Unsteady General Three-Dimensional Stagnation Point Flow of a Maxwell/Buongiorno Non-Newtonian Nanofluid

This paper investigate the unsteady three-dimensional stagnation point flow of a viscoelastic nanofluid past a circular cylinder with sinusoidal radius variation. Buongiorno model is adopted which features the novel aspects of Brownian diffusion and thermophoresis. Similarity transformation is used to reduce the basic equations governing the flow, heat and mass transfer to nonlinear ordinary differential equations (ODE). The resulting nonlinear ODEs are solved analytically by the optimal homotopy analysis method (OHAM) and numerically using the bvp4c function from MATLAB software. Plots have been portrayed in order to explain the role of flow parameters, namely, viscoelasticity, unsteadiness, Brownian motion, thermophoresis, Prandtl number, and Lewis number on velocity, temperature, concentration, skin friction, local Nusselt number and local Sherwood number for both two nodal and saddle points. It is found that heat transfer rate for a maxwellian nanofluid (beta > 0) is more than a Newtonian nanofluid (beta = 0) and the skin friction increases with increasing in viscoelasticity of the flow. Moreover, the higher rate of heat transfer occurs for lower values of the Brownian motion parameter while there is an opposite trend for mass transfer rate.