Abstract
The motion of red blood cells (RBCs) in microcirculation plays an important role in blood flow resistance and in the cell partitioning within a microvascular network. Different shapes and dynamics of RBCs in microvessels have been previously observed experimentally including the parachute and slipper shapes. We employ mesoscale hydrodynamic simulations to predict the phase diagram of shapes and dynamics of RBCs in cylindrical microchannels, which serve as idealized microvessels, for a wide range of channel confinements and flow rates. A rich dynamical behavior is found, with snaking and tumbling discocytes, slippers performing a swinging motion, and stationary parachutes. We discuss the effects of different RBC states on the flow resistance, and the influence of RBC properties, characterized by the Föppl-von Kármán number, on the shape diagram. The simulations are performed using the same viscosity for both external and internal fluids surrounding a RBC; however, we discuss how the viscosity contrast would affect the shape diagram.
Highlights
The behavior of so mesoscopic particles in ow has recently received enormous attention due to the wide range of applications of such suspensions and their rich physical properties.[1]
Coupling between the uid ow and red blood cells (RBCs) deformation is achieved through viscous friction between RBC nodes and surrounding uid particles, which is implemented via dissipative particle dynamics interactions.[8]
Orbital oscillations of a tumbling RBC are attributed to local membrane stretching deformation due to small membrane displacements whose effect becomes reduced if a RBC transits to a rolling motion.[39]
Summary
The behavior of so mesoscopic particles (e.g., polymers, vesicles, capsules, and cells) in ow has recently received enormous attention due to the wide range of applications of such suspensions and their rich physical properties.[1]. It is important to note that these shapes (averaged over thermal uctuations) are characterized by different symmetry classes, ranging from cylindrical symmetry (parachutes) to a single mirror plane containing the capillary axis and the RBC center (slippers). This raises several important questions: are slipper shapes stable in 3D capillary ow? Importance in various blood diseases and disorders.[22] The presented 3D shape diagrams describe RBC deformation in microchannels, which mimic small vessels in microcirculation, and show that the parachute shape occurs mainly in small channels, while in large channels the slipper shape may occur. The RBC membrane is represented by a triangulated network model[7,8,25,26] and coupled to a uid through friction forces
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