2011 年 6 巻 4 号 p. 598-613
The flow and temperature/concentration fields in the mixing channel have complex three-dimensional and unsteady natures that are accompanied by flow separations and reattachments, longitudinal vortices, and large-scale velocity fluctuations. In this paper, detailed experimental results are presented on turbulent flow and mixing characteristics in a counter-flow type T-junction. The test fluid is water, and a fluorescence tracer is dissolved into the main-channel flow. The velocity and concentration fields are measured by PIV and PLIF with high temporal resolutions. At first, the three-dimensional structures of the velocity and concentration fields and the distributions of the turbulent mass fluxes that are dominant in the mixing process of two fluids with different concentrations are addressed. Then, the POD analyses are applied to the fluctuating velocity and concentration fields to extract their dominant structures. Based on the results of the POD, the turbulent mass transport process between two flows is examined.