Implementation of a stable high-order overset grid method for high-fidelity simulations

Abstract

The implementation of an overset grid method into a compressible in-house computational fluid dynamics solver is described. The framework employs a novel algorithm for the generation of the composite grid, i.e. to identify the discretisation, interpolation and non-physical points. This algorithm was designed to minimise and simplify the user input, while maintaining the flexibility to handle complex setups. An explicit fourth-order Lagrange interpolation scheme is used, so that the formal order of accuracy of the finite difference scheme used in the flow solver is matched. An instability linked to the possible presence of uncoupled numerical solutions on separate grids sharing the same physical location is discussed, and a modification of the composite grid generation algorithm that prevents this instability is introduced. The final overset grid method is validated with two test cases: the convection of an isentropic vortex and the Taylor-Green vortex.