TY - JOUR

T1 - Concurrent finite element simulation of quadrupolar and dipolar flow noise in low Mach number aeroacoustics

AU - Guasch, Oriol

AU - Pont, Arnau

AU - Baiges, Joan

AU - Codina, Ramon

N1 - Funding Information:
This work is supported by EU-FET grant EUNISON 308874. The second author would like also to acknowledge the Generalitat de Catalunya (SUR/ECO) for the predoctoral FI Grant no. 2015 FI-B 00227 , and the fourth author acknowledges the support received from the ICREA Acadèmia Program, from the Catalan Government. The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the Red Española de Supercomputación (RES-BSC) as well as the KTH (Kungliga Tekniska Högskolan) supercomputing center.
Publisher Copyright:
© 2016 Elsevier Ltd.

PY - 2016/7/15

Y1 - 2016/7/15

N2 - The computation of flow-induced noise at low Mach numbers usually relies on a two-step hybrid methodolgy. In the first step, an incompressible fluid dynamics simulation (CFD) is performed and an acoustic source term is derived from it. The latter becomes the inhomogeneous term for an acoustic wave equation, which is solved in the second step, often resorting to boundary integral formulations. In the presence of rigid bodies, Curle's acoustic analogy is probably the most extended approach. It has been shown that Curle's boundary dipolar noise contribution does in fact correspond to the diffraction of the quadrupolar aerodynamic noise generated by the flow past the rigid body. In this work, advantage is taken from this fact to propose an alternative computational methodology to get the individual quadrupolar and dipolar contributions to the total acoustic pressure. For any linear acoustic wave operator, the unknown acoustic pressure can be split into its incident and diffracted components and be computed simultaneously to the incompressible flow field, in a single finite element computational run. This circumvents the problem found in Curle's analogy of needing the total pressure at the body's boundary, which includes the acoustic pressure fluctuations. The latter cannot be obtained from an incompressible CFD simulation. The proposed unified strategy could be beneficial for a large variety problems such as those involving noise generated from duct terminations, or those related with the simulation of fricatives in numerical voice production, among many others.

AB - The computation of flow-induced noise at low Mach numbers usually relies on a two-step hybrid methodolgy. In the first step, an incompressible fluid dynamics simulation (CFD) is performed and an acoustic source term is derived from it. The latter becomes the inhomogeneous term for an acoustic wave equation, which is solved in the second step, often resorting to boundary integral formulations. In the presence of rigid bodies, Curle's acoustic analogy is probably the most extended approach. It has been shown that Curle's boundary dipolar noise contribution does in fact correspond to the diffraction of the quadrupolar aerodynamic noise generated by the flow past the rigid body. In this work, advantage is taken from this fact to propose an alternative computational methodology to get the individual quadrupolar and dipolar contributions to the total acoustic pressure. For any linear acoustic wave operator, the unknown acoustic pressure can be split into its incident and diffracted components and be computed simultaneously to the incompressible flow field, in a single finite element computational run. This circumvents the problem found in Curle's analogy of needing the total pressure at the body's boundary, which includes the acoustic pressure fluctuations. The latter cannot be obtained from an incompressible CFD simulation. The proposed unified strategy could be beneficial for a large variety problems such as those involving noise generated from duct terminations, or those related with the simulation of fricatives in numerical voice production, among many others.

KW - Computational aeroacoustics

KW - Diffraction

KW - Dipolar noise

KW - Flow noise

KW - Quadrupolar noise

UR - http://www.scopus.com/inward/record.url?scp=84966393377&partnerID=8YFLogxK

U2 - 10.1016/j.compfluid.2016.04.030

DO - 10.1016/j.compfluid.2016.04.030

M3 - Article

AN - SCOPUS:84966393377

SN - 0045-7930

VL - 133

SP - 129

EP - 139

JO - Computers and Fluids

JF - Computers and Fluids

ER -