Mixed Convection Heat Transfer From Swirling Open Spherical Cavity

This work reports a numerical study on mixed convection flows around a swirling spherical shaped open vessel in air within the laminar regime. This investigation is quite important and relevant in various industrial operations like centrifugal casting, formation of shield surfaces, thermal processing of different food stuffs, etc. This study aims to characterize the fluid flow and heat transfer behavior from both inner and outer surfaces of the open cavity. Governing differential equations, such as continuity, momentum, and energy are solved by using finite volume technique to describe the effect of relevant pertinent parameters over wide range: Rayleigh number $(103≤Ra≤107)$⁠, height to diameter ratio $(0.15≤h/D≤0.95)$⁠, and Reynolds number $(0≤ReD≤300)$⁠. It is observed that the plume is deformed greatly by swirling effect at higher $ReD$ and lower $Ra$ for a fixed $h/D$⁠. The percentage of increase of heat transfer rate from $ReD=0$ to $ReD≠$ 0 is significantly higher at lower $Ra$ for all cases of $h/D$⁠. Lastly, a suitable correlation for average Nusselt number is proposed as a function of $Ra$⁠, $h/D$⁠, and $ReD$⁠, which shows a satisfactory agreement with numerical data. This correlation is expected to be helpful for academic and industrial purposes.