Chimera technique for transporting disturbances

Abstract

The Chimera technique for moving grids is used to take into account non-homogeneous unsteady onflow conditions in the simulation of aerodynamic flows. The method is applied to simulate the transport of a large-scale vortex by a mean velocity field over a large distance, where it finally interacts with an airfoil. The Chimera approach allows to resolve the vortex on a fine grid, whereas the unstructured background grid covering most of the computational domain can be much coarser. This method shows the same low numerical dissipation as a simulation on a globally fine grid. Several precursor tests are performed with a finite modified analytical Lamb-Oseen type vortex, to study the influence of spatial and temporal resolution and the employed numerical scheme. Then the interaction of an analytical vortex with a NACA0012 airfoil and with an ONERA-A airfoil near stall is studied. Finally a realistic vortex is generated by a ramping airfoil and is transported on a moving Chimera block and then interacts with a two-element airfoil, which allows to simulate a typical setup for a gust generator in aerodynamic facilities.