Heat and mass transfer characteristics in flow of bi-viscosity fluid through a curved channel with contracting and expanding walls: A finite difference approach

This article investigates the heat and mass transfer in flow of bi-viscosity fluid through a porous saturated curved channel with sinusoidally deformed walls. The magnetic field and Joule heating effects are also taken into account. The equations describing the flow and heat/mass transfer are developed using curvilinear coordinates. A reduction of these equations is made based on lubrication approximation. The reduced linear ordinary differential equations are integrated numerically using an implicit finite difference scheme. It is observed that, the bi-viscosity fluid parameter, permeability parameter, and Hartmann number have analogous effects on the longitudinal velocity. Moreover, temperature of the fluid, heat coefficient, and mass concentration increase by increasing bi-viscosity fluid parameter, Brinkmann number, and Hartmann number. Further, mass concentration increases by increasing the rate of chemical reaction and bi-viscosity parameter. The size of circulating roll in lower half of the channel boosts up with larger variation of bi-viscosity parameter and permeability parameter. The flow patterns in the channel illustrating the effects of bi-viscosity parameter, permeability parameter, and Hartmann number are also displayed.