Einfluß der Wandwärmeleitung auf die laminare Mischkonvektion in der thermischen Eintrittszone von horizontalen, rechteckigen Kanälen

Abstract

This paper presents a numerical study of the effect of peripheral wall heat conduction on laminar mixed convection in the thermal entrance region of horizontal rectangular channels. In addition to the Rayleigh numberRa and the channel aspect ratio (width-to-height) γ, the wall heat conduction parameterK=kwt/(kfDe) plays an important role in heat transfer. A numerical method of solution utilizing the vorticity-velocity formulation is developed to solve the system of governing partial differential equations coupled with the boundary condition equation considering peripheral wall heat conduction. Local friction factor ratio and Nusselt number variations are shown forPr=0.7,Ra=104, 3×104, and 105, γ=0.2, 0.5, 1, 2 and 5,K=0.01, 0.1 and 1. The effect of peripheral wall heat conduction on Nusselt number is found to be significant when the value of γ is less than 1. The asymptotic solutions forz→∞ are compared with the existing numerical results and good agreement is indicated.