STRONGLY-COUPLED MULTIGRID METHOD FOR 3-D INCOMPRESSIBLE FLOWS USING NEAR-WALL TURBULENCE CLOSURES

An efficient artificial compressibility algorithm is developed for sol ving the three-dimensional Reynolds-averaged Navier-Stokes equations i n conjunction with the low-Reynolds number k-w turbulence model (Wilco x, 1994). Two second-order accurate central-differencing schemes, with scalar and matrix-valued artificial dissipation, respectively, and a third-order accurate flux-difference splitting upwind scheme are imple mented for discretizing the convective terms. The discrete equations a re integrated in time using a Runge-Kutta algorithm enhanced with loca l rime stepping, implicit residual smoothing, and V-cycle multigrid ac celeration with full- and semi-coarsening capabilities. Both loosely a nd strongly-coupled strategies for solving the turbulence closure equa tions are developed and their relative efficiency is evaluated Calcula tions are carried out for turbulent flow through a strongly-curved 180 deg pipe bend discretized with fine, highly-stretched and skewed mesh es. It is shown that the strongly-coupled multigrid algorithm, with se mi-coarsening in the transverse plane, is an efficient approach for si mulating flows of practical interest with advanced near-wall turbulenc e closures.