Boundary conditions and subgrid scale models for LES simulation of Internal Combustion Engines

The implementation and the combination of advanced boundary conditions and subgrid scale models for Large Eddy Simulations are presented. The goal is to perform reliable cold flow LES simulations in complex geometries, such as cylinder engines. In the paper, an inlet boundary condition for synthetic turbulence generation is combined with a fully non reflecting Navier Stokes Characteristic Boundary Condition (NSCBC) for the outlet and with the local Dynamic Smagorinsky subgrid scale model, that is not included in the official distribution of OpenFOAM. Validation of the models has been performed separately on two steady state flow benches: a backward facing step geometry [1] and a simple IC engine geometry with one axed central valve [2]. The code developed has been included into LibICE, a set of applications and libraries for multi-dimensional engine modeling based on the OpenFOAM technology.