ABSTRACT

A numerical method is developed for solving the unsteady Reynolds-averaged Navier-Stokes (URANS) and turbulence closure equations in complex, multi-connected, 3D geometries. The governing equations are solved with a second-order-accurate finite-volume, dual-time-stepping artificial compressibility approach. Arbitrarily complex geometries are handled using domain decomposition with overset (Chimera) grids. The method is applied to simulate turbulent flows in two three-dimensional configurations inspired by the geometry of real-life bridge foundations in natural rivers: a channel with four bottom-mounted rectangular piers and a channel with a corner-mounted rectangular block. Comparisons between the computed results and laboratory measurements and flow visualization experiments lead to the conclusion that even relatively simple turbulence closure models (such as the standard k−ε model with wall functions or the one-equation Spalart-Allmaras model) can simulate flows with large-scale coherent structures with reasonable accuracy.