Empirical optimization of sponge layers for enhanced accuracy in simulations of compressible cavitation

A numerical method for implementing sponge layer boundary conditions in compressible cavitating flows using the homogeneous mixture approach has been validated, which can effectively absorb the non-physical boundary reflection. For that, a set of more robust formulations have been developed and integrated into the commercial numerical solver ANSYS Fluent®. A numerical assessment of their design tunable parameters, such as time step, sponge layer length, and sound speed, has been conducted for optimization. As a result, a novel non-dimensional coefficient combining these parameters has been introduced. Then, well-defined test cases, such as a 1D compressible cavitating Sod shock tube using the equation of state, a quasi-3D cavitation bubble collapse, and the cavitating flow behind a wedge employing a transport equation model have been used for validation. The results obtained with the optimized sponge layers are promising and they suggest that low reflection levels (