Aeroacoustic source term computation based on radial basis functions

Abstract

SUMMARY In low Mach number aeroacoustics, the known disparity of length scales makes it possible to apply well‐suited simulation models using different meshes for flow and acoustics. The workflow of these hybrid methodologies include performing an unsteady flow simulation, computing the acoustic sources, and simulating the acoustic field. Therefore, hybrid methods seek for robust and flexible procedures, providing a conservative mesh to mesh interpolation of the sources while ensuring high computational efficiency. We propose a highly specialized radial basis function interpolation for the challenges during hybrid simulations. First, the computationally efficient local radial basis function interpolation in conjunction with a connectivity‐based neighbor search technique is presented. Second, we discuss the computation of spatial derivatives based on radial basis functions. These derivatives are computed in a local‐global approach, using a Gaussian kernel on local point stencils. Third, radial basis function interpolation and derivatives are used to compute complex aeroacoustic source terms. These ingredients are necessary to provide flexible source term calculations that robustly connect flow and acoustics. Finally, the capabilities of the presented approach are shown in a numerical experiment with a co‐rotating vortex pair.

Aeroacoustic wave equation based on Pierce's operator applied to the sound generated by a mixing layer

“…Regarding best practice for hybrid aeroacoustics source computations for finite element method [16,17], the right-hand sided of (1) and (2) were computed on the flow lattice and conservatively integrated to the finite element mesh [18,19]. The conservative integration by the cell-centered method was benchmarked by the superior cut-volume cell method with a negligible error of 0.1%.…”

Flexible Discretization for Computational Aeroacoustics

“…with u i the i-th component of the incopressible flow velocity. This source term is evaluated at the CFD mesh and then conservatively interpolated to the acoustic grid [12] With the given geometrical and physical setup a few test cases are defined in order to evaluate the sensitivity of the edge tone configuration to different grid resolutions.…”

Simulationen von Strömungsakustik in rotierenden Bauteilen zur Entwicklung von Antriebskonzepten der Autos der Zukunft

“…Dies ist notwendig, weil die nachfolgende Akustiksimulation auf der knotenbasierten Finite Elemente Methode [2] beruht. Für die Interpolation wird das Datenverarbeitungstool [3] von openCFS [14] verwendet.…”