Flow-induced waltzing red blood cells: Microstructural reorganization and the corresponding rheological response

We investigate flow-induced structural organization in a dilute suspension of tumbling red blood cells (RBCs) under confined shear flow. For small Reynolds (Re = 0.1) and capillary numbers (Ca), with fully coupled hydro-dynamic interaction (HI) and without interparticle adhesion, we find that HI between the biconcave discoid particles prompts the formation of layered RBC chains and synchronized rotating RBC pairs, referred here as waltzing doublets. As the volume fraction . increases, more waltzing doublets appear in RBC files. Stronger shear stress disrupts structural arrangements at higher Ca. We find that the flow-induced organization of waltzing doublets changes how the suspension viscosity varies with . qualitatively. The intrinsic viscosity is particularly sensitive to microstructural rearrangement, increasing (decreasing) with . at low (high) Ca that correlates with the change in the fraction of doublets. We verified flow-induced collective motion with comparison to two-cell simulations in which the cell volume fraction is controlled by varying the domain volume.

Automated summary

This study investigates the flow-induced structural organization in dilute suspensions of red blood cells under confined shear flow. The results show that hydrodynamic interaction between the discoid particles leads to the formation of layered RBC chains and synchronized rotating RBC pairs. The presence of more pairs is observed with increasing volume fraction, and stronger shear stress disrupts the structural arrangements.