2017-12-01

We seek to use the tools provided by the Portable, Extensible Toolkit for Scientific Computation (PETSc) to represent a multiphysics problem in a form that decouples the element definition from the fully coupled equation through the use of pointwise functions that imitate the strong form of the governing equation. This allows allows individual physical processes to be expressed as independent kernels that may be then coupled with the existing finite element framework, PyLith, and capitalizes upon the flexibility offered by the solver, data management, and time stepping algorithms offered by PETSc. To demonstrate a characteristic example of coupled geophysical simulation devised in this manner, we present a model of a synthetic poroelastic environment, with and without the consideration of inertial effects, with fluid initially represented as a single phase. Matrix displacement and fluid pressure serve as the desired unknowns, with the option for various model parameters represented as dependent variables of the central unknowns. While independent of PyLith, this model also serves to showcase the adaptability of physics kernels for synthetic forward modeling. In addition, we seek to expand the base case to demonstrate the impact of modeling fluid as single phase compressible versus a single incompressible phase. As a goal, we also seek to include multiphase fluid modeling, as well as capillary effects.

A relaxation-projection method for compressible flows. Part II: Artificial heat exchanges for multiphase shocks

International Nuclear Information System (INIS)

Petitpas, Fabien; Franquet, Erwin; Saurel, Richard; Le Metayer, Olivier

2007-01-01

The relaxation-projection method developed in Saurel et al. [R. Saurel, E. Franquet, E. Daniel, O. Le Metayer, A relaxation-projection method for compressible flows. Part I: The numerical equation of state for the Euler equations, J. Comput. Phys. (2007) 822-845] is extended to the non-conservative hyperbolic multiphase flow model of Kapila et al. [A.K. Kapila, Menikoff, J.B. Bdzil, S.F. Son, D.S. Stewart, Two-phase modeling of deflagration to detonation transition in granular materials: reduced equations, Physics of Fluids 13(10) (2001) 3002-3024]. This model has the ability to treat multi-temperatures mixtures evolving with a single pressure and velocity and is particularly interesting for the computation of interface problems with compressible materials as well as wave propagation in heterogeneous mixtures. The non-conservative character of this model poses however computational challenges in the presence of shocks. The first issue is related to the Riemann problem resolution that necessitates shock jump conditions. Thanks to the Rankine-Hugoniot relations proposed and validated in Saurel et al. [R. Saurel, O. Le Metayer, J. Massoni, S. Gavrilyuk, Shock jump conditions for multiphase mixtures with stiff mechanical relaxation, Shock Waves 16 (3) (2007) 209-232] exact and approximate 2-shocks Riemann solvers are derived. However, the Riemann solver is only a part of a numerical scheme and non-conservative variables pose extra difficulties for the projection or cell average of the solution. It is shown that conventional Godunov schemes are unable to converge to the exact solution for strong multiphase shocks. This is due to the incorrect partition of the energies or entropies in the cell averaged mixture. To circumvent this difficulty a specific Lagrangian scheme is developed. The correct partition of the energies is achieved by using an artificial heat exchange in the shock layer. With the help of an asymptotic analysis this heat exchange takes a similar form as

A relaxation-projection method for compressible flows. Part II: Artificial heat exchanges for multiphase shocks

Science.gov (United States)

