PERTURBATION SOLUTION OF COUETTE FLOW OF CASSON NANOFLUID WITH COMPOSITE POROUS MEDIUM INSIDE A VERTICAL CHANNEL

Background-Immiscible flows are significant to predict the liquid-liquid and liquid-particles in-teraction, especially, transporting in the same geometry. One good reason for the application of such multilayer flows is the idea of dragging one kind of fluid by viscous shear stress of another type of fluid. In this context, a three-layer fluid flow model with nanofluid is formulated in this paper, for either no or little attention has been paid to such technological flow problems in a vertical channel with heat transfer characteristics. Double layers of immiscible flow have been commonly applied in industrial equipment, such as cooling equipment, heat exchangers, nuclear reactors, etc. Method-Couette flow of Casson nanofluid with variable viscosity and porous medium inside a ver-tical channel is examined in this work. We have assumed three different regions in which Regions I and III are clear viscous regions while Region II is the porous medium saturated region. The Tiwari and Das model was used to obtain governing equations of the existing problem, and Darcy's law was considered for porous medium. The energy equation also included viscous and Darcy dissipation terms. By using the regular perturbation technique, the results of developed dimensionless governing equations are calculated. Results-On the flow characterization of the Casson nanofluid, the inspections are executed with the help of graphs for altering values of the porous parameter, Grashof number, Brinkman number, and solid volume fraction. It is assessed that the Brinkman number and Grashof number accelerated the velocity and temperature of the fluid in all three regions. It is also observed that the porous parameter and solid volume fraction parameter decline both the flow and the temperature of the fluid.