Stefan blowing and activation energy impacts on stagnation-point flow of variable viscosity nanofluids over a solid sphere embedded in exponentially heat-generating porous media

Abstract

Flow along a solid sphere is used in many single-and two-phase engineering applications, including towing sonar, food and chemical manufacturing, moving bodies in water-based, pneumatic equipment and hydraulic conveying, raindrops, silt conveyance in waterways, combustion systems, and sport balls. Due to this importance, this paper aims to examine Stefan blowing and thermal slip impacts on the mixed convection over a solid sphere using an efficient finite difference method with the Blottner algorithm. The forced situation is due to the presence of a stagnation-point in the flow area, and the considered layer is filled by isotropic porous elements. The worked suspension is a type of nanofluid where the dynamic viscosity is variable as a function of temperature. Beside, significant impacts are examined, such as non-linear thermal radiation, exponential heat generation, and exponential chemical reaction. The solution methodology is depending on transforming the governing system into non-similar formulations and evaluating pressure gradients using free-stream velocity. The major observations here are that when θ r > 0 (positive values of the fluid viscosity parameter), the growing in θ r causes a decrease in skin-friction while the heat transfer rate is enhanced. Also, the temperature is improved as either the Stefan parameter or the thermal slip parameter is increased.