Laminar Heat Transfer and Fluid Flow in the Entrance Region of a Rotating Duct With Rectangular Cross Section: The Effect of Aspect Ratio

Abstract

A numerical calculation has been performed for the simultaneously developing laminar velocity and temperature fields in the entrance region of an isothermal rectangular duct rotating about an axis perpendicular to the duct axis. The present paper particularly addresses the effect of the aspect ratio of the rectangular duct. The vorticity-velocity method with the power law scheme is employed to solve the governing equations for the flow and heat transfer. It is seen that pairs of counterrotating vortices appear in the cross section of the duct. The number of vortex pairs depends on the aspect ratio of the duct. Under some circumstances, the number of vortex pairs varies with axial position. The numerically calculated stability boundary points for small aspect ratio show excellent agreement with the neutral stability curve, which was obtained by linear stability analysis. Friction factor and Nusselt number are presented as functions of axial position, and it is seen that they are strongly affected by the vortices. Comparisons with existing theoretical and experimental results are also presented.