Maxwell velocity slip and Smoluchowski temperature effects on quadratic radiative water/MoS2−SiO2 Casson hybrid nanofluid flow over an exponentially stretching permeable Riga surface: Dual solutions and entropy generation analysis

A magnetohydrodynamic ( MHD ) water/ MoS 2 – SiO 2 Casson hybrid nanofluid flow over an exponentially stretching permeable Riga surface with the influence of variable thermal conductivity and quadratic thermal radiation is investigated in this study. The Riga plate is an electromagnetic actuator of permanent magnets and alternating electrodes on a flat surface. The impacts of Smoluchowski temperature and the Maxwell velocity slip are also considered. The present numerical simulation also aims to determine the effect of entropy generation and the existence of a dual. A suitable similarity transformation is being used to non-dimensionalize the governing equations and boundary conditions. The transformed nonlinear ordinary differential equations ( ODEs ) were further solved numerically using MATLAB bvp 4 c solver. A tabular and graphical analysis is conducted on the effect of various key parameters on velocity, temperature, skin friction coefficient, Nusselt number, and entropy generation. The acceptable parameter ranges for which the numerical scheme was stable are as follows: 2 ≤ β ≤ 5 , 0.3 ≤ ϖ ≤ 0.7 , 0 ≤ Z ≤ 0.012 , 0.1 ≤ ε 0 ≤ 1.0 , 1.0 ≤ N r ≤ 2.0 , 0.01 ≤ ϕ 1 ≤ 0.06 , 0.01 ≤ ϕ 2 ≤ 0.06 , 1.09 ≤ θ m ≤ 1.11 , 1.0 ≤ R e ≤ 5.0 , 0.2 ≤ ϵ ≤ 0.3 . The Smoluchowski temperature slip parameter ε 0is shown to reduce the thermal boundary layer and heat transfer irreversibility for both the solution branches. The Maxwell slip parameter ϖ in the first solution branch decreases the momentum boundary. The results show that increasing the quadratic radiation and variable thermal conductivity parameter enhanced the heat transfer irreversibility for both solution branches. It has been found that the Nusselt number was reduced by about 66.616 % for the first solution and enhanced by about 63.519 % for the second solution branch, whereas the shear stress coefficient was enhanced by about 8.662 % and 6.369 % by the Smoluchowski temperature slip parameter in the first and second solutions respectively. Also, the Nusselt number is improved by about 4.40 % and 6.57 % by the quadratic thermal radiation parameter for both solution branches. Moreover, an appropriate agreement is obtained by comparing the current and published results. The fluid flow across a Riga plate has several applications in the aerodynamic efficiency of aircraft, automobiles, and heat propagation.