An experimental study was conducted to further our understanding about the fundamental physics of electrokinetic instability (EKI) and to explore the effectiveness to enhance fluid mixing inside a Y-shaped microchannel by manipulating convective EKI waves. The dependence of the critical voltage of applied static electric field to trig EKI to generate convective EKI waves on the conductivity rat...

Large quantities of methane hydrate are present in marine sediment. When methane hydrate is exposed or released to seawater, it dissolves in seawater or dissociates into methane gas and water. There was some confusion in the literature about the kinetics of these processes. It is critical to realize that dissolution and dissociation are two different processes. Dissolution is due to instability...

The effect of localized roughness on a Ma=4.8 boundary-layer and its instability is investigated by means of unsteady direct numerical simulations. The occurrence of special flow features, such as shocks, boundary-layer separation zones, streamwise vortices and streamwise streaks behind a three-dimensional square-shaped roughness element are discussed. In order to investigate the convective ins...

A combined experimental and numerical study of a Rayleigh-Bénard-Poiseuille air flow in a rectangular channel is presented. The aim of the present paper is to characterize a secondary instability, referred to as wavy instability and known to be a convective instability, with the objective to identify the best situation for an optimal homogenization of heat transfers in the system. A periodic me...

The magnetorotational instability (MRI) is thought to play a key role in the formation of stars and black holes by sustaining the turbulence in hydrodynamically stable Keplerian accretion disks. In previous experiments the MRI was observed in a liquid metal Taylor-Couette flow at moderate Reynolds numbers by applying a helical magnetic field. The observation of this helical MRI (HMRI) was inter...

Using a linear stability analysis and two and three-dimensional nonlinear simulations, we study the physics of buoyancy instabilities in a combined thermal and relativistic (cosmic ray) plasma, motivated by the application to clusters of galaxies. We argue that cosmic ray diffusion is likely to be slow compared to the buoyancy time on large length scales, so that cosmic rays are effectively adi...

Colloidal suspensions aging under gravity have long been known to spontaneously separate into layers. We demonstrate through flow visualization experiments that a lateral temperature gradient as small as 10 mKycm can be responsible for such stratification and that strata correspond to a stack of convection rolls. A linear stability analysis suggests that the onset of stratification results from...

We consider the solidi cation of a binary alloy in a mushy layer and analyse the linear stability of a quiescent state with speci c interest in identifying an oscillatory convective instability. We employ a near-eutectic approximation and consider the limit of large fareld temperature. These asymptotic limits allow us to examine the dynamics of the mushy layer in the form of small deviations fr...

2014 The effect of a horizontal magnetic field on the three-dimensional instabilities which occur in a Rayleigh-Bénard experiment with mercury is studied. When the magnetic field is parallel to the roll axis, the Busse oscillatory instability is inhibited, and the fluid motions become bidimensional. The high heat transport may be associated with an inertial convection mode. Tome 42 No 21 ler NO...