Linear oscillations of constrained drops, bubbles, and plane liquid surfaces

Andrea Prosperetti

This paper demonstrates a method of analysis for shape oscillations in which a constraint prevents use of the standard approaches. The new method of analysis is demonstrated on 5 systems including a constrained drop, gravity-capillary waves on a plane liquid surface, and a simple instance of the Rayleigh-Taylor instability.

Phys. Fluids 24, 032109 (2012)

Cross-waves induced by the vertical oscillation of a fully immersed vertical plate

Frédéric Moisy, Guy-Jean Michon, Marc Rabaud, and Eric Sultan

The authors investigate the parametric instability leading to the generation of cross-waves excited by a fully immersed wavemaker. Their results suggest that the resonance responsible for the growth of the cross-wave may be simply described by a three-wave interaction mechanism, in which the oscillating flow above the wavemaker is modeled by a pseudo-third wavevector.

Phys. Fluids 24 , 022110 (2012)

Rheological measurements of large particles in high shear rate flows

Erin Koos, Esperanza Linares-Guerrero, Melany L. Hunt, and Christopher E. Brennen

The authors explore the rheology of an inertial suspension under conditions in which collisions may become important. The authors use a Couette concentric cylinder rheometer designed to reduce the effect of Taylor vortices to measure the torque and shear stress on mixtures of neutrally and slightly non-neutrally buoyant particles in a Newtonian fluid. The results are presented for Reynolds numbers between 20 and 800 and Stokes numbers from 3 to 90. The presentation also includes measurements for both smooth and rough walls and examines the effect of wall slip in determining the relative viscosities of the suspensions.

Phys. Fluids 24, 013302 (2012)

Developed quantum turbulence and its decay

L. Skrbek and K. R. Sreenivasan

The authors attempt to review the correspondence between classical and quantum turbulence with particular attention to the conceptually simplest case of zero temperature limit where quantum turbulence consists of a tangle of quantized vortex line and represents a simple prototype of turbulence. At finite temperature, the authors focus at the level of two-fluid description of the superfluid state - consisting of a normal viscous fluid and a frictionless superfluid - and review much of the available knowledge on quantum turbulence in liquid helium (both He II and ³He-B). The authors consider counterflows in which the normal and superfluid components flow against each other, as well as co-flows in which the direction of the two fluids is the same.

Phys. Fluids 24, 011301 (2012)