Numerical Study of Natural Convection from a Horizontal Cylinder with Different Cross Sections

Laminar free convection heat transfer from an isothermal horizontal unbounded cylinder of four circular, equilateral triangular, slender and blunt elliptical cross-sections is numerically investigated. The fully developed momentum and the standard energy governing equations are transformed into a non-dimensional form and the resulting nonlinear systems of partial differential equations are then solved numerically applying the finite volume technique. This paper focuses on the effect of using different cross-sections of the cylinder and Rayleigh number variation on the local and average free convection heat transfer from the cylinder surface. The results show that the heat transfer rate by free convection increases significantly with an increase in Rayleigh number for all cylinders. Moreover, the local and average heat transfer from the elliptical cylinder with slender orientation is found to be much higher than other cylinders.