Manipulation of the Growth Rate of a Variable Density, Spatially DevelopingMixing Layer via External Modulation

摘要

The evolution of a spatially-developing, incompressible, inviscid, variable-density, confined mixing layer is numerically simulated using the transpore element method. In this flow, vorticity is generated and destroyed by the baroclinic torque, while the density gradient changes according to the deformation imposed by the flow map. Results show that density variation affects the spreading rate of the layer, the phase speed of the instability waves and the convective velocity of the eddies, and alters the asymmetric entrainment patterns observed in a uniform-density flow. The results are in agreement with experimental and analytical results which indicate that, at fixed velocity ratio, the spreading rate (convective speed of the eddies) increases (decreases) with increasing density ratio, and the entrainment patterns become biased towards the low-density side.