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This paper presents an electrochemical–thermal–hydraulic–mechanical (ETHM) coupling model by introducing the electrolyte flow field into the model of lithium-ion batteries (LIBs). First, the ETHM coupling model is established on the basis of the electrochemical–thermal–mechanical (ETM) coupling model and poroelasticity model. Then, the ETHM coupling model for the discharge of LIBs is numerically resolved and verified against the ETM coupling model using the commercial 11.5 Ah LiMn2O4 battery as an example. Subsequently, the flow and deformation characteristics (such as the Darcy's velocity, the pore pressure, the Péclet number, and the volumetric strain) are analyzed. The results suggest that the electrolyte does flow during the operation of LIBs. Furthermore, the electrolyte flow is governed by the internal pore pressure gradient induced by the poroelastic effect. The electrolyte flow behavior is also influenced by the boundary conditions. The findings in this study are of benefit to obtain in-depth understanding of the coupling mechanisms among the electrolyte flow field and the stress (strain) field, the temperature field, and the electrochemical field. [ABSTRACT FROM AUTHOR]

This paper numerically investigates the heat transfer performance of thermally developing non-Darcy forced convection in a fluid-saturated porous medium tube under asymmetric entrance temperature boundary conditions. The Brinkman flow model and the local thermal non-equilibrium (LTNE) model are employed to establish the mathematical model of the studied problem to predict the forced convective heat transfer. Then, the mathematical model is numerically solved using COMSOL Multiphysics. Consequently, the fluid velocity field, the solid temperature field, the fluid temperature field and the Nusselt number are obtained. Moreover, the dependences of the Nusselt number on some key parameters are analyzed in detail. The results show that the distribution characteristics of the Nusselt number are strongly dependent on the form of the entrance temperature function. Meanwhile, it is found that the Nusselt number increases first and then tends to approach an asymptotic value with the increase in the Darcy number and the Biot number. The Nusselt number monotonously increases with increasing the Péclet number. On the contrary, the Nusselt number decreases first and then tends to be an asymptotic value owing to the increase in the thermal conductivity ratio and the viscosity ratio. This study is of benefit to provide in-depth insights into the non-Darcy forced convective heat transfer in porous tubes with asymmetric inlet temperature under LTNE condition. [ABSTRACT FROM AUTHOR]

• Fully coupled THM model of porous media under LTNE condition is presented. • T s is always higher than T f due to the LTNE effect. • Dependences of multi-physical fields on the pertinent parameters are investigated. This paper presents a fully coupled thermo-hydro-mechanical (THM) model of a fluid-saturated and compressible porous medium under local thermal non-equilibrium (LTNE) condition and carries out the corresponding numerical simulation. First, the coupling among the temperature field, the pore fluid pressure field, and the solid stress/displacement field is fulfilled by means of strong explicit coupling of governing equations in this study. Then, the presented model is applied to the THM coupling problem in an infinite porous medium with a cylindrical borehole subjected to uniform fluid pressure and temperature at the borehole boundary. Subsequently, the partial differential equations (PDEs) module in COMSOL Multiphysics software is employed to numerically solve the studied problem. Consequently, the finite element solutions of the pore fluid pressure field, the strain/stress fields and the two temperature fields of pore fluid and skeleton solid are obtained, and the spatial-temporal distribution characteristics of the above multi-physical fields are investigated. Finally, the corresponding parametric studies are carried out. The numerical results show that the stress decreases with the increase of the bulk volumetric thermal expansion coefficient of porous media. And the pore pressure decreases when the pore fluid mobility increases. Meanwhile, it is found in this work that the solid temperature is always higher than that of pore fluid due to the LTNE effect. Besides, with increasing the specific solid–fluid interfacial heat transfer coefficient, the solid temperature decreases, while the temperature of pore fluid increases. Accordingly, the temperature difference between the solid and the pore fluid diminishes. In addition, the thermal conductivity of solid grains has a greater impact on the solid temperature but has a limited impact on the temperature of pore fluid, and vice versa. The findings in this work are of benefit to obtain in-depth understanding of THM fully coupling mechanism and LTNE effect in a fluid-saturated porous medium. [ABSTRACT FROM AUTHOR]

In engineering practices, different numerical methods for fluid flow simulation and solid deformation/stress simulation are adopted to model fluid-structure interaction problems in porous media. Cell-centered finite volume method is widely used in fluid flow simulation, while the solid deformation/stress simulation is usually accomplished by using the Galerkin vertex-centered finite element method, which leads to the incompatibility between cell variables with nodal variables. Therefore, the data transfer between cell variables and nodal variables is inevitable. Consequently, this kind of transfer will lead to extra artificial error. Hence, the major concern is how to minimize the error due to cell to node projections. In this paper, a problem of pore pressure diffusion within a one-dimensional heterogeneous porous medium is investigated. We present a new projection scheme and corresponding error formula, where the error control factor is introduced. The new projection scheme is based on piecewise linear interpolations. Results demonstrate that if the error control factor is chosen properly, the error due to the projection from cell to node can be controlled effectively, and the most desired zero error can be achieved. Finally, we analyze some practical cases in consideration of permeability contrast and mesh uniformity. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY An analytical solution is proposed for transient flow and deformation coupling of a fluid-saturated poroelastic medium within a finite two-dimensional (2-D) rectangular domain. In this study, the porous medium is assumed to be isotropic, homogeneous, and compressible. In addition, the point sink can be located at an arbitrary position in the porous medium. The fluid-solid interaction in porous media is governed by the general Biot's consolidation theory. The method of integral transforms is applied in the analytical formulation of closed-form solutions. The proposed analytical solution is then verified against both exact and numerical results. The analytical solution is first simplified and validated by comparison with an existing exact solution for the uncoupled problem. Then, a case study for pumping from a confined aquifer is performed. The consistency between the numerical solution and the analytical solution confirms the accuracy and reliability of the analytical solution presented in this paper. The proposed analytical solution can help us to obtain in-depth insights into time-dependent mechanical behavior due to fluid withdrawal within finite 2-D porous media. Moreover, it can also be of great significance to calibrate numerical solutions in plane strain poroelasticity and to formulate relevant industry norms and standards. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• An arbitrarily-shaped hole element is constructed for thermal analysis of cellular materials. • T-complete solutions are sought by introducing the charge simulation method. • The final element stiffness equation involves boundary integrals only. • The proposed method can capture the local effects with high accuracy without mesh refinement. Special finite elements are developed which adequately represent the state of heat conduction in the region around an arbitrarily-shaped hole. This is achieved with two assumed temperature fields. The frame field is defined along the element boundary while the intra-element field is independently approximated by using truncated T-complete solutions as trial functions for capturing hole effects. The geometrical irregularity of holes contribute to the difficulty in seeking T-complete solutions. By means of the charge simulation method and numerical conformal mapping technique, the systematic construction of T-complete solutions is shown which satisfy a priori the governing differential equation. Based on the modified variational principle, the two independent temperature fields are linked together at the element level, ensuring conformity across inter-element boundaries. The resultant element stiffness equation involves boundary integrals only, which provides a great flexibility in mesh generation with polygons. Numerical examples for the problems with a single, dual, and multiple holes are given to illustrate the efficiency and accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

Hybrid Trefftz Voronoi finite elements on polygon meshes are developed to capture thermal response of heterogeneous materials with randomly dispersed inclusions/voids. In this approach, the temperature intra-element field within the polygon is approximated by the homogeneous solutions to the heat conduction governing equation which are also called the T-complete functions. Whereas an auxiliary temperature frame field is independently defined on the polygonal boundary. The continuity at the matrix–inclusion interface is guaranteed by exterior and interior T-complete functions and that across element boundaries is enforced by incorporating the known hybrid functional at the element level. Thus, only the hybrid functional should be established for the matrix region. In conjunction with the divergence theorem, the domain integral involved in the functional vanishes, which leads to the element stiffness equation including boundary integrals only. It is reported that there exists a linear relationship between the maximum number of T-complete functions and the number of Gauss points sampled on each element side. Numerical results demonstrate that the proposed methodology is remarkably more efficient than the conventional finite element method (ABAQUS) and consequently becomes popular in micromechanical and microthermal modeling of composite and porous materials. [ABSTRACT FROM AUTHOR]