Effects of a finite section with linearly varying wall temperature on mixed convection in a vertical channel

Laminar mixed convection in a vertical channel with a finite section of a linearly varying wall temperature is numerically investigated. Dramatic variations of local velocity, temperature, local and average Nusselt numbers are plotted to demonstrate the influences of investigated parameters including Reynolds number, Grashof number and the degree of wall temperature variation. Particular attention is paid to reveal the effects of linearly varying temperature. The results suggest that the average Nusselt number Nu¯ increases with Re and Gr. Moreover, Nu¯ is higher with a linearly increasing wall temperature than that with a linearly decreasