An Investigation of the Flow around a Permeable Three-dimensional Body on the Plate(3rd Report, The Variation of Velocity Profile and the Vortex Shedding)

Measurements were made of the velocity vectors and the power spectra around the permeable wall cube placed in the turbulent boundary layer. The aim was to investigate the effects of the open area ratio of cube and the boundary layer characteristics on both the mean velocity field and the aspects of the vortex-shedding. The range of open area ratio for which the separation bubble attaches to the permeable wall cube, was smaller in the case of the thin boundary layer thickness than the thick one. The research of the peak spectrum at a prominent frequency, its value in the power spectra and the flow visualization using the smoke wire method, clarified the structure of the vortex shedding from the permeable wall cube. The vortex-shedding frequency was independent of the value of open area ratio for each boundary layer, but the values of the power spectrum at the shedding frequency were different in the various positions around the cube.