Development of a structured overset Navier–Stokes solver with a moving grid and full multigrid method

Abstract

An unsteady Reynolds averaged Navier–Stokes solver with a structured overset grid method has been developed. Velocity–pressure coupling is achieved using an artificial compressibility approach, spatial discretization is based on a finite-volume method, and convective fluxes are evaluated by a third-order upwind scheme based on flux-difference splitting. Body motions are considered using the grid deformation technique and grid velocities in the convective term. Viscous fluxes are evaluated via second-order centered differencing. The full multigrid (FMG) method is applied to obtain fast convergence. The cell flag on a coarse grid level is determined using the cell flag on a fine grid level. In the coarse grid-level calculations at the FMG stage, the data are interpolated until the finest grid level is achieved at an overset update interval. Then, the data are updated based on the overset relations at the finest grid level and then transferred to a coarser grid level. For free surface treatments, a single-phase localized level-set method is employed. The computations for flows around a hull form, including an unsteady simulation with regular waves, are demonstrated.