Penetration Depth of a Plunging Jet: From Microjets to Cascades.

When a liquid jet impacts a pool of the same liquid, a bubble cloud is generated below the surface: we address here the question of the vertical size of this bubble cloud. We have measured this size on experiments spanning a large range of scales, from 0.3 to 210 mm in jet diameter, and from 0.

Influence of Gas Turbulence on the Instability of an Air-Water Mixing Layer.

We present the first evidence of the direct influence of gas turbulence on the shear instability of a planar air-water mixing layer. We show with two different experiments that increasing the level of velocity fluctuations in the gas phase continuously increases the frequency of the instability, up to a doubling of frequency for the largest turbulence intensity investigated. A modified spatiotemporal stability analysis taking turbulence into account via a simple Reynolds stress closure provides the right trend and magnitude for this effect.

Influence of particles on the transition to turbulence in pipe flow.

We investigate by experiment the influence of suspended solids upon the transition to turbulence in pipe flow. The particles are monodisperse and neutrally buoyant with the liquid. The role of the particles on the transition depends upon both the volume fraction, phi, and particle size.