Effect of variable viscosity and wall porosity on the transport of chemically active solute in a three-layered blood flow model

The rheology of blood flow is more complex in microvessels. Because of the accumulation of blood cells (RBCs) at the center of the axis, it behaves as Casson fluid in the core region, while in the absence of blood particles, it behaves as a Newtonian fluid in the outer region. Beyond the clear region, close to the artery, a peripheral region (porous region) is observed. The study plans to understand the effect of variable viscosity, wall porosity, and irreversible absorptive type of reaction (at the tube wall) on solute dispersion through a narrow tube with a three-layered blood flow model. Governing equations are solved analytically, and the dispersion of solute clouds is explained with the help of transport coefficients (exchange coefficient, advection coefficient, and dispersion coefficient), mean concentration, and two-dimensional distribution of solute concentration. The exchange coefficient is solely dependent on the wall absorption rate. The advection coefficient is largely influenced by yield stress, viscosity parameter, viscosity index, viscosity ratio, stress jump factor, permeability parameter, and absorption rate. The axial dispersion coefficient is primarily governed by yield stress, absorption rate, and viscosity parameters, though it is also weakly influenced by the viscosity index, stress jump factor, and permeability parameter.