Petitpas, Fabien; Franquet, Erwin; Saurel, Richard; Le Metayer, Olivier

2007-08-01

The relaxation-projection method developed in Saurel et al. [R. Saurel, E. Franquet, E. Daniel, O. Le Metayer, A relaxation-projection method for compressible flows. Part I: The numerical equation of state for the Euler equations, J. Comput. Phys. (2007) 822-845] is extended to the non-conservative hyperbolic multiphase flow model of Kapila et al. [A.K. Kapila, Menikoff, J.B. Bdzil, S.F. Son, D.S. Stewart, Two-phase modeling of deflagration to detonation transition in granular materials: reduced equations, Physics of Fluids 13(10) (2001) 3002-3024]. This model has the ability to treat multi-temperatures mixtures evolving with a single pressure and velocity and is particularly interesting for the computation of interface problems with compressible materials as well as wave propagation in heterogeneous mixtures. The non-conservative character of this model poses however computational challenges in the presence of shocks. The first issue is related to the Riemann problem resolution that necessitates shock jump conditions. Thanks to the Rankine-Hugoniot relations proposed and validated in Saurel et al. [R. Saurel, O. Le Metayer, J. Massoni, S. Gavrilyuk, Shock jump conditions for multiphase mixtures with stiff mechanical relaxation, Shock Waves 16 (3) (2007) 209-232] exact and approximate 2-shocks Riemann solvers are derived. However, the Riemann solver is only a part of a numerical scheme and non-conservative variables pose extra difficulties for the projection or cell average of the solution. It is shown that conventional Godunov schemes are unable to converge to the exact solution for strong multiphase shocks. This is due to the incorrect partition of the energies or entropies in the cell averaged mixture. To circumvent this difficulty a specific Lagrangian scheme is developed. The correct partition of the energies is achieved by using an artificial heat exchange in the shock layer. With the help of an asymptotic analysis this heat exchange takes a similar form as

Multiphase flow modelling of volcanic ash particle settling in water using adaptive unstructured meshes

Science.gov (United States)

Jacobs, C. T.; Collins, G. S.; Piggott, M. D.; Kramer, S. C.; Wilson, C. R. G.

2013-02-01

Small-scale experiments of volcanic ash particle settling in water have demonstrated that ash particles can either settle slowly and individually, or rapidly and collectively as a gravitationally unstable ash-laden plume. This has important implications for the emplacement of tephra deposits on the seabed. Numerical modelling has the potential to extend the results of laboratory experiments to larger scales and explore the conditions under which plumes may form and persist, but many existing models are computationally restricted by the fixed mesh approaches that they employ. In contrast, this paper presents a new multiphase flow model that uses an adaptive unstructured mesh approach. As a simulation progresses, the mesh is optimized to focus numerical resolution in areas important to the dynamics and decrease it where it is not needed, thereby potentially reducing computational requirements. Model verification is performed using the method of manufactured solutions, which shows the correct solution convergence rates. Model validation and application considers 2-D simulations of plume formation in a water tank which replicate published laboratory experiments. The numerically predicted settling velocities for both individual particles and plumes, as well as instability behaviour, agree well with experimental data and observations. Plume settling is clearly hindered by the presence of a salinity gradient, and its influence must therefore be taken into account when considering particles in bodies of saline water. Furthermore, individual particles settle in the laminar flow regime while plume settling is shown (by plume Reynolds numbers greater than unity) to be in the turbulent flow regime, which has a significant impact on entrainment and settling rates. Mesh adaptivity maintains solution accuracy while providing a substantial reduction in computational requirements when compared to the same simulation performed using a fixed mesh, highlighting the benefits of an

Multi-scale multi-physics computational chemistry simulation based on ultra-accelerated quantum chemical molecular dynamics method for structural materials in boiling water reactor

International Nuclear Information System (INIS)

