Volume fraction instability in an oscillating non-Brownian iso-dense suspension

ROHT Y. L.; GAUTHIER G.; HULIN, J-P.; SALIN D.; CHERTCOFF, R.; AURADOU, H.; IPPOLITO, I; VIDALES A.M

Conferencia; Powder & Grains 2017; 2017

The instability of an iso-dense non-Brownian suspension of polystyrene beads of diameter 40 mdispersed in a water-glycerol mixture submitted to a periodic square wave oscillating flow in a Hele-Shaw cellis studied experimentally. The instability gives rise to stationary bead concentration waves transverse to theflow. It has been observed for average particle volume fractions between 0.25 and 0.4, for periods of the squarewave flow variation between 0:4 and 10 s and in finite intervals of the amplitude of the fluid displacement. Thestudy shows that the wavelength increases roughly linearly with the amplitude of the oscillatory flow; on theother hand, is independent of the particle concentration and of the period of oscillation of the flow althoughthe minimum threshold amplitude for observing the instability increases with the period.