The disclosure is directed to a computer-implemented method of representing fluid flow in a physical fluid reservoir. The method includes generating a mesh representation of the physical fluid reservoir having a plurality of mesh elements. Each of the plurality of mesh elements is representative of a regional portion of the fluid reservoir. The method further includes generating a matrix-based representation of fluid flow comprising matrix elements associated with a mesh element and selectively weighting the matrix elements based on fluid flow direction in the regional portion of the fluid reservoir represented by the mesh element associated with the matrix element.