Non-overlapping Domain Decomposition for Modeling Essentially Unsteady Near-wall Turbulent Flows

In near-wall turbulence modeling it is necessary to resolve a thin boundary layer containing high gradients of the solution. An accurate enough resolution of such a layer can take most of the computational time. The situation becomes even worse for unsteady problems. To avoid time-consuming computations,
in the present paper a new approach is developed, which is based on a non-overlapping domain decomposition. The boundary condition of Robin type at the
interface boundary between domains is constructed by transferring the original boundary condition from the wall. For the first time, recently developed unsteady interface boundary conditions of Robin type are used for the unsteady Reynolds Averaged Navier-Stokes equations. The interface boundary conditions contain a memory term which takes into account the nonlocal effect in time to be taken into account for essential unsteady problems. In the case of stationary solutions the new approach automatically reduces to the technique earlier developed for the steady problems. The considered test cases demonstrate that the effect of the memory term can be significant for the accuracy of the near-wall
domain decomposition. The criteria for importance of the memory term in the interface boundary condition are formulated and confirmed for turbulent flows.