A High Order Overset Flux Reconstruction Method for Dynamic Moving Grids

Abstract

Overset meshes have a unique advantage in handling moving boundary problems as remeshing is often unnecessary. Recently, overset Cartesian and strand meshes were used successfully to compute complex flow over rotorcraft. Although it is quite straightforward to deploy high-order finite difference method on the Cartesian mesh, the near-body solver for the strand mesh is often limited to second order accuracy. In the present work of this dissertation, we develop a high-order FR/CPR solver, hpMusic, on both the near-body and background grids, and extend it to handle moving boundary problems. The solver is also extended to sliding meshes, which can be considered a special case of overset meshes. The use of sliding meshes can often simplify the treatment of moving boundary problems with simple translational and rotational motions. Two different approaches to handle the overset interfaces are evaluated for accuracy, efficiency and robustness. Accuracy studies are carried out and the designed order of accuracy is obtained for both inviscid and viscous flows. Steady and unsteady flow problems are solved on stationary overset meshes. The results agree well with those in the literature and from experiments. A turbine blade under the wake of moving cylinders is simulated using sliding meshes. The flow structures are compared with those without moving cylinders. The solver is then tested for moving overset meshes with a benchmark dynamic airfoil problem from the 4th International Workshop on High-Order CFD Methods. Hp-convergent results are obtained and compared with those from other groups. Finally flow over a hovering rotor is simulated to compare with experimental data. In this case, the present high-order solver is capable of generating and propagating tip vortices with high resolution. Good agreement is achieved with experimental data in tip vortex core size, location, and the swirl velocity at 3rd order accuracy.