Laminar Natural Convection From Isothermal Vertical Cylinders: A Revisit to a Classical Subject

Laminar natural convection heat transfer from the vertical surface of a cylinder is a classical subject, which has been studied extensively. Furthermore, this subject has generated some recent interest in the literature. In the present investigation, numerical experiments were performed to determine average Nusselt numbers for isothermal vertical cylinders (10³ < Ra_L < 10⁹, 0.5 < L/D <10, and Pr = 0.7) situated on an adiabatic surface in a quiescent ambient environment which will allow for plume growth. Results will be compared with commonly used correlations and a new average Nusselt number correlation will be presented. Furthermore, the limit for which the heat transfer results for a vertical flat plate may be used as an approximation for the heat transfer from a vertical cylinder will be investigated.