Convection of a colloidal suspension in a Hele-Shaw cell.

The results of a theoretical study are presented dealing with convective heat and mass transfer in a colloidal suspension through a Hele-Shaw cell heated from below. The numerical analysis, based on a multi-component model, reveals that for a certain range of parameter values the dynamical regimes of travelling waves as well as oscillatory fingering formation are stable. The bifurcation phenomena and nonlinear evolution of spatiotemporal patterns that develop in the colloid suspension are modeled and discussed, paying special attention to the combined effects of gravity sedimentation, thermal diffusion with positive separation ratio and convection.

Traveling-wave convection in a binary fluid mixture under high-frequency vertical vibrations.

The convective stability thresholds and nonlinear spatiotemporal evolution of convective rolls in a plane horizontal layer subject to steady gravity and high-frequency transversal vibration are numerically investigated considering a laterally periodic convective cell with rigid, impermeable horizontal boundaries. Simulations are performed for parameters adapted to laboratory experiments with an ethanol-water mixture with negative Soret coupling between temperature and concentration gradients. The characteristics of the wave and steady patterns are investigated depending on heat and vibration intensities.

Traveling-wave convection in colloids stratified by gravity.

Thresholds of convection excitation and nonlinear convective flow patterns in a horizontal colloidal-mixture layer heated from below are investigated. We take into consideration the fact that, provided the barometric stratification has been reached prior to imposing the temperature gradient, only oscillatory disturbances develop. The influence of separation ratio, sedimentation length, and Prandtl number on the thresholds of oscillatory convection is studied.