Speaker: Abdessamad Nait Ouhra

Date: Thursday 13th of January 2022, 1:15 pm.


The rheology and dynamics of red blood cells (RBCs) under confined flows, are studied in the Stokes limit. We numerically investigated the lateral migration of a suspended vesicle (a model of (RBCs)) in a bounded shear flow. We explore the relevant dimensionless parameters to study the dynamics and rheology of a vesicle as a function of the viscosity contrast λ = ηin/ηout, where ηin, ηout denote the inner and the outer viscosities. We found that the equilibrium lateral position of the vesicle exhibits a saddle-node bifurcation as a function of the bifurcation parameter λ, which leads to a surprising acute decrease of the effective viscosity of the suspension at a critical value of viscosity contrast (λc). We found that below a critical viscosity contrast λc, the vesicle is centered, and above λc, the vesicle can be either centered or off-center depending on initial condition. This study can be exploited in the problem of cell sorting out and can help understanding the rheology of confined suspensions.