密度界面に衝突する渦輪の数値シミュレーション

抄録

This study simulates the behavior of a vortex ring launched toward the interface of a two-layer density stratified fluid and the resulting mixing phenomena between the fluids. Initially, the density-stratified fluid is in a static condition in a tank. The upper and lower fluids are glycerol aqueous solution and an aqueous solution of potassium dihydrogen phosphate, respectively. The vortex ring with a diameter of 26.4 mm is launched vertically downward from the upper fluid region. It travels by the vertical motion toward the density interface. The Reynolds number, based on the circulation of the vortex ring, is 3500. The simulation conditions are parallel with an experimental work of one of the authors. The vortex in cell method, which was presented by the authors for flow simulations of two-layer density stratified fluid in a prior study, is used. The simulation favorably highlights the collision, deformation and penetration of the vortex ring at the density interface. It also successfully reveals the mixing between the upper and lower fluids induced by the motion of the vortex ring. These simulated results are discussed by comparing with the corresponding experimental ones.