A Framework for Permeable Boundary Conditions in SPH: Inlet, Outlet, Periodicity

We present a novel method for implementing sub-critical permeable boundary conditions into the Smoothed Particle Hydrodynamics (SPH) method. Inlet and outlet boundary conditions (BCs) are realized by extending the inflow and outflow region by a buffer zone. Dirichlet and Neumann boundaries are achieved by prescribing the properties of the buffer particles. Periodic boundary conditions are achieved by creating spatially shifted particle copies. Up to three translational periodic conditions and one rotational periodic condition can be applied. By using special marker particles, the boundary faces can be arbitrarily shaped and located. The computational framework is compatible with domain decomposition based parallelization. The presented boundary treatment enables the simulation of air assisted fuel atomizers typically used in aircraft engines.