Large Eddy Simulation of Turbulent Mixing : 3rd Report, The Case of Initial Random Fluctuations

Abstract

The aim of this study is a clarification of the spanwise and streamwise coherent vortical structures with initial random fluctuations in the temporally growing turbulent shear flows. To achieve this purpose, large eddy simulation of a turbulent shear flow was conducted. As an initial condition, random velocity fluctuations were superposed on the mean velocity profile, and 17 cases having different random fluctuations were calculated. From the calculated results, the following conclusions were obtained. (1) In spite of the existence of initial random fluctuations, spanwise and streamwise coherent structures can be observed. (2) The temporal development of the momentum thickness with initial random fluctuations does not show the lump which is observed in the case of periodic excitation.