The Overlapping Grid Technique for the Time Accurate Simulation of Rotorcraft Flows

This paper presents the implementation of the overlapping grid technique into DLR's structured flow solver FLOWer. The hole cutting procedure and the search methods are described. Trilinear interpolation is used to transfer flow data between grids. For data interpolation close to solid surfaces, a projection algorithm is applied which corrects discretization effects. The approach used to prescribe rigid body motions for unsteady flow simulations allows to relate the motion of any body to any other body. Unsteady simulations also require to consider the hole motion during the definition of the interpolation points. For the integration of forces on grids with mesh overlap on body surfaces a unique surface is generated. Background grids are created with a Cartesian grid generator, which allows for cubic and anisotropic cells. Several examples of applications demonstrate the generality of the implementation of the Chimera techniqu