Effect of adiabatic ground on thermofluidic behavior and cooling time analysis from a hollow tube

Abstract

Efforts are made to elucidate natural convection around a tube placed on/close to the adiabatic ground in a stagnant ambient air within laminar regime. Thermofluidic characterization is carried out by employing important governing input quantities, such as Rayleigh number gap and aspect ratio The heat loss rate from the inner surface drops abruptly when the tube is placed on the ground. The growth rate of heat loss rate with is relatively more abrupt at higher value of for a constant Nusselt number on outer wall is found to increase monotonically as grows continually for a constant and whereas an opposite trend is anticipated for Nusselt number on inner wall The reduction gradient of with is considerably lower at lower value of in comparison to higher Again, two distinguished zones are identified (Zone A and B), namely, (i) zone A, where the effect of ground on the thermofluidic behvaiour around the tube is observed, and (ii) zone B suggests no effect of ground. Furthermore, cooling time estimation is performed by considering the initial temperature of the cylinder as the wall temperature at time 0 s. The required cooling time reduces considerably with the rise of for a particular and Lastly, a new correlation for Nusselt number has been anticipated. It shows quite satisfactory agreement within ±6% of the computational data.