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21 pages, 988 KiB

Open AccessArticle

Online Adaptive Local-Global Model Reduction for Flows in Heterogeneous Porous Media

by Yalchin Efendiev, Eduardo Gildin and Yanfang Yang

Computation 2016, 4(2), 22; https://doi.org/10.3390/computation4020022 - 7 Jun 2016

Cited by 29 | Viewed by 5632

Abstract

We propose an online adaptive local-global POD-DEIM model reduction method for flows in heterogeneous porous media. The main idea of the proposed method is to use local online indicators to decide on the global update, which is performed via reduced cost local multiscale [...] Read more.

We propose an online adaptive local-global POD-DEIM model reduction method for flows in heterogeneous porous media. The main idea of the proposed method is to use local online indicators to decide on the global update, which is performed via reduced cost local multiscale basis functions. This unique local-global online combination allows (1) developing local indicators that are used for both local and global updates (2) computing global online modes via local multiscale basis functions. The multiscale basis functions consist of offline and some online local basis functions. The approach used for constructing a global reduced system is based on Proper Orthogonal Decomposition (POD) Galerkin projection. The nonlinearities are approximated by the Discrete Empirical Interpolation Method (DEIM). The online adaption is performed by incorporating new data, which become available at the online stage. Once the criterion for updates is satisfied, we adapt the reduced system online by changing the POD subspace and the DEIM approximation of the nonlinear functions. The main contribution of the paper is that the criterion for adaption and the construction of the global online modes are based on local error indicators and local multiscale basis function which can be cheaply computed. Since the adaption is performed infrequently, the new methodology does not add significant computational overhead associated with when and how to adapt the reduced basis. Our approach is particularly useful for situations where it is desired to solve the reduced system for inputs or controls that result in a solution outside the span of the snapshots generated in the offline stage. Our method also offers an alternative of constructing a robust reduced system even if a potential initial poor choice of snapshots is used. Applications to single-phase and two-phase flow problems demonstrate the efficiency of our method. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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13 pages, 5862 KiB

Open AccessArticle

Pore-Network Modeling of Water and Vapor Transport in the Micro Porous Layer and Gas Diffusion Layer of a Polymer Electrolyte Fuel Cell

by Chao-Zhong Qin, S. Majid Hassanizadeh and Lucas M. Van Oosterhout

Computation 2016, 4(2), 21; https://doi.org/10.3390/computation4020021 - 30 May 2016

Cited by 21 | Viewed by 6539

Abstract

In the cathode side of a polymer electrolyte fuel cell (PEFC), a micro porous layer (MPL) added between the catalyst layer (CL) and the gas diffusion layer (GDL) plays an important role in water management. In this work, by using both quasi-static and [...] Read more.

In the cathode side of a polymer electrolyte fuel cell (PEFC), a micro porous layer (MPL) added between the catalyst layer (CL) and the gas diffusion layer (GDL) plays an important role in water management. In this work, by using both quasi-static and dynamic pore-network models, water and vapor transport in the MPL and GDL has been investigated. We illustrated how the MPL improved water management in the cathode. Furthermore, it was found that dynamic liquid water transport in the GDL was very sensitive to the built-up thermal gradient along the through-plane direction. Thus, we may control water vapor condensation only along GDL-land interfaces by properly adjusting the GDL thermal conductivity. Our numerical results can provide guidelines for optimizing GDL pore structures for good water management. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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9 pages, 3867 KiB

Open AccessArticle

Grand Canonical Monte Carlo Simulation of Nitrogen Adsorption in a Silica Aerogel Model

by Wen-Li Xie, Zheng-Ji Chen, Zeng Yao Li and Wen-Quan Tao

Computation 2016, 4(2), 18; https://doi.org/10.3390/computation4020018 - 1 Apr 2016

Cited by 6 | Viewed by 6497

Abstract

In this paper, the Diffusion Limited Cluster Aggregation (DLCA) method is employed to reconstruct the three-dimensional network of silica aerogel. Then, simulation of nitrogen adsorption at 77 K in silica aerogel is conducted by the Grand Canonical Monte Carlo (GCMC) method. To reduce [...] Read more.

