AN UNSTRUCTURED FINITE-VOLUME ALGORITHM FOR PREDICTING FLOW IN RIVERSAND ESTUARIES

A numerical algorithm is presented for the solution of geometrically c hallenging two-dimensional river and estuary flows, based on an adapti ve triangular tessellation of the how domains of interest. The governi ng, shallow water, equations are discretised using st finite volume ap proach embodying variable step time integrators, to yield a method tha t is second order accurate in both space and time. An approximate Riem ann solver is used to determine flow directionality in conjunction wit h an effective means of dealing with wetting and drying at the boundar ies. The approach is capable of handling complex flow domains and yiel ding solutions for which errors are controlled automatically by the us e of spatial re-gridding and time stepping based on local error estima tes. Its range of applicability is demonstrated through considering se veral problems involving super/sub-critical how, wetting/drying, culmi nating in the solution of a complete estuary problem. (C) 1998 Elsevie r Science Ltd. All rights reserved.