A comparison of finite volume formulations and coupling strategies for two-phase flow in deforming porous media. (June 2015)

• Record Type: Journal Article
• Authors: Asadi, Roza; Ataie-Ashtiani, Behzad
• Is Part Of: Computers and geotechnics. Volume 67(2015)
• Page Start: 17
• Page End: 32
• Publication Date: 2015-06
• Subjects: Finite volume method -- Two phase flow -- Deformable porous media -- Primary variables -- Picard scheme -- Fully coupled -- Iteratively coupled; Engineering geology -- Data processing -- Periodicals; Soil mechanics -- Data processing -- Periodicals; Rock mechanics -- Data processing -- Periodicals; 624.1510285
• DOI: 10.1016/j.compgeo.2015.02.004
• Languages: English
• ISSNs: 0266-352X

Abstract

Abstract: In this paper a locally mass conservative finite volume method is employed to model the one-dimensional, two-phase immiscible flow in a poroelastic media. Since, an appropriate choice of primary variables is critical in simulating multiphase subsurface flow, depending on such a choice, the governing equations can be expressed in different forms. By implementing Picard iteration to a highly nonlinear system of equations, three numerical models including pressure form, mixed form and mixed form with a modified Picard linearization are developed in this study. These models have been evaluated in terms of stability, convergence and mass conservation in various one-dimensional test cases. Selecting water saturation in the mixed form as a primary variable, which is not frequent in the geotechnical engineering, could produce convergence problems in transition from saturated to unsaturated regimes, but in other conditions show good convergence and also mass balance properties. The pressure form and the mixed form with a modified Picard linearization converge in all test cases even near the fully saturated conditions. The pressure form suffers from poor mass balance and the mixed form with a modified Picard linearization poses superior mass balance property than the pressure form. In order to solve the coupled multiphase flow and geomechanics, two coupling strategies are used, first the fully coupled approach and second the iterative algorithm based on the fixed-stress operator split. Comparison between the total number of iterations and the total execution time of the fully coupled method and the fixed-stress schemes are presented through different one-dimensional examples. The accuracy, robustness and efficiency of the fixed-stress method have been demonstrated due to the reduced CPU time and low values of error for different variables.