Sharif Digital Repository

In this paper, flow of multi-component two-phase fluids in highly heterogeneous anisotropic two-dimensional porous media is studied using computational methods suitable for unstructured triangular and/or quadrilateral grids. The physical model accounts for miscibility and compressibility of fluids while gravity and capillary effects are neglected. The governing equations consist of a pressure equation together with a system of mass conservation equations. For solving pressure equation, a new method called Control Volume Distributed Finite Element Method (CVDFEM) is introduced which uses Control Volume Distributed (CVD) vertex-centered grids. It is shown that the proposed method is able to... 

Purpose: This paper aims to numerically study the compositional flow of two- and three-phase fluids in one-dimensional porous media and to make a comparison between several upwind and central numerical schemes. Design/methodology/approach: Implicit pressure explicit composition (IMPEC) procedure is used for discretization of governing equations. The pressure equation is solved implicitly, whereas the mass conservation equations are solved explicitly using different upwind (UPW) and central (CEN) numerical schemes. These include classical upwind (UPW-CLS), flux-based decomposition upwind (UPW-FLX), variable-based decomposition upwind (UPW-VAR), Roe’s upwind (UPW-ROE), local Lax–Friedrichs... 

Purpose - In this paper, the flow of multiphase fluids in a one-dimensional homogeneous porous media involving the gravity effects is numerically studied using the dominant wave method. The paper aims to discuss these issues. Design/methodology/approach - The numerical scheme used for solving the pressure equations, obtained for the black-oil model, is a backward Euler scheme while the hyperbolic mass conservation equations, derived for both black-oil and Buckley-Leverett models, are solved using the dominant wave method. Higher-order schemes are achieved using either variable derivatives along with the minmod limiter or a MUSCL type interface construction scheme using the Fromm's limiter.... 

Sedimentation of particles can undermine the uniformity of the product in the manufacture of the particle-filled composites. An adequate mathematical description of the sedimentation process could be helpful for providing necessary information concerning the dominant parameters and can give an insight for the process designer to prevent such an undesirable phenomenon in composite production. The present article deals with the mathematical modeling of settling particles during curing of polymer matrix composites. The sedimentation process is described by the mass conservation law for particles. Since the viscosity of the suspending polymer increases as a result of curing process, a new model... 

Both the grid movement scheme and the moving grid solver are considered. A new grid movement scheme for large amplitude moving boundaries such as store separation has been developed. Some popular grid movement methods have been studied to analyse capabilities of this method. In fact, this scheme could be an optimal combination of the overset grids method and the local remeshing as it uses their advantages and avoids some of their disadvantages. To have valid solution in moving grids, two conservation laws, which preserve independences of solution from grid motions, have been considered. These constraints, which are called Geometric Conservation Laws (GCL), have been satisfied implicitly... 

Gravity drainage is known to be one of the most effective methods for oil recovery in fractured reservoirs. In this study, both free fall and controlled gravity drainage processes were studied using a transparent fractured experimental model, followed by modelling using commercial CFD software. The governing equations were employed based on the Darcy and mass conservation laws and partial pressure formulation. Comprehensive examination was done on variables such as fluid saturation, velocity, and pressure distribution in the matrix and fracture, as well as fluid front level and production rate. Additionally, effects of the model parameters on the gravity drainage performance were... 

In this work, an efficient bi-implicit strategy is suitably developed within the context of a hybrid finite volume element method to solve axisymmetric turbulent reactive flow in a model gas turbine combustor. Based on the essence of a control-volume-based finite-element method, the formulation benefits from the geometrical flexibility of the finite element methods while the discrete algebraic governing equations are derived through applying the conservation laws to discrete cells distributed in the solution domain. To enhance the efficiency of method, we extend the physical influence upwinding scheme to cylindrical coordinates. This extension helps to improve the advection flux... 

The objective of this study is to develop and apply an arbitrary Lagrangian-Eulerian unstructured finite-volume lattice-Boltzmann method (ALE-FVLBM) for solving two-dimensional compressible inviscid flows around moving bodies. The two-dimensional compressible form of the LB equation is considered and the resulting LB equation is formulated in the ALE framework on an unstructured body-fitted mesh to correctly model the body shape and properly incorporate the mesh movement due to the body motion. The spatial discretization of the resulting system of equations is performed by a second-order cell-centered finite-volume method on arbitrary quadrilateral meshes and an implicit dual-time stepping... 

In this paper, a numerical model is developed based on the X-FEM technique to simulate the transport of dense solute in a single fluid phase through the fractured porous media. The governing equation is based on the mass conservation law which is applied to the fluid phase and the solute in both matrix and fracture domain. The integral governing equations of the mass exchange between the fracture and the surrounding matrix is derived. The extended finite element method (X-FEM) is applied by employing appropriate enrichment functions to model the fractured porous domain. The superiority of the X-FEM is that the FE mesh is not necessary to be conformed to the fracture geometry, so the regular... 

In this paper, a fully coupled numerical model is developed based on the X-FEM technique to simulate the reactive acid transport in fractured porous media. The porous medium consists of the solid and fluid phases, in which the fluid phase includes water and acid components, and chemical reactions can be occurred between acid component and solid phase at the solid–fluid interfaces. The governing equations include the mass and momentum conservation laws for fluid phase, and the advective–diffusive transport of acid component that must be solved to obtain the primary unknowns, including the pore fluid pressure, acid concentration, and fluid velocity vector. Applying the... 

In this work, the conservation forms of the reacting ow governing equations are treated mainly using a cell-centered finite-volume approach with a collocated storage of all trans- port variables. However, the finite volume formulations are suitably incorporated with the finite element expressions. As an innovation, a physical influence upwinding scheme is suitably extended to the cylindrical coordinate system to approximate the convective terms of the governing conservation laws at the cell faces. This treatment firstly respects the physics of flow and secondly provides the necessary coupling of velocity and pressure fields in this frame. The numerical solution of laminar, buoyant difiusion... 

Membrane reactors are an advanced technology with vast application capacities for equilibrium limited endothermic reactions. The main propose of this study is to offer an optimized packed-bed membrane steam methane reforming (SMR) tubular reactor for sustainable CH4 conversion by implementing triple-objective optimization model based on optimum H2/CO ratio for low temperature Fischer-Tropsch (F-T) process. In this study a one dimensional pseudo-homogeneous model based on mass, energy, and momentum conservation laws is used to simulate the behavior of a packed-bed membrane reactor for production of syngas by SMR. In the optimization section, the proposed work explores optimal values of...