THE CHARACTER OF THE TURBULENT WALL PRESSURE SPECTRUM AT SUBCONVECTIVE WAVE-NUMBERS AND A SUGGESTED COMPREHENSIVE MODEL

The likely character of the wavevector-frequency spectrum of turbulent wall pressure on a smooth rigid plane is reexamined. Also, modeling is extended, for low Mach numbers, to the acoustic wavenumber domain. From the relation of the wavevector-frequency amplitude of wall pressure to amplitudes of fluctuating vorticity-related velocity products (Reynolds stresses) regarded as its sources, the dependence of the wall-pressure spectrum at subconvective wavenumbers is seen to depend essentially on the rate of decrease of the source cross-spectra with wall distance (y) and on the identity of the wavenumber coefficient (e. g. , omega / upsilon * or delta ** minus **1) that scales this profile. A model wall-pressure spectrum proposed earlier is generalized with respect to this rate of decrease and found to permit a range of possible dependences between K**0 and K**2 in that part of the subconvective domain where K APP GRTH delta ** minus **1. A comprehensive trial model for the wall-pressure spectrum based on source models yielding this character is proposed and viewed as potentially satisfactory in all wavenumber domains from the acoustic to the convective. For omega / c APP 1STH K APP 1STH delta ** minus **1, it varies as K**2, as follows for any source-spectral profile that decreases at least as ( delta /y)**4 for y APP GRTH delta , and accords with the Phillips-Kraichnan theorem.