A Conservative Solid-Gas Coupling Scheme with Overlapping Meshes for Combustion Simulation of Propellants with Voids

A conservative coupling scheme with overlapping meshes for the combustion simulation of propellants with voids is established. The two main ingredients of this scheme are the conservative calculation of fluxes of mass, momentum, energy, and species and the robust treatment of voids. Specifically, for the discrete flux calculation, firstly the solid-gas interfaces are captured by the level-set method and then sampling points are generated between the interfaces at consecutive time steps, and these points are used to ensure the conservation of these quantities up to each grid of the gas domain. For the second ingredient, the void before exposure is treated as "solid" with properties of the air. Once an exposure condition is met, the topological change of the void is realized by reinitializing the level set function inside and on the boundary of the void. Overall, the scheme is conservative and robust, which is validated with experimental results.