A comparative analysis of CFD and LBM for investigating the effects of endothelial glycocalyx on the bifurcating blood flow.

The surface of vascular endothelial cells is covered by endothelial glycocalyx. The fragile, hair-like structure of endothelial glycocalyx makes difficult to gauge its interactions with circulating blood flow and cells in experimental settings. Numerical simulations, capable of mimicking intact or damaged glycocalyx conditions, have emerged as an effective tool to understand the interplay between the endothelial glycocalyx and blood flow, although results may vary due to algorithmic differences. In the present study, classical CFD (computational fluid dynamics) and LBM (lattice Boltzmann method) were used to mimic the interactions between the endothelial glycocalyx and blood flow. The effects of endothelial glycocalyx intactness on blood flow velocity and shear stress were investigated under physiologically relevant conditions. The effects of vessel geometry on red blood cell movement and the effects of glycocalyx intactness were further studied in the CFD simulations. The results suggested that the flow velocities in the downstream branches, which are determined by the blood vessel diameters, affected the movement of red blood cells in the upstream feeding-channel significantly. The findings agree with the Zweifach-Fung effect reported previously. Additionally, the flow profiles and computational execution details of the CFD and LBM were compared. Notably, LBM can capture fine details of the flow and exhibits higher computational efficiency, approximately 15 times that of the CFD method. The findings will clarify the behavior of the blood flow over the complicated vessel surface and provide insights for the selection of optimal numerical methods in solving blood flow problems on topographically complex surfaces.