Soret driven convection in a colloidal solution heated from above at very large solutal Rayleigh number

Abstract

Convection in a colloidal suspension with a large negative separation ratio ψ is studied experimentally by heating from above. Shadowgraph observations at very large solutal Rayleigh numbers R ̃ are reported as a function of time. Fast relaxation oscillations are reported for the root mean square value of the shadowgraph intensity. While pure fluids exhibit a transition to turbulent convection for Rayleigh number R≃ 10 6, stable spoke-pattern planform with up and down columnar flows are observed up to R ̃≃ 1.9× 10 9. It is suggested that the surprising stability of the planform against turbulence is due to nonlinear focusing arising from the concentration dependence of the diffusion coefficient.

Roberto Cerbino

Professor of Experimental Soft Matter Physics

My research interests include Soft matter physics, living matter, cell biophysics and quantitative microscopy.