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Institut für Wasserbau - IWS

Selected Topics and International Network Lectures

Druckansicht
 
Dienstag
10.01.2006
16:00 Uhr
Dr. Ivan Lunati, Inst.f. Hydromechanik u. Wasserwirtschaft, ETH Zürich

A Multiscale Finite-Volume Framework for Modeling Multiphase Flow

A multi-scale finite-volume (MSFV) method for solving multiphase flow problem in highly heterogeneous media was recently developed. In contrast with classical upscaling techniques, the goal of multiscale methods is not simply to capture the large-scale effects of the fine-scale heterogeneity, but to provide an efficient tool for solving large flow problems with fine-scale resolution. The MSFV is based on a fractional flow formulation of the problem: first an equation for the total velocity is solved, then a fine-scale velocity field is reconstructed, finally the phase-saturation distribution is obtained by solving the nonlinear transport equations. In addition to the original fine grid the MSFV method employs an imposed coarse grid and a dual coarse grid. The first step is to compute the effective parameters that have to be used for solving the global flow problem on a coarse grid. This is done by means of a set of basis functions, which are numerical solutions computed on the cells of the dual grid. From these basis functions, the fluxes across the coarse-block boundaries are computed and the transmissibilities are extracted. Then the conservative fine-scale total-velocity field is reconstructed by solving a local flow problem in each coarse cell.