Computational study on the structure of the attached eddies in a turbulent boundary layer

Abstract

A computational study on the geometric and kinematic characteristics of the organized structures in a turbulent boundary layer is presented in this thesis. It contains primarily the explanations of various aspects of two-point space-time correlation measurements in a turbulent boundary layer done by previous researchers in light of the attached eddy model of turbulence. For a successful prediction of turbulence statistics using the attached eddy model, the detailed knowledge of eddy geometry and their kinematic behavior is very vital. Unfortunately, as off today very little is known about it. The numerical results show, a good degree of qualitative agreement with those found by experimental researchers. It appears that for a better quantitative agreement between the two, additional structures, as well as further modifications of the representative eddy geometry are necessary. This indicates a complicated eddy structure that needs rather complicated mathematical treatment requiring time intensive computer simulation. However, the effect of the change in the number of length scales in eddy hierarchy range was found to be negligible when the number is over 128.