Paper 4: Terminal Laminar Convection in a Uniformly Heated Rectangular Duct

Abstract

For the laminar flow of a fluid with constant properties in a uniformly heated rectangular duct with no viscous dissipation and internal heat release, an exact solution for the fluid temperature field is presented in the form of rapidly convergent infinite series. Expressions are subsequently derived for the variation of limiting Nusselt number, based on unweighted and weighted mean temperature differences, with duct aspect ratio.

It is shown that previously published approximate solutions for the weighted Nusselt number—determined using numerical techniques—are in agreement with the more versatile exact solution to better than 1 per cent.