SIMULATION OF CURVED OPEN-CHANNEL FLOWS BY 3D HYDRODYNAMIC MODEL

A mathematical model of three-dimensional (3D) free surface flows has been applied to simulate the curved channel flows and mass transport. In the horizontal plane, a channel-fitted curvilinear coordinate syste m is used, whereas in the vertical plane, the sigma-transformation is adopted to track the free surface and variable bed topography. To redu ce the numerical diffusion, the second-order upwind scheme of Roe is i ncorporated to discretize the convection terms. The standard k-epsilon model has been modified to take account of some anisotropic effects a ppearing in shallow curved channels, i.e., streamline curvature and th e damping effects of free surface and solid walls. The governing equat ions are solved in a collocated grid system by a fractional three-step implicit algorithm. Two test cases from curved flumes have been studi ed: (1) A 270 degrees channel bend with a sloped outer bank; and (2) a meandering channel with mass transport. The results are compared with the available data, which shows generally good agreement.