Effects of ambient viscosity on the entrainment and dynamics of a buoyant jet

In this paper we present results on the behavior of a turbulent, negatively buoyant jet in an ambient fluid having a higher viscosity than the jet fluid. Our experimental results indicate that the turbulent jet undergoes a reverse transition. Large scale eddies at the interface are suppressed, and the observed entrainment rate also reduces dramatically for the jet in a higher-viscosity medium. We also present results from numerical simulations, using vortex methods with a viscous diffusion scheme, to corroborate the results from our experiments.