Large Eddy and Detached Eddy Simulations for Broadband Noise Prediction in Complex Geometries

Abstract

This paper deals with the specific issues of implementing a Large Eddy Simulation (LES) module in an unstructured solver, tailored to broadband noise analysis in turbomachinery. Four Sub-Grid-Scale (SGS) models have been introduced, focusing attention on complex geometries and the peculiarities of the unstructured implementation. For these reasons a two-dimensional extension of the LES solver has been developed and implemented. It should allow an easier approach to a proper LES solution, especially when dealing with geometries of high complexity. The problem of limiting the commutative error when using an implicit filter and unstructured grids has also been addressed. An appropriate filter size function has been introduced and a specific test has been performed in order to tune the parameters of this function. Investigation of the interaction between numerical diffusion and subgrid scale terms has also been carried out.