Prediction of turbulent flow in two-dimensional channel with turbulence promoters. 3rd report Improvement of large eddy simulation and formation of streaklines.

Abstract

Fully developed incompressible turbulent Flow in two-dimensional channel with turbulence promoters has been predicted numerically by large eddy simulation, Parameter C in Smagorinsky model can be assumed constant generally in the range of high Reynolds. In this paper, C is varied with SGS Reynolds number in low Reynolds number region and SGS eddy diffusivity near the solid boundary is considered as a function of the distance from the boundary, the velocity gradient and the molecular viscosity, There improvements of SGS eddy viscosity model and the boundary condition of SGS eddy diffusivity have little effects on the mean velocity distribution, but have a significant effect on distributions of turbulence and turbulent shear stress. Computed streaklines and Strouhal number of vortex shedding behind the turbulence promoter are compared with visual experiments. The Reynolds number in computation is set at 1.1 × 104 and 9000 grid are distributed.