A hybrid LES/CAA method applied to jet noise prediction

Abstract

A new strategy regarding the simulation of sound generation and propagation is presented in this paper. A domain decomposition approach is used for the simulation of an aeroacoustic problem. The basic concept is to combi ne adapted numerical methods, equations, grids and even time steps for a greater efficiency. This aeroacoustic coupling is based on the splitting into noise sources generatio n and acoustic propagation in separate physical domains. In the case of turbulent flows, t he acoustic sources are often confined in a small part of the flow field. The key idea of the p resent work is to limit, as much as possible, the CFD domain to the noise generation computed with a LES and to accurately propagate the acoustic waves with a CAA solver. Generally, su ch a reduction of the CFD domain requires to couple the CFD and CAA computations with a coupling boundary located within the turbulent flow. In the present paper, this spli tting method is applied to a hot jet simulation. A LES based on the resolution of the Navier-Stokes equations with a Finite Volume Method on structured mesh is used to generate the acoustic sources, while an acoustic solver based on the resolution of Euler eq uations with a Nodal Discontinuous Galerkin Method on unstructured mesh propagates the acoustic waves. As a first step towards a full coupling, the present study deals wi th a “one way” coupling from LES to CAA.