MHD Casson non-Newtonian fluid flow in a channel with expanding/contracting porous walls in the presence of thermal radiation

In this research, we explore the impact of changing viscosity in the context of the asymmetric laminar flow of Casson fluid with thermal radiation. The flow occurs within a channel that can either expand or contract, featuring porous walls. The flow equations are converted into ordinary differential equations (ODEs) through appropriate transformations to simplify the analysis. The velocity field and temperature profile expressions are obtained using Akbari-Ganji's method (AGM) and finite-element method (FEM). The graphs show the impact of different parameters on the flow characteristics, especially the viscosity-dependent parameter, Casson fluid parameter, and expansion ratio. The fluid velocity near the lower wall increases with the Casson fluid parameter but decreases after the mid-point. The fluid velocity is more affected by the temperature-dependent viscosity parameter for Newtonian fluid than non-Newtonian fluid. The results showed that as the Prandtl number increases, the temperature decreases, while the temperature increases with an increase in the Radiation parameter. Also, An increase in the wall expansion ratio leads to higher wall temperatures, whereas a decrease in the power-law index results in reduced temperatures.

The results we've acquired were cross-referenced with prior studies, revealing that the employed methods exhibit high precision. The novelty of the present work is obtaining new results through the use of Akbari-Ganji's semi-analytical method.