Book Description

The new technique of Laser Induced Photochemical Anemometry (LIPA) has been developed to enable measurement of the evolution of coherent structures involved in the turbulent production process. Results are reported showing the measurement of the streamwise and transverse vorticity component and the strain rate as well as the Reynolds stresses at large numbers of points in a chosen plane. Calibration depends only on a time and a length scale. Comparison of measurements with the exact solution in a Stokes' layer indicates that the technique's accuracy can be predicted by classical error analysis and that it is comparable or better than that achievable with the best single point probe techniques. The results show the relative importance of streaks, pockets and hairpins that are generated in the vortex ring/wall simulation of the turbulence production process. Keywords: Turbulence; Boundary layer; Flow visualization. (mjm).