An unstructured finite-volume algorithm for predicting flow in rivers and estuaries

A numerical algorithm is presented for the solution of geometrically challenging two-dimensional river and estuary flows, based on an adaptive triangular tessellation of the how domains of interest. The governing, shallow water, equations are discretised using st finite volume approach embodying variable step time integrators, to yield a method that is second order accurate in both space and time. An approximate Riemann solver is used to determine flow directionality in conjunction with an effective means of dealing with wetting and drying at the boundaries. The approach is capable of handling complex flow domains and yielding solutions for which errors are controlled automatically by the use of spatial re-gridding and time stepping based on local error estimates. Its range of applicability is demonstrated through considering several problems involving super/sub-critical how, wetting/drying, culminating in the solution of a complete estuary problem. (C) 1998 Elsevier Science Ltd. All rights reserved.