This study simulates the behavior of a jet issuing into a two-layer density-stratified fluid in a cylindrical tank and the resulting mixing phenomena. The upper and lower fluids are water and an aqueous solution of sodium chloride (NaCl), respectively, with the lower fluid issuing diagonally upward from a nozzle on the bottom of the tank. The angle between the centerline of the jet and the tank bottom is 60˚. The phenomena when the Reynolds number Re of the jet is 475, 1426, and 2614 are simulated. The mass concentration of the aqueous solution of NaCl is 0.02. The simulation successfully grasps the jet behavior and the resulting mixing, which agree with the authors' experimental results at the corresponding Re value. The secondary flows that appear in the horizontal cross-sections consist of a pair of vortices and flows along the tank wall. The secondary flow at the density interface represents the intrusion of an internal density current, which gives rise to mixing along the interface.

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Jet flow issued into two-layer density-stratified fluid in a cylindrical tank is numerically simulated. Vortex in cell (VIC) method combined with an Immersed Boundary (IB) method, which is presented by the current authors, is applied to the simulation. The upper and lower fluids are water and a NaCl-water solution, respectively, and the lower fluid is issued vertically upward from a nozzle on the bottom of the tank. The Reynolds number Re defined by the jet velocity and the nozzle diameter ranges from 95 to 1188, and the mass concentration of the NaCl-water solution C0 is set at 0 and 0.02. The simulation highlights that the jet behavior relative to the density interface and the resultant mixing phenomena depend on Re. Such simulated results are confirmed to agree well with the experimentally visualized ones, demonstrating the validity of the present simulation method.