Shear stress variation induced by red blood cell motion in microvessel.

We simulated red blood cells flowing in microvessel to examine the induced wall shear stress variation. A typical peak-valley-peak structure is observed, and it is analyzed in terms of its magnitude, spatial influencing range, and temporal elapsed duration. Effects of red cell deformability, microvessel size, and flow velocity have been investigated. The corresponding variation characters have also been related to cell deformation and flow field. Simulation results show that the variation magnitude is mainly determined by the gap size between cell and vessel wall, while the spatial range of the shear stress variation depends on the cell length as well as the microvessel size. For a certain point on the vessel wall, the shear stress variation lasts a short time at a higher flow velocity, and vice versa. As the cell concentration in the microvessel increases, the shear stress variation structure changes accordingly with the two peaks from two close cells merging together, and eventually only one peak is observed at a hematocrit of 30.72%. However, the effect of hematocrit on the variation magnitude of shear stress is less obvious, and the dynamic nature of shear stress is still significant. This represents the first attempt to study the dynamic shear stress variation on microvessel as red blood cells flow by, and the information obtained in this study could be valuable to relevant research, for example, the mechanotransduction in the endothelia glycocalyx layer.