Wavelet investigation of coherent structures behind permeable rib

Abstract

The stereo particle image velocimetry (PIV) technique has been used for the study of the turbulent flow behind surface mounted permeable ribs. The opening inside the rib termed here as slit and an obstruction within the slit known as splitter has been implemented to modify the vortical structures. The coherent structures have been studied using different vortex identification schemes i.e. vorticity, eigen value and the invariant of the velocity gradient tensor. The wavelet transform has been applied to the velocity and coherent structures identifiers field. It is observed that the wavelet transform is a successful tool to improve the signal to noise ratio during the vortex identification, remove the outliers due to PIV processing and determination of the large scale coherent flow field.