Development and testing of a numerical code for treatment of complex river channel topography in three-dimensional CFD models with structured grids.

Abstract

The potential for using high-resolution numerical modelling to understand flow over complex rough heterogeneous surfaces has yet to be fully realized, largely due to problems of designing numerically stable meshes for use with complex bed geometries. Representation of such geometries has tended to rely upon sub-grid scale treatments involving roughness parameterization within numerical schemes. This paper develops, verifies and validates a technique for dealing with the representation of complex bed geometries within a basic numerical scheme. The method is based upon a numerical porosity treatment, which uses a structured grid but specifies cell porosities to block out bottom topography ( =1 for cells that are all water, P =0 for cells that are all bed and 0