Thermofluidic analysis around a heated hollow spherical ring immersed in air

Abstract

Efforts are made to report a numerical investigation on natural convection flow around a heated vertical hollow spherical ring with negligible wall thickness exposed in quiescent air within laminar regime. Both inner and outer walls are maintained at a constant temperature throughout the study. Thermal and flow fields are predicted thoroughly over the wide range of following governing pertinent parameters: height-to-diameter ratio and Rayleigh number ( First, thermal plumes are employed to understand the thermofluidic behavior around the spherical ring qualitatively. A high-temperature zone inside the spherical ring is identified at higher value aspect ratio almost for all values of due to the entrapment of the heated plume. It is also noticed that the cooling rate from inner wall first increases with and finds a maximum value then starts to drop with a further rise of for a constant value of This maximum value is almost 7.1 times higher at 107 compared to 103, whereas it is approximately 3.75 times higher at 106 compared to 103. However, the heat loss rate from outer wall increases continually with the progressive rise of for a fixed value of However, the mean Nusselt number on both inner and outer walls reduces with the increase of for all cases of Again, the pattern of mass flow rate through the ring is also predicted for various values of and The mass flow rate reduces progressively with the continual rise of for a fixed value of Lastly, the study is concluded by developing a suitable correlation for net Nusselt number based on the computed data points which shows a satisfactory agreement within ±6% of the computational data.