In this paper, the Diffusion Limited Cluster Aggregation (DLCA) method is employed to reconstruct the three-dimensional network of silica aerogel. Then, simulation of nitrogen adsorption at 77 K in silica aerogel is conducted by the Grand Canonical Monte Carlo (GCMC) method. To reduce the computational cost and guarantee accuracy, a continuous-discrete hybrid potential model, as well as an adsorbed layer thickness estimation method, is employed. Four different structures are generated to investigate impacts of specific surface area and porosity on adsorptive capacity. Good agreement with experimental results is found over a wide range of relative pressures, which proves the validity of the model. Specific surface area and porosity mainly affect nitrogen uptake under low pressure and high pressure, respectively. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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33 pages, 630 KiB

Open AccessArticle

Analytical Results on the Behavior of a Liquid Junction across a Porous Diaphragm or a Charged Porous Membrane between Two Solutions According to the Nernst–Planck Equation

by Massimo Marino and Doriano Brogioli

Computation 2016, 4(2), 17; https://doi.org/10.3390/computation4020017 - 30 Mar 2016

Cited by 4 | Viewed by 5752

Abstract

We model the behavior of an ideal liquid junction, across a porous and possibly charged medium between two ion-containing solutions, by means of the Nernst–Planck equation for the stationary state, in conditions of local electroneutrality. An analytical solution of the equation was found [...] Read more.

We model the behavior of an ideal liquid junction, across a porous and possibly charged medium between two ion-containing solutions, by means of the Nernst–Planck equation for the stationary state, in conditions of local electroneutrality. An analytical solution of the equation was found long ago by Planck for the uncharged junction with only ions of valences +1 and −1. Other analytical results, which have later been obtained also for more general situations, seem impractical for performing calculations. In this paper, we obtain analytical solutions for systems with up to three valence classes, which can be applied to perform numerical calculations in a straightforward way. Our method provides a much larger amount of information on the behavior of the system than the well-known Henderson’s approximation. At the same time, it is more simple and reliable, and much less demanding in terms of computational effort, than the nowadays commonly employed numerical methods, typically based on discrete integration and trial-and-error numerical inversions. We present some examples of practical applications of our results. We study in particular the uphill transport (i.e., the transport from the lower-concentration to the higher-concentration region) of a divalent cation in a liquid junction containing also other univalent anions and cations. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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18 pages, 6658 KiB

Open AccessArticle

Bonding Strength Effects in Hydro-Mechanical Coupling Transport in Granular Porous Media by Pore-Scale Modeling

by Zhiqiang Chen, Chiyu Xie, Yu Chen and Moran Wang

Computation 2016, 4(1), 15; https://doi.org/10.3390/computation4010015 - 7 Mar 2016

Cited by 16 | Viewed by 6512

Abstract

The hydro-mechanical coupling transport process of sand production is numerically investigated with special attention paid to the bonding effect between sand grains. By coupling the lattice Boltzmann method (LBM) and the discrete element method (DEM), we are able to capture particles movements and [...] Read more.

The hydro-mechanical coupling transport process of sand production is numerically investigated with special attention paid to the bonding effect between sand grains. By coupling the lattice Boltzmann method (LBM) and the discrete element method (DEM), we are able to capture particles movements and fluid flows simultaneously. In order to account for the bonding effects on sand production, a contact bond model is introduced into the LBM-DEM framework. Our simulations first examine the experimental observation of “initial sand production is evoked by localized failure” and then show that the bonding or cement plays an important role in sand production. Lower bonding strength will lead to more sand production than higher bonding strength. It is also found that the influence of flow rate on sand production depends on the bonding strength in cemented granular media, and for low bonding strength sample, the higher the flow rate is, the more severe the erosion found in localized failure zone becomes. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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18 pages, 3218 KiB

Open AccessArticle

Contact Angle Effects on Pore and Corner Arc Menisci in Polygonal Capillary Tubes Studied with the Pseudopotential Multiphase Lattice Boltzmann Model

by Soyoun Son, Li Chen, Qinjun Kang, Dominique Derome and Jan Carmeliet

Computation 2016, 4(1), 12; https://doi.org/10.3390/computation4010012 - 20 Feb 2016

Cited by 21 | Viewed by 9917

Abstract

In porous media, pore geometry and wettability are determinant factors for capillary flow in drainage or imbibition. Pores are often considered as cylindrical tubes in analytical or computational studies. Such simplification prevents the capture of phenomena occurring in pore corners. Considering the corners [...] Read more.

In porous media, pore geometry and wettability are determinant factors for capillary flow in drainage or imbibition. Pores are often considered as cylindrical tubes in analytical or computational studies. Such simplification prevents the capture of phenomena occurring in pore corners. Considering the corners of pores is crucial to realistically study capillary flow and to accurately estimate liquid distribution, degree of saturation and dynamic liquid behavior in pores and in porous media. In this study, capillary flow in polygonal tubes is studied with the Shan-Chen pseudopotential multiphase lattice Boltzmann model (LBM). The LB model is first validated through a contact angle test and a capillary intrusion test. Then capillary rise in square and triangular tubes is simulated and the pore meniscus height is investigated as a function of contact angle θ. Also, the occurrence of fluid in the tube corners, referred to as corner arc menisci, is studied in terms of curvature versus degree of saturation. In polygonal capillary tubes, the number of sides leads to a critical contact angle θ_c which is known as a key parameter for the existence of the two configurations. LBM succeeds in simulating the formation of a pore meniscus at θ > θ_c or the occurrence of corner arc menisci at θ < θ_c. The curvature of corner arc menisci is known to decrease with increasing saturation and decreasing contact angle as described by the Mayer and Stoewe-Princen (MS-P) theory. We obtain simulation results that are in good qualitative and quantitative agreement with the analytical solutions in terms of height of pore meniscus versus contact angle and curvature of corner arc menisci versus saturation degree. LBM is a suitable and promising tool for a better understanding of the complicated phenomena of multiphase flow in porous media. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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9 pages, 1786 KiB

Open AccessArticle

Enhancing Computational Precision for Lattice Boltzmann Schemes in Porous Media Flows

by Farrel Gray and Edo Boek

Computation 2016, 4(1), 11; https://doi.org/10.3390/computation4010011 - 17 Feb 2016

Cited by 21 | Viewed by 5846

Abstract

We reassess a method for increasing the computational accuracy of lattice Boltzmann schemes by a simple transformation of the distribution function originally proposed by Skordos which was found to give a marginal increase in accuracy in the original paper. We restate the method [...] Read more.

We reassess a method for increasing the computational accuracy of lattice Boltzmann schemes by a simple transformation of the distribution function originally proposed by Skordos which was found to give a marginal increase in accuracy in the original paper. We restate the method and give further important implementation considerations which were missed in the original work and show that this method can in fact enhance the precision of velocity field calculations by orders of magnitude and does not lose accuracy when velocities are small, unlike the usual LB approach. The analysis is framed within the multiple-relaxation-time method for porous media flows, however the approach extends directly to other lattice Boltzmann schemes. First, we compute the flow between parallel plates and compare the error from the analytical profile for the traditional approach and the transformed scheme using single (4-byte) and double (8-byte) precision. Then we compute the flow inside a complex-structured porous medium and show that the traditional approach using single precision leads to large, systematic errors compared to double precision, whereas the transformed approach avoids this issue whilst maintaining all the computational efficiency benefits of using single precision. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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14 pages, 1849 KiB

Open AccessArticle

A New Method to Infer Advancement of Saline Front in Coastal Groundwater Systems by 3D: The Case of Bari (Southern Italy) Fractured Aquifer

by Costantino Masciopinto and Domenico Palmiotta

Computation 2016, 4(1), 9; https://doi.org/10.3390/computation4010009 - 16 Feb 2016

Cited by 6 | Viewed by 5491

Abstract

A new method to study 3D saline front advancement in coastal fractured aquifers has been presented. Field groundwater salinity was measured in boreholes of the Bari (Southern Italy) coastal aquifer with depth below water table. Then, the Ghyben-Herzberg freshwater/saltwater (50%) sharp interface and [...] Read more.

A new method to study 3D saline front advancement in coastal fractured aquifers has been presented. Field groundwater salinity was measured in boreholes of the Bari (Southern Italy) coastal aquifer with depth below water table. Then, the Ghyben-Herzberg freshwater/saltwater (50%) sharp interface and saline front position were determined by model simulations of the freshwater flow in groundwater. Afterward, the best-fit procedure between groundwater salinity measurements, at assigned water depth of 1.0 m in boreholes, and distances of each borehole from the modelled freshwater/saltwater saline front was used to convert each position (x, y) in groundwater to the water salinity concentration at depth of 1.0 m. Moreover, a second best-fit procedure was applied to the salinity measurements in boreholes with depth z. These results provided a grid file (x, y, z, salinity) suitable for plotting the actual Bari aquifer salinity by 3D maps. Subsequently, in order to assess effects of pumping on the saltwater-freshwater transition zone in the coastal aquifer, the Navier-Stokes (N-S) equations were applied to study transient density-driven flow and salt mass transport into freshwater of a single fracture. The rate of seawater/freshwater interface advancement given by the N-S solution was used to define the progression of saline front in Bari groundwater, starting from the actual salinity 3D map. The impact of pumping of 335 L·s⁻¹ during the transition period of 112.8 days was easily highlighted on 3D salinity maps of Bari aquifer. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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11 pages, 462 KiB

Open AccessArticle

Applications of Computational Modelling and Simulation of Porous Medium in Tissue Engineering

by Carrie L. German and Sundararajan V. Madihally

Computation 2016, 4(1), 7; https://doi.org/10.3390/computation4010007 - 6 Feb 2016

Cited by 13 | Viewed by 7696

Abstract

In tissue engineering, porous biodegradable scaffolds are used as templates for regenerating required tissues. With the advances in computational tools, many modeling approaches have been considered. For example, fluid flow through porous medium can be modeled using the Brinkman equation where permeability of [...] Read more.

In tissue engineering, porous biodegradable scaffolds are used as templates for regenerating required tissues. With the advances in computational tools, many modeling approaches have been considered. For example, fluid flow through porous medium can be modeled using the Brinkman equation where permeability of the porous medium has to be defined. In this review, we summarize various models recently reported for defining permeability and non-invasive pressure drop monitoring as a tool to validate dynamic changes in permeability. We also summarize some models used for scaffold degradation and integrating mass transport in the simulation. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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19 pages, 1536 KiB

Open AccessArticle

Modeling Groundwater Flow in Heterogeneous Porous Media with YAGMod

by Laura Cattaneo, Alessandro Comunian, Giovanna De Filippis, Mauro Giudici and Chiara Vassena

Computation 2016, 4(1), 2; https://doi.org/10.3390/computation4010002 - 29 Dec 2015

Cited by 8 | Viewed by 7309

Abstract

Modeling flow and transport in porous media requires the management of complexities related both to physical processes and to subsurface heterogeneity. A thorough approach needs a great number of spatially-distributed phenomenological parameters, which are seldom measured in the field. For instance, modeling a [...] Read more.

Modeling flow and transport in porous media requires the management of complexities related both to physical processes and to subsurface heterogeneity. A thorough approach needs a great number of spatially-distributed phenomenological parameters, which are seldom measured in the field. For instance, modeling a phreatic aquifer under high water extraction rates is very challenging, because it requires the simulation of variably-saturated flow. 3D steady groundwater flow is modeled with YAGMod (yet another groundwater flow model), a model based on a finite-difference conservative scheme and implemented in a computer code developed in Fortran90. YAGMod simulates also the presence of partially-saturated or dry cells. The proposed algorithm and other alternative methods developed to manage dry cells in the case of depleted aquifers are analyzed and compared to a simple test. Different approaches yield different solutions, among which, it is not possible to select the best one on the basis of physical arguments. A possible advantage of YAGMod is that no additional non-physical parameter is needed to overcome the numerical difficulties arising to handle drained cells. YAGMod also includes a module that allows one to identify the conductivity field for a phreatic aquifer by solving an inverse problem with the comparison model method. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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19 pages, 663 KiB

Open AccessFeature PaperArticle

Reduced Numerical Model for Methane Hydrate Formation under Conditions of Variable Salinity. Time-Stepping Variants and Sensitivity

by Malgorzata Peszynska, Francis Patricia Medina, Wei-Li Hong and Marta E. Torres

Computation 2016, 4(1), 1; https://doi.org/10.3390/computation4010001 - 24 Dec 2015

Cited by 4 | Viewed by 5669

Abstract

In this paper, we consider a reduced computational model of methane hydrate formation in variable salinity conditions, and give details on the discretization and phase equilibria implementation. We describe three time-stepping variants: Implicit, Semi-implicit, and Sequential, and we compare the accuracy and efficiency [...] Read more.

In this paper, we consider a reduced computational model of methane hydrate formation in variable salinity conditions, and give details on the discretization and phase equilibria implementation. We describe three time-stepping variants: Implicit, Semi-implicit, and Sequential, and we compare the accuracy and efficiency of these variants depending on the spatial and temporal discretization parameters. We also study the sensitivity of the model to the simulation parameters and in particular to the reduced phase equilibria model. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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14 pages, 4486 KiB

Open AccessArticle

Molecular Simulation of Shale Gas Adsorption and Diffusion in Clay Nanopores

by Hongguang Sui, Jun Yao and Lei Zhang

Computation 2015, 3(4), 687-700; https://doi.org/10.3390/computation3040687 - 11 Dec 2015

Cited by 55 | Viewed by 11529

Abstract

The present work aims to study the adsorption behavior and dynamical properties of CH₄ in clay slit pore with or without cation exchange structures at sizes of 1.0 nm–4.0 nm using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) methods. The [...] Read more.

The present work aims to study the adsorption behavior and dynamical properties of CH₄ in clay slit pore with or without cation exchange structures at sizes of 1.0 nm–4.0 nm using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) methods. The adsorption isotherms of CH₄ have been investigated by GCMC simulations at different temperatures and various pore sizes. In the montmorillonite (MMT) clays without a cation exchange structure, from the density profile, we find the molecules preferentially adsorb onto the surface, and only an obvious single layer was observed. The general trend within slit pores is that with increasing pore width, the adsorbed amount will increase. However, the larger pores exhibit lower excess density and the smaller pores exhibit higher excess density. The preloaded water will reduce CH₄ sorption. The in plane self-diffusion coefficient of CH₄ which is investigated by MD simulations combined with Einstein fluid equation increases rapidly with the pore size increasing at low pressure. Under these given conditions, the effect of temperature has little influence on the in-plane self-diffusion coefficient. In the MMT clays with cation exchange structure, cation exchange has little effect on CH₄ adsorption and self-diffusion. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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17 pages, 347 KiB

Open AccessArticle

Multiscale Simulations for Coupled Flow and Transport Using the Generalized Multiscale Finite Element Method

by Eric T. Chung, Yalchin Efendiev, Wing Tat Leung and Jun Ren

Computation 2015, 3(4), 670-686; https://doi.org/10.3390/computation3040670 - 11 Dec 2015

Cited by 5 | Viewed by 5610

Abstract

In this paper, we develop a mass conservative multiscale method for coupled flow and transport in heterogeneous porous media. We consider a coupled system consisting of a convection-dominated transport equation and a flow equation. We construct a coarse grid solver based on the [...] Read more.

In this paper, we develop a mass conservative multiscale method for coupled flow and transport in heterogeneous porous media. We consider a coupled system consisting of a convection-dominated transport equation and a flow equation. We construct a coarse grid solver based on the Generalized Multiscale Finite Element Method (GMsFEM) for a coupled system. In particular, multiscale basis functions are constructed based on some snapshot spaces for the pressure and the concentration equations and some local spectral decompositions in the snapshot spaces. The resulting approach uses a few multiscale basis functions in each coarse block (for both the pressure and the concentration) to solve the coupled system. We use the mixed framework, which allows mass conservation. Our main contributions are: (1) the development of a mass conservative GMsFEM for the coupled flow and transport; (2) the development of a robust multiscale method for convection-dominated transport problems by choosing appropriate test and trial spaces within Petrov-Galerkin mixed formulation. We present numerical results and consider several heterogeneous permeability fields. Our numerical results show that with only a few basis functions per coarse block, we can achieve a good approximation. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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16 pages, 5315 KiB

Open AccessArticle

An Incompressible, Depth-Averaged Lattice Boltzmann Method for Liquid Flow in Microfluidic Devices with Variable Aperture

by Artin Laleian, Albert J. Valocchi and Charles J. Werth

Computation 2015, 3(4), 600-615; https://doi.org/10.3390/computation3040600 - 24 Nov 2015

Cited by 11 | Viewed by 6067

Abstract

Two-dimensional (2D) pore-scale models have successfully simulated microfluidic experiments of aqueous-phase flow with mixing-controlled reactions in devices with small aperture. A standard 2D model is not generally appropriate when the presence of mineral precipitate or biomass creates complex and irregular three-dimensional (3D) pore [...] Read more.

Two-dimensional (2D) pore-scale models have successfully simulated microfluidic experiments of aqueous-phase flow with mixing-controlled reactions in devices with small aperture. A standard 2D model is not generally appropriate when the presence of mineral precipitate or biomass creates complex and irregular three-dimensional (3D) pore geometries. We modify the 2D lattice Boltzmann method (LBM) to incorporate viscous drag from the top and bottom microfluidic device (micromodel) surfaces, typically excluded in a 2D model. Viscous drag from these surfaces can be approximated by uniformly scaling a steady-state 2D velocity field at low Reynolds number. We demonstrate increased accuracy by approximating the viscous drag with an analytically-derived body force which assumes a local parabolic velocity profile across the micromodel depth. Accuracy of the generated 2D velocity field and simulation permeability have not been evaluated in geometries with variable aperture. We obtain permeabilities within approximately 10% error and accurate streamlines from the proposed 2D method relative to results obtained from 3D simulations. In addition, the proposed method requires a CPU run time approximately 40 times less than a standard 3D method, representing a significant computational benefit for permeability calculations. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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16 pages, 1899 KiB

Open AccessArticle

Effective Thermal Conductivity of MOF-5 Powder under a Hydrogen Atmosphere

by Hui Wang, Zhiguo Qu, Wen Zhang and Wenquan Tao

Computation 2015, 3(4), 558-573; https://doi.org/10.3390/computation3040558 - 6 Nov 2015

Cited by 5 | Viewed by 8061

Abstract

Effective thermal conductivity is an important thermophysical property in the design of metal-organic framework-5 (MOF-5)-based hydrogen storage tanks. A modified thermal conductivity model is built by coupling a theoretical model with the grand canonical Monte Carlo simulation (GCMC) to predict the effect of [...] Read more.

Effective thermal conductivity is an important thermophysical property in the design of metal-organic framework-5 (MOF-5)-based hydrogen storage tanks. A modified thermal conductivity model is built by coupling a theoretical model with the grand canonical Monte Carlo simulation (GCMC) to predict the effect of the H₂ adsorption process on the effective thermal conductivity of a MOF-5 powder bed at pressures ranging from 0.01 MPa to 50 MPa and temperatures ranging from 273.15 K to 368.15 K. Results show that the mean pore diameter of the MOF-5 crystal decreases with an increase in pressure and increases with an increase in temperature. The thermal conductivity of the adsorbed H₂ increases with an increased amount of H₂ adsorption. The effective thermal conductivity of the MOF-5 crystal is significantly enhanced by the H₂ adsorption at high pressure and low temperature. The effective thermal conductivity of the MOF-5 powder bed increases with an increase in pressure and remains nearly unchanged with an increase in temperature. The thermal conductivity of the MOF-5 powder bed increases linearly with the decreased porosity and increased thermal conductivity of the skeleton of the MOF-5 crystal. The variation in the effective thermal conductivities of the MOF-5 crystals and bed mainly results from the thermal conductivities of the gaseous and adsorption phases. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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17 pages, 1259 KiB

Open AccessArticle

Numerical Simulation of Fluid-Solid Coupling in Fractured Porous Media with Discrete Fracture Model and Extended Finite Element Method

by Qingdong Zeng and Jun Yao

Computation 2015, 3(4), 541-557; https://doi.org/10.3390/computation3040541 - 30 Oct 2015

Cited by 10 | Viewed by 7873

Abstract

Fluid-solid coupling is ubiquitous in the process of fluid flow underground and has a significant influence on the development of oil and gas reservoirs. To investigate these phenomena, the coupled mathematical model of solid deformation and fluid flow in fractured porous media is [...] Read more.

Fluid-solid coupling is ubiquitous in the process of fluid flow underground and has a significant influence on the development of oil and gas reservoirs. To investigate these phenomena, the coupled mathematical model of solid deformation and fluid flow in fractured porous media is established. In this study, the discrete fracture model (DFM) is applied to capture fluid flow in the fractured porous media, which represents fractures explicitly and avoids calculating shape factor for cross flow. In addition, the extended finite element method (XFEM) is applied to capture solid deformation due to the discontinuity caused by fractures. More importantly, this model captures the change of fractures aperture during the simulation, and then adjusts fluid flow in the fractures. The final linear equation set is derived and solved for a 2D plane strain problem. Results show that the combination of discrete fracture model and extended finite element method is suited for simulating coupled deformation and fluid flow in fractured porous media. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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Jump to: Research

24 pages, 16521 KiB

Open AccessReview

CFD Simulation and Experimental Analyses of a Copper Wire Woven Heat Exchanger Design to Improve Heat Transfer and Reduce the Size of Adsorption Beds

by John White

Computation 2016, 4(1), 8; https://doi.org/10.3390/computation4010008 - 6 Feb 2016

Cited by 4 | Viewed by 10542

Abstract

The chief objective of this study is the proposal design and CFD simulation of a new compacted copper wire woven fin heat exchanger and silica gel adsorbent bed used as part of an adsorption refrigeration system. This type of heat exchanger design has [...] Read more.

The chief objective of this study is the proposal design and CFD simulation of a new compacted copper wire woven fin heat exchanger and silica gel adsorbent bed used as part of an adsorption refrigeration system. This type of heat exchanger design has a large surface area because of the wire woven fin design. It is estimated that this will help improve the coefficient of performance (COP) of the adsorption phase and increase the heat transfer in this system arrangement. To study the heat transfer between the fins and porous adsorbent reactor bed, two experiments were carried out and matched to computational fluid dynamics (CFD) results. Full article

(This article belongs to the Special Issue Advances in Modeling Flow and Transport in Porous Media)

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