Boundary layer surface vorticity flux measurements at high Reynolds number

Under isothermal conditions vorticity enters a flow through a flux at the wall. If the walls are stationary, this flux is proportional to the pressure gradients in the plane of the surface. Wall vorticity flux measurements were acquired through the use of closely spaced microphones in arrays mounted flush with the surface. The measurements were acquired at $R_ {\theta} = O(10^6)$ under the near-neutral thermally stratified condition at the SLTEST site in Utah's west desert. Owing to the attributes of the flow at the SLTEST site, pressure measurements there are especially devoid of the noise sources found in wind tunnels. Through the use of a variety of microphones and microphone separations, the sensitivity of the measured vorticity flux is explored relative to the spatial and temporal resolution of the sensors. Spectra and pdfs of both the pressure and pressure gradients are presented. Comparisons of the normalized surface vorticity flux intensity are made with previous low $R_{\theta}$ laboratory based measurements.