Two and Three-Dimensional Simulation of Sound Generated by Flow Around a Circular Cylinder

Abstract

The objective of this paper is to calculate the far-field sound generated from low mach number flow around a two-dimensional and three-dimensional circular cylinder in the subcritical regime using the Lighthill acoustic analogy. For the two-dimensional case, the timedependent incompressible flow is predicted using unsteady Reynolds-averaged NavierStokes models. For the three-dimensional case, the flow was obtained by solving the filtered Navier-Stokes equations of the Large Eddy Simulation model. As a benchmark, a flow-field with a Reynolds number of 90,000 is employed. The obtained numerical results such as Strouhal number, fluctuating lift and mean drag are compared with experiments. The computed unsteady pressure fluctuations on the cylinder wall are used as a sound source for the acoustic solver. Comparison between the two-dimensional numerical results and the experiment shows that computed acoustic field overpredict the noise amplitude; however, good agreement is obtained if an appropriate correlation length is taken into account. The sound measurements obtained by Revell et al. were carried out with a much longer span cylinder length when compared to the span used for the three-dimensional LES simulations. Therefore, the far-field sound is estimated by two correction methods proposed, respectively, by Kato et al. and Seo & Moon. The aerodynamic and acoustic results obtained by the threedimensional approach agree favorably well with the corresponding experimental data.