Laminar convection in rectangular ducts of fully developed flow

Abstract

Benchmark calculations for the Graetz problem in rectangular ducts are performed for three wall conditions (T – constant temperature, H2 – constant heat flux, and H1 – constant axial heat input with constant peripheral temperature). Results are reported for a wide range of duct aspect ratio (1/1 through 1/10) and over a wide span of inverse Graetz number (Z>10−6). This builds on earlier works that neglect the initial ~20% of thermal boundary layer growth in reporting heat transfer results and that omit the H2 wall condition. Using a new generalized approach, Nusselt number results for the T and H1 wall condition are correlated to better than ±2.5% for the entire range of inverse Graetz number and duct aspect ratios. Limitations on correlating the H2 wall condition by the same method are discussed.