Numerical analysis of red blood cells suspension and platelets margination in curved microvessels

Our body contains about 60'000 miles of blood vessels, many of which are tortuous vessels twisting into each other. To understand the origin of the complex phenomena appearing in microvessel, it is vital to examine how blood cells move inside these vessels. Although there have been many studies in cellular flow simulations in straight vessels, there have been few studies on understanding the probable phenomena happening inside the curved ones. The current study aims to fill this gap. We used an open-source code HemoCell, which is based on the combined immersed boundary and lattice Boltzmann methods, to simulate dense suspensions of deformable red blood cells (RBC) and platelets. Various validation cases have been tested including single RBC stretching, RBC deformation in shear flow, and RBC suspension in straight microvessels. Fåhræus and Fåhræus–Lindqvist effects were investigated. Next, we discuss the simulation of cellular flow in curved microvessels with various diameters (from 20 to 64 μm), capillary numbers, and hematocrits. Comparisons have been made to understand the difference between RBC suspensions within straight and curved microvessels. We have investigated how the bending of the vessels affects relative apparent viscosity and platelet margination in detail.