Miyamoto, Akira; Sato, Etsuko; Sato, Ryo; Inaba, Kenji; Hatakeyama, Nozomu

2014-01-01

In collaboration with experimental experts we have reported in the present conference (Hatakeyama, N. et al., “Experiment-integrated multi-scale, multi-physics computational chemistry simulation applied to corrosion behaviour of BWR structural materials”) the results of multi-scale multi-physics computational chemistry simulations applied to the corrosion behaviour of BWR structural materials. In macro-scale, a macroscopic simulator of anode polarization curve was developed to solve the spatially one-dimensional electrochemical equations on the material surface in continuum level in order to understand the corrosion behaviour of typical BWR structural material, SUS304. The experimental anode polarization behaviours of each pure metal were reproduced by fitting all the rates of electrochemical reactions and then the anode polarization curve of SUS304 was calculated by using the same parameters and found to reproduce the experimental behaviour successfully. In meso-scale, a kinetic Monte Carlo (KMC) simulator was applied to an actual-time simulation of the morphological corrosion behaviour under the influence of an applied voltage. In micro-scale, an ultra-accelerated quantum chemical molecular dynamics (UA-QCMD) code was applied to various metallic oxide surfaces of Fe 2 O 3 , Fe 3 O 4 , Cr 2 O 3 modelled as same as water molecules and dissolved metallic ions on the surfaces, then the dissolution and segregation behaviours were successfully simulated dynamically by using UA-QCMD. In this paper we describe details of the multi-scale, multi-physics computational chemistry method especially the UA-QCMD method. This method is approximately 10,000,000 times faster than conventional first-principles molecular dynamics methods based on density-functional theory (DFT), and the accuracy was also validated for various metals and metal oxides compared with DFT results. To assure multi-scale multi-physics computational chemistry simulation based on the UA-QCMD method for

THE WORK SIMULATION OF FLOW RATE FOR CARRIAGES' REPAIR AS A MULTIPHASE, MULTIPLEX AND MULTIDISCIPLINARY SYSTEM OF MASS SERVICE

Directory of Open Access Journals (Sweden)

V. V. Myamlin

2011-04-01

Full Text Available The algorithm of computer simulation of the flexible flow for repair of cars as a multiphase polychannel manyobject queuing system is presented. The basic operators of the model are given and their work is described.

Effect of Finite Particle Size on Convergence of Point Particle Models in Euler-Lagrange Multiphase Dispersed Flow

Science.gov (United States)

Nili, Samaun; Park, Chanyoung; Haftka, Raphael T.; Kim, Nam H.; Balachandar, S.

2017-11-01

Point particle methods are extensively used in simulating Euler-Lagrange multiphase dispersed flow. When particles are much smaller than the Eulerian grid the point particle model is on firm theoretical ground. However, this standard approach of evaluating the gas-particle coupling at the particle center fails to converge as the Eulerian grid is reduced below particle size. We present an approach to model the interaction between particles and fluid for finite size particles that permits convergence. We use the generalized Faxen form to compute the force on a particle and compare the results against traditional point particle method. We apportion the different force components on the particle to fluid cells based on the fraction of particle volume or surface in the cell. The application is to a one-dimensional model of shock propagation through a particle-laden field at moderate volume fraction, where the convergence is achieved for a well-formulated force model and back coupling for finite size particles. Comparison with 3D direct fully resolved numerical simulations will be used to check if the approach also improves accuracy compared to the point particle model. Work supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Multiphase flow parameter estimation based on laser scattering

Science.gov (United States)

Vendruscolo, Tiago P.; Fischer, Robert; Martelli, Cicero; Rodrigues, Rômulo L. P.; Morales, Rigoberto E. M.; da Silva, Marco J.

2015-07-01

The flow of multiple constituents inside a pipe or vessel, known as multiphase flow, is commonly found in many industry branches. The measurement of the individual flow rates in such flow is still a challenge, which usually requires a combination of several sensor types. However, in many applications, especially in industrial process control, it is not necessary to know the absolute flow rate of the respective phases, but rather to continuously monitor flow conditions in order to quickly detect deviations from the desired parameters. Here we show how a simple and low-cost sensor design can achieve this, by using machine-learning techniques to distinguishing the characteristic patterns of oblique laser light scattered at the phase interfaces. The sensor is capable of estimating individual phase fluxes (as well as their changes) in multiphase flows and may be applied to safety applications due to its quick response time.

Multiphase flow parameter estimation based on laser scattering

International Nuclear Information System (INIS)

Vendruscolo, Tiago P; Fischer, Robert; Martelli, Cicero; Da Silva, Marco J; Rodrigues, Rômulo L P; Morales, Rigoberto E M

2015-01-01

The flow of multiple constituents inside a pipe or vessel, known as multiphase flow, is commonly found in many industry branches. The measurement of the individual flow rates in such flow is still a challenge, which usually requires a combination of several sensor types. However, in many applications, especially in industrial process control, it is not necessary to know the absolute flow rate of the respective phases, but rather to continuously monitor flow conditions in order to quickly detect deviations from the desired parameters. Here we show how a simple and low-cost sensor design can achieve this, by using machine-learning techniques to distinguishing the characteristic patterns of oblique laser light scattered at the phase interfaces. The sensor is capable of estimating individual phase fluxes (as well as their changes) in multiphase flows and may be applied to safety applications due to its quick response time. (paper)

Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

Energy Technology Data Exchange (ETDEWEB)

Mecartnery, Martha [Univ. of California, Irvine, CA (United States); Graeve, Olivia [Univ. of California, San Diego, CA (United States); Patel, Maulik [Univ. of Liverpool (United Kingdom)

2017-05-25

The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

International Nuclear Information System (INIS)

Mecartnery, Martha; Graeve, Olivia; Patel, Maulik

2017-01-01

The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

A multiphase series-resonant converter with a new topology and a reduced number of thyristors

NARCIS (Netherlands)

Huisman, H.

1995-01-01

Multiphase series resonant (SR) power converters provide a flexible way to transform power between a utility grid and a multiphase load or source. The current implementations all suffer from a high component count, which makes the use of these power converters unattractive from an economical point

Noninvasive tomographic and velocimetric monitoring of multiphase flows

International Nuclear Information System (INIS)

Chaouki, J.; Dudukovic, M.P.

1997-01-01

A condensed review of recent advances accomplished in the development and the applications of noninvasive tomographic and velocimetric measurement techniques to multiphase flows and systems is presented. In recent years utilization of such noninvasive techniques has become widespread in many engineering disciplines that deal with systems involving two immiscible phases or more. Tomography provides concentration, holdup, or 2D or 3D density distribution of at least one component of the multiphase system, whereas velocimetry provides the dynamic features of the phase of interest such as the flow pattern, the velocity field, the 2D or 3D instantaneous movements, etc. The following review is divided into two parts. The first part summarizes progress and developments in flow imaging techniques using γ-ray and X-ray transmission tomography; X-ray radiography; neutron transmission tomography and radiography; positron emission tomography; X-ray diffraction tomography; nuclear magnetic resonance imaging; electrical capacitance tomography; optical tomography; microwave tomography; and ultrasonic tomography. The second part of the review summarizes progress and developments in the following velocimetry techniques: positron emission particle tracking; radioactive particle tracking; cinematography; laser-Doppler anemometry; particle image velocimetry; and fluorescence particle image velocimetry. The basic principles of tomography and velocimetry techniques are outlined, along with advantages and limitations inherent to each technique. The hydrodynamic and structural information yielded by these techniques is illustrated through a literature survey on their successful applications to the study of multiphase systems in such fields as particulate solids processes, fluidization engineering, porous media, pipe flows, transport within packed beds and sparged reactors, etc

Multi-physic simulations of irradiation experiments in a technological irradiation reactor; Modelisation pluridisciplinaire d'experiences d'irradiation dans un reacteur d'irradiation technologique

Energy Technology Data Exchange (ETDEWEB)

Bonaccorsi, Th

2007-09-15

A Material Testing Reactor (MTR) makes it possible to irradiate material samples under intense neutron and photonic fluxes. These experiments are carried out in experimental devices localised in the reactor core or in periphery (reflector). Available physics simulation tools only treat, most of the time, one physics field in a very precise way. Multi-physic simulations of irradiation experiments therefore require a sequential use of several calculation codes and data exchanges between these codes: this corresponds to problems coupling. In order to facilitate multi-physic simulations, this thesis sets up a data model based on data-processing objects, called Technological Entities. This data model is common to all of the physics fields. It permits defining the geometry of an irradiation device in a parametric way and to associate information about materials to it. Numerical simulations are encapsulated into interfaces providing the ability to call specific functionalities with the same command (to initialize data, to launch calculations, to post-treat, to get results,... ). Thus, once encapsulated, numerical simulations can be re-used for various studies. This data model is developed in a SALOME platform component. The first application case made it possible to perform neutronic simulations (OSIRIS reactor and RJH) coupled with fuel behavior simulations. In a next step, thermal hydraulics could also be taken into account. In addition to the improvement of the calculation accuracy due to the physical phenomena coupling, the time spent in the development phase of the simulation is largely reduced and the possibilities of uncertainty treatment are under consideration. (author)

Development of FAST.Farm: A New Multiphysics Engineering Tool for Wind Farm Design and Analysis: Preprint

Energy Technology Data Exchange (ETDEWEB)

Jonkman, Jason; Annoni, Jennifer; Hayman, Greg; Jonkman, Bonnie; Purkayastha, Avi

2017-01-01

This paper presents the development of FAST.Farm, a new multiphysics tool applicable to engineering problems in research and industry involving wind farm performance and cost optimization that is needed to address the current underperformance, failures, and expenses plaguing the wind industry. Achieving wind cost-of-energy targets - which requires improvements in wind farm performance and reliability, together with reduced uncertainty and expenditures - has been eluded by the complicated nature of the wind farm design problem, especially the sophisticated interaction between atmospheric phenomena and wake dynamics and array effects. FAST.Farm aims to balance the need for accurate modeling of the relevant physics for predicting power performance and loads while maintaining low computational cost to support a highly iterative and probabilistic design process and system-wide optimization. FAST.Farm makes use of FAST to model the aero-hydro-servo-elastics of distinct turbines in the wind farm, and it is based on some of the principles of the Dynamic Wake Meandering (DWM) model, but avoids many of the limitations of existing DWM implementations.

Three Dimensional Simulations of Multiphase Flows Using a Lattice Boltzmann Method Suitable for High Density Ratios - 12126

Energy Technology Data Exchange (ETDEWEB)

Gokaltun, Seckin; McDaniel, Dwayne; Roelant, David [Applied Research Center, Florida International University, 10555 West Flagler Street, Suite 2100, Miami, FL 33174 (United States)

2012-07-01

Multiphase flows involving gas and liquid phases can be observed in engineering operations at various Department of Energy sites, such as mixing of slurries using pulsed-air mixers and hydrogen gas generation in liquid waste tanks etc. The dynamics of the gas phase in the liquid domain play an important role in the mixing effectiveness of the pulsed-air mixers or in the level of gas pressure build-up in waste tanks. To understand such effects, computational fluid dynamics methods (CFD) can be utilized by developing a three-dimensional computerized multiphase flow model that can predict accurately the behavior of gas motion inside liquid-filled tanks by solving the governing mathematical equations that represent the physics of the phenomena. In this paper, such a CFD method, lattice Boltzmann method (LBM), is presented that can model multiphase flows accurately and efficiently. LBM is favored over traditional Navier-Stokes based computational models since interfacial forces are handled more effectively in LBM. The LBM is easier to program, more efficient to solve on parallel computers, and has the ability to capture the interface between different fluid phases intrinsically. The LBM used in this paper can solve for the incompressible and viscous flow field in three dimensions, while at the same time, solve the Cahn-Hillard equation to track the position of the gas-liquid interface specifically when the density and viscosity ratios between the two fluids are high. This feature is of primary importance since the previous LBM models proposed for multiphase flows become unstable when the density ratio is larger than 10. The ability to provide stable and accurate simulations at large density ratios becomes important when the simulation case involves fluids such as air and water with a density ratio around 1000 that are common to many engineering problems. In order to demonstrate the capability of the 3D LBM method at high density ratios, a static bubble simulation is

Multi-phase alternative current machine winding design | Khan ...

African Journals Online (AJOL)

... single-phase to 18-phase excitation. Experimental results of a five-phase induction machine supplied from a static five-phase supply are provided to support the proposed design. Keywords: AC machine, Multi-phase machine, Stator winding, Five-phase. International Journal of Engineering, Science and Technology, Vol.

Artificial neural network and neutron application in a volume fraction calculation in annular and stratified multiphase system