Development of a VOF Dynamic Solver in OpenFOAM: an Application to the Simulation of the Opening and Closure Events in High Pressure GDI Injectors

The simulation of the primary liquid atomization in industrial geometries of atomizers for Gasoline Direct Injection (GDI) requires to accurately resolve the gas/liquid interface and time-resolved turbulence modeling. A dynamic multiphase volume-of-fluid (VOF) dynamic solver has been implemented in the OpenFOAM ® technology to simulate flow cavitation during needle opening and closure events. The solver is based on the extension of an already existing multiphase two-fluid model; it makes use of ad-hoc implemented cavitation sub-models and, with respect to the solver available in the official distribution of OpenFOAM, it includes some novel features: it is coupled to an advanced fully-automatic parallel mesh motion solver supporting topological changes of the mesh, where dynamic addition and removal of cell layers is performed to simulate the prescribed motion of the injector needle; also, needle opening and closure events are simulated by performing dynamic detach/attach of one mesh region into multiple regions. In the fluid-dynamic solver, a pressure-correction equation to enforce continuity after topological changes in the pressure-velocity coupling algorithm of the segregated solver and to to favor the solver convergence without compromising the accuracy of the solution. The resulting solver supports cavitation sub-models as well as LES and hybrid RANS/LES models for turbulence. Code validation is performed against standard test cases available from the litterature and against experiments.