Impacts of Nonlinear Buoyancy and Variable Viscosity on Steady Mixed Convection Couette Flow With Heat Generation/Absorption

ABSTRACT The purpose of this study is to investigate the effects of nonlinear buoyancy and temperature‐dependent viscosity on mixed convection Couette flow in the presence of heat generation/absorption. A mathematical formulation based on the governing momentum and energy equations is developed, and the resulting nonlinear equations are solved using the homotopy perturbation method. The parametric analysis shows that both viscosity variation and nonlinear buoyancy significantly influence the velocity and temperature fields, particularly near the channel walls. An increase in viscous dissipation enhances the velocity near the heated wall, while an opposite behavior is observed near the cooled wall, and it also raises the temperature throughout the channel. Higher viscosity leads to increased velocity and temperature close to the heated wall but produces reverse trends near the cooled wall. Similarly, increasing the nonlinear buoyancy parameter accelerates the flow near the heated wall while inducing a reverse effect near the cooled wall, and it elevates the temperature across the channel. Moreover, increased viscous dissipation intensifies the shear stress at the heated wall while reducing it at the cooled wall. Both the mean temperature and the rate of heat transfer at the walls increase as the Prandtl number rises from that of mercury to air . The onset of reverse flow occurs when and noticed that, the increase in increases the reversal flow on the cooled wall.