Numerical simulation of red blood cell aggregation under pulsatile flow with depletion model

Shear rate is known to be a determining factor for red blood cell (RBC) aggregation and thus has significant effects on ultrasound backscattered power from blood. But shear rate could not fully explain the cyclic variation of backscattered power from blood under pulsatile flow. The flow acceleration was suggested as another hemodynamic factor to enhance the RBC aggregation and thus backscattered power from blood. In this study, two RBCs were placed along a streamline during the deceleration phase of the pulsatile flow, and the time for two RBCs to form a rouleau was numerically simulated with depletion model. Furthermore, 393 RBCs were randomly placed under pulsatile flow and laminar flow, and the results were compared. Results reveal that flow acceleration would increase the RBC aggregation speed and mean aggregate size (MAS).