Analysis of an interior penalty discontinuous Galerkin scheme for two phase flow in porous media with dynamic capillarity effects

We present an interior penalty discontinuous Galerkin scheme for two-phase flow with dynamic capillary pressure effects. The mass-conservation laws are approximated directly, without the introduction of a global pressure. We prove existence and convergence of the scheme and obtain error-estimates for sufficiently smooth data

A class of degenerate pseudo-parabolic equations : existence, uniqueness of weak solutions, and error estimates for the Euler-implicit discretization

In this paper, we investigate a class of degenerate pseudo-parabolic equations. Such equations model two-phase flow in porous media where dynamic effects are included in the capillary pressure. The existence and uniqueness of a weak solution are proved, and error estimates for an Euler implicit time discretization are obtained

Regularization schemes for degenerate Richards equations and outflow conditions

We analyze regularization schemes for the Richards equation and a time discrete numerical approximation. The original equations can be doubly degenerate, therefore they may exhibit fast and slow diffusion. Additionally, we treat outflow conditions that model an interface separating the porous medium from a free flow domain. In both situations we provide a regularization with a non-degenerate equation and standard boundary conditions, and discuss the convergence rates of the approximations

Analysis and upscaling of a reactive transport model in fractured porous media involving nonlinear a transmission condition

We consider a reactive transport model in a fractured porous medium. The particularity appears in the conditions imposed at the interface separating the block and the fracture, which involves a nonlinear transmission condition. Assuming that the fracture has thickness e, we analyze the resulting problem and prove the convergence towards a reduced model in the limit e ¿ 0. The resulting is a model defined on an interface (the reduced fracture) and acting as a boundary condition for the equations defined in the block. Using both formal and rigorous arguments, we obtain the reduced models for different flow regimes, expressed through a moderate, or a high Péclet number. Keywords: Fractured porous media; Upscaling; Reactive transport; Nonlinear transmission condition

Analysis and upscaling of a reactive transport model in fractured porous media involving nonlinear a transmission condition

We consider a reactive transport model in a fractured porous medium. The particularity appears in the conditions imposed at the interface separating the block and the fracture, which involves a nonlinear transmission condition. Assuming that the fracture has thickness e, we analyze the resulting problem and prove the convergence towards a reduced model in the limit e ¿ 0. The resulting is a model defined on an interface (the reduced fracture) and acting as a boundary condition for the equations defined in the block. Using both formal and rigorous arguments, we obtain the reduced models for different flow regimes, expressed through a moderate, or a high Péclet number. Keywords: Fractured porous media; Upscaling; Reactive transport; Nonlinear transmission condition

An a posterior error estimate for vertex-centered finite volume discretizations of immiscible incompressible two-phase flow

In this paper we derive an a posteriori error estimate for the numerical approximation of the solution of a system modeling the flow of two incompressible and immiscible fluids in a porous medium. We take into account the capillary pressure, which leads to a coupled system of two equations: parabolic and elliptic. The parabolic equation may become degenerate, i.e., the nonlinear diffusion coefficient may vanish over regions that are not known a priori. We first show that, under appropriate assumptions, the energy-type-norm differences between the exact and the approximate nonwetting phase saturations, the global pressures, and the Kirchhoff transforms of the nonwetting phase saturations can be bounded by the dual norm of the residuals. We then bound the dual norm of the residuals by fully computable a posteriori estimators. Our analysis covers a large class of conforming, vertex-centered finite volume-type discretizations with fully implicit time stepping. As an example, we focus here on two approaches: a "mathematical" scheme derived from the weak formulation, and a phase-by-phase upstream weighting "engineering" scheme. Finally, we show how the different error components, namely the space discretization error, the time discretization error, the linearization error, the algebraic solver error, and the quadrature error can be distinguished and used for making the calculations efficient