Numerical solution of tidal currents at marine waterways using wet and dry technique on Galerkin finite volume algorithm

Abstract

In the present paper the Galerkin finite volume method (FVM) is developed for solution of unsteady; two dimensional shallow water flow equations on unstructured triangular meshes. The numerical model considered two types of wetting and drying process which is an essential technique for modelling the tidal flow in the coastal zones with arbitrary topography. The use of triangular cells facilitates local refinement in the areas with considerable bed elevation variations. Hydrostatic pressure distribution was assumed and the effects of bed slope and friction are considered in two equations of motion. In order to damp out the unwanted numerical oscillations and reduction of instability of the numerical model and its stability during model running, the artificial viscosity was added to the formulation. The quality of the solution result and the accuracy of the applied model is assessed by comparison between numerical results and reported data in the literature for flow in a channel with spur dike which showed an average error of 6% with the experiment data. In addition to assure model accuracy and capability in wetting and drying situations, the current model was examined on an inclined bed with flooding and dewatering process. Numerical Result analysis showed that the second applied wet/dry technique enhanced outcomes from 5% average error to 3%. As a real world case study, Qeshm canal is considered in this study. In the Qeshm canal (located in the east part of the Persian Gulf) the flow pattern is formed by tidal currents via two open boundaries in the west and east ends. Besides, the computed water elevation and velocity at Kaveh port are compared with the available measurements for a period of time, in which the computed water elevation is much closer to the observed data rather than the computed velocity.