Effects of Turbulence Made of Combination of Stretched and Unstretched Turbulence on Turbulent Diffusion

Abstract

The purpose of this study is to investigate the effect of turbulence properties on turbulent diffusion phenomena. Various turbulent flow fields mixed stretched and unstretched turbulence were made by changing the type of turbulence generator set in inlet and outlet positions of the contraction unit of a wind tunnel. As the result, it was found that the highest diffusion factor was in the case that turbulence generator was set in the inlet position of the contraction, namely, stretched turbulence only. This result means that stretched longitudinal vortex contributes greatly to turbulent diffusion and longitudinal vortex is broken down by the turbulence generator when it is set in the outlet position of the contraction.