A numerical technique for treating complex geometries in compressible staggered cartesian code

In the present report, within the program agreement MSE-ENEA, an efficient Immersed Volume Method (IVM) for the computation of compressible viscous flows with complex stationary geometries in a staggered non-uniform cartesian finite difference code (HeaRT code is presented). A background Cartesian mesh is generated for each staggered variable and a finite volume approach is adopted in the layer near the immersed boundaries by means of cut cell method. Accurate description of the real three-dimensional geometry inside the cut cell volume is preserved by means of triangulated surface description instead of approximating it by a plane. The overall accuracy of the base solver (2nd order in this article) is preserved by means of high order flux reconstruction in the cut cells. The Large Eddy Simulation (LES) solver is parallelized using domain decomposition and message passing interface. The robustness and accuracy of the method is proved simulating a laminar flow past a cube at Re=215, a turbulent flow past a sphere with a sting at Re=51500 and a turbulent premixed, stoichiometric CH4/Air bluff body flame at Re=3200, both adopting the LES approach.