Hybrid computational aero-acoustic (CAA) solution schemes rely on the knowledge of a scattering function known as a Green's function to propagate source fluctuations to the far-field. Presently, these schemes are restricted to relatively simple geometries. We present here a computational method for evaluating Green's functions within more geometrically complex regions, as a means of extending the versatility of existing hybrid schemes. The direct collocation implementation of the Boundary Element Method used in truncated, semi-infinite domains, introduces additional unknowns on the boundary. In this paper we develop a modified boundary element formulation to efficiently incorporate approximate Non-Reflecting Boundary Conditions for an arbitrary number of truncation boundaries. The boundary condition is based on the Dirichlet-to-Neumann mapping operator. Results are compared to known analytical Green's functions for an infinite pipe as a means of validating the new code. The method achieves relative errors of less than 1% compared with the analytical solution for the highest mesh density tested. Execution time, known to be large for acoustic problems, is minimised through the use of multi-threading.
|Title of host publication||Proceedings of Internoise 2014|
|Publication status||Published - 2014|
|Event||Internoise 2014 - Melbourne, Australia|
Duration: 16 Nov 2014 → 19 Nov 2014
|Period||16/11/14 → 19/11/14|