On the natural convective heat transfer from a cold horizontal cylinder over anadiabatic surface

A steady two-dimensional laminar free convection heat transfer from a cold horizontal isothermal cylinderlocated above an adiabatic floor is studied both experimentally and numerically. In the experimentalmeasurements the effects of cylinder distance from horizontal floor to its diameter (L/D) on heat transfercoefficient is studied for Rayleigh numbers of 3×105 and 6×105. Computations are made using OpenFOAM (anopen source) code for wide range of Rayleigh numbers from 104 to 106 and comparisons are made with thecorresponding experimental measurements. Flow stream lines and isothermal lines are plotted for differentcylinder relative positions. Results indicate that cold plume flows downstream and strikes to the horizontal floorand moves horizontally away from cylinder over the horizontal floor. The finite space between cylinder and floormakes the flow different from those cylinders surrounded by an infinite medium. Results also indicate thatvariation of average heat transfer coefficient of the cold cylinder is highly affected by L/D. A new correlation forestimation of convection heat transfer for a single horizontal cylinder placed over an adiabatic floor is alsodeveloped.

Keywords:

Free convection , Laminar flow , Cold horizontal cylinder , Adiabatic floor , OpenFOAM