Design and analysis of a new filter for LES and DES

Spatial filters have been rigorously analyzed here for stabilization and dispersion relation preservation properties using spectral-matrix theory. Traditional LES faces problems of instability, aliasing and additional complexity of SGS modeling. Here, an alternative is proposed where unfiltered governing equation is solved, followed by spatial upwind filtering, without requiring any SGS models. This filter retains the resolution of high accuracy methods and removes energy, like the action of hyper-viscosity used in spectral methods. As examples, solutions for (a) accelerated flow past a NACA-0015 airfoil held normal to the flow and (b) transitional flow past a NLF airfoil, have been reported.