Generation of Oscillating Grid Turbulence in a Rotating Tank and Flow Structure

One of the objectives of this study is to present devices of generating ideal oscillating grid turbulence in a rotating tank. Secondary flow which prevents the generation of ideal grid turbulence was suppressed by narrowing the space between the turbulence generation grid and the tank wall, modifying the support of the grid, and installing an inner cylinder. By means of the devices, the secondary flow disappears in the inner cylinder, and the turbulent flow becomes homogeneous in the stationary tank. Then, flow visualization experiments were conducted on the oscillating grid turbulence in the rotating tank. The flow structure is almost homogeneous in the vicinity of the grid, and the longitudinal vortex like structures appear on the rotating flow. The number of the longitudinal vortex structures increases and their shape become thin and straight with increasing the system rotation. The dye injection experiment also shows that the dye diffusion is suppressed by the rotation.