Zhang H., Pan Y.

In this paper, a numerical simulation of flow-induced sound by the low Mach numbers, no pressure gradient, fully developed turbulent boundary layer on a smooth, rigid flat plate is presented based on the unsteady incompressible Navier-Stokes equations and Lighthill acoustic analogy. Large Eddy Simulation (LES) was used to investigate space-time flow field and the Smagorinsky sub-grid scale (SGS) model was introduced for turbulence model. The velocity and pressure fluctuations induced by turbulent shear flow were simulated numerically. Using Lighthill¡¯s acoustics analogy, the flow field simulated by LES was taken as near-field sound sources and radiated sound from turbulent boundary layer (TBL) was computed by Curle¡¯s integral formulation under the low-mach-number approximation. The radiated sound of dipole type, of quadrupole type, and of the sum of the two above were discussed. It predicts powerful dipole radiation as a result of the fluctuating stresses acting on the fluid by the solid boundary, in addition to the quadrupole sound caused by the unsteadiness of fluid itself. Comparing their power spectral densities, we concluded that in low Mach number, the wall shear stress (dipole type of source) was the dominant factor responsible for sound radiation from TBL. The results show that it is successful for using LES method to study radiated sound from turbulent boundary layer and wall pressure fluctuations field.