Blood rheology using a Brownian dynamics simulation of bead spring ring with a constant area

Coronary artery disease is epidemic in the western world. Occlusive vascular disease, when considered in terms of total incidence rather than separated to organ involvement, is the leading human's health hazard. A better understanding of occlusive vascular disease is so important that does not need to be justified. Blood theological properties are important factors in the occurrence and onset development of these diseases and may help in a rational approach to predictive and anticipatory therapies. Blood is a suspension of red blood cells (RBC) and therefore has a complex flow behavior. This research presents a Brownian dynamics (BD) model that captures the complex rheological behavior of blood; a three-bead-spring ring with a holonomic constant area constraint is being used to model the RBC in a dilute Newtonian solvent. The BD model has been used in simulations of RBCs to generate the RBC configuration. The stress tensor or momentum flux tensor is obtained as an ensemble average over molecular configurations by Giesekus expression of the stress calculator. This stress calculator makes it possible to obtain the RBC rheological properties of the model blood suspension under different flow conditions: homogeneous simple shear flow, elongational flow, inception of a steady shear flow, stress relaxation after cessation of steady shear flow and flow within narrow vessels by considering the blood microstructure scale process. The model's main results obtained for the specified flows are as follows: (a) Simulations in steady shear flow in an unbounded space the dilute blood suspension model expresses both shear thinning behavior for the viscosity and first normal stress coefficient. (b) In steady elongational flow, the elongational viscosity of the dilute blood suspension increases when the elongational rate increases. (c) Stress growth upon inception of steady shear flow; increasing shear rates does the shear stress approach its steady state monotonically. (d) Stress relaxation after cessation of steady shear flow; the response is that the ring reaches equilibrium in a very short, but finite time. (e) The non-Newtonian behavior of the blood is evident in small branches and capillaries where the cells squeeze toward the vessel axis, and the model clearly expresses the Fahraeus effect and the Fahraeus-Lindqvist effect.