Computational framework for coupling compressible and low Mach number codes

A hybrid multicode computational method is developed that allows combining compressible and low Mach number codes into a single computational solver. The proposed methodology can be used for integrated simulations of multicomponent engineering problems. The unsteady coupling between the two codes is performed via exchanging time-dependent state information through the interfaces using overlapping meshes. The proposed coupling procedure is validated on laminar steady and unsteady test problems. Both constant-density and variable-density regimes of the low Mach number code are investigated. Results of the test cases performed in frameworks of one-way coupling and two-way coupling are documented. Several methods of implementation of interface conditions for the compressible code are compared by looking at the levels of dilatation, as well as numerical errors. The injection method (when all the variables are simply transformed from one code to another through an interpolation procedure) is chosen for its superior stability, accuracy, and simplicity of implementation. Numerical results for the coupled calculations obtained with the injection method show good agreement with both standalone calculations and analytical solutions.