せん断乱流場における混合現象のLagrange的シミュレーション

Abstract

This paper deals with the mixing phenomena in a main flow direction within a bounded turbulentshear flow in view of Lagrangian aspect.Data obtained by numerical simulations are analized through application of Taylor's classicturbulent diffusion theory by continuous movements: Main objectives are to disclose the relations ofLagrangian properties, such as Lagrangian auto-correlation coefficient, integral time scale and dis-persion coefficient with Eulerian Flow properties and also to obtain differences of these Lagrangianproperties between two and three dimensional turbulent shear flows.As results of this study, it is concluded that the auto-correlation coefficient in a three dimensionalturbulent shear flow is quite different from that in a two dimensional one, and that the lateral non-uniformity of velocities averaged in a vertical direction and the lateral turbulent intensity are mosteffective on the longitudinal mixing in three dimensional turbulent shear flows.