Effect of High Solid Concentration on Friction in a Transitional and Turbulent Flow of Bioliquid Suspension

Abstract

Some suspensions in nature have a complex structure and demonstrate a yield shear stress and a non-linear relationship between the shear rate and the shear stress. Kaolin clay suspension is such an example in engineering, whereas in nature it is blood. This study represents an innovative approach to simulate bioliquid flow, similar to that of blood when the solid concentration is high. The objective of this study is to examine the influence of high solid concentration of bioliquid, similar to blood, on energy losses and velocity profiles in turbulent and transitional flow in a narrow tube. Using the analogy between the suspension of kaolin clay and blood, the physical model and the mathematical model were formulated. The mathematical model comprises continuity and time-averaged momentum equations, a two-equation turbulence model for low Reynolds numbers, and a specially developed wall damping function, as such suspensions demonstrate the damping of turbulence. Experimental data on blood rheology for solid concentrations equal to 43% and 70% by volume, gathered from the literature, were used to establish a rheological model. The results of the simulations indicated that an increase of solid concentration in bioliquid suspension from 43% to 70% causes an increase in wall shear stress to approximately 10% and 6% for transitional and turbulent flow, respectively, and changes in velocity profiles. Such simulations are important if an inserted stent or a chemical additive to the bioliquid suspension is considered, as they can influence the shear stress. The results of the simulations are presented in graphs, discussed, and conclusions are formulated.