Variable-density effects in incompressible non-buoyant shear-driven turbulent mixing layers

Buoyant turbulent mixing in shear layers

Buoyancy effects in unstably stratified mixing layers express themselves through gravity currents of heavy fluid which propagate in an ambient lighter fluid. These currents are encountered in numerous geophysical flows, industrial safety and environmental protection issues [1] . During transition to turbulence a strong distortion of the separating interface between regions containing ‘heavy’ or...

On density effects and large structure in turbulent mixing layers

Plane turbulent mixing between two streams of different gases (especially nitrogen and helium) was studied in a novel apparatus. Spark shadow pictures showed that, for all ratios of densities in the two streams, the mixing layer is dominated by large coherent structures. High-speed movies showed that these convect at nearly constant speed, and increase their size and spacing discontinuously by ...

Acceleration-driven variable- density turbulent flow

We discuss turbulent dynamics and mixing of a variable-density flow subject to a uniformacceleration field. The flow resulting from initial misalignments of pressure and density gradients is investigated for small to large density ratios, with evidence that the smalldensity ratio flow is described by the Boussinesq approximation. A new shear-layer growth rate is reported. Spectra collapse when ...

Analysis of Inertial and Buoyant E ects in Turbulent Fluid Mixing Layers

The rate of expansion of a planar, incompressible two-uid mixing layer subject to a time-dependent acceleration g(t) has been accurately measured by Dimonte and Schneider for several diierent g(t) and a wide range of density ratio. Their measurements can be replicated by solving a phenomenological force law for the interpenetrating bubbles and spikes that comprise these mixing layers. The coeec...

Effect of Merging Angle on Turbulent Mixing Layers