SIMULATION OF PARTICLE SEGREGATION IN A BIDISPERSE SUSPENSION

International audienceWe have developed a numerical simulation including many body hydrodynamic interactions which allows to reproduce particle's migration in a monodisperse or a bidisperse suspension placed in a two dimensional Couette flow. The concentration profiles obtained by numerical simulation have been compared to the predictions of models based on the ideas of Leighton and Acrivos. For monodisperse suspensions it appears that taking into account the flux due to the curvature of streamlines well improve the agreement of the model with the numerical simulation. In the bidisperse case for a ratio of sizes a1/a2=0.2, we observe a strong segregation with the large particles going towards the lower shear rate gradients. Our model for bidisperse suspensions fairly well predicts this behaviour without the addition of others parameters. The comparison between numerical simulations and the bidisperse model will be worked out for different size ratios and volume fractions. Concerning the phase separation in bidisperse 2D suspension under simple shear rate, we perform now a theoretical interpretation including diffusion coefficients in order to predict the appearance of stripes depending on the radius ratio and concentration of the spheres