Grid Convergence Study for Detached-Eddy Simulation of Flow over Rod-Airfoil Configuration Using OpenFOAM

A rod-airfoil is a benchmark configuration for simulating Airfoil-Turbulence Interaction Noise (ATIN). The numerical simulation is modelled using unsteady Detached Eddy Simulation (DES). The grid refinement involves two stages of assessments. The first compares the sensitivity of two reasonable estimated cells to the flow behaviours of the case. Based on the finding from the first stage, further grid refinement is proceed in stage two. In stage two, a minimum of three different grid resolutions are considered; the fine, medium and coarse grids in order to investigate the grid independency. Richardson extrapolation and Grid Convergence Index (GCI) are introduced to quantitatively evaluate the grid independency. Based on the results between those three different grids, a monotonic convergence criterion has been achieved. The reduction in GCI value indicates that the grid convergence error has been significantly reduced, in which the fine grid has a GCI value is around less than 0.5%. (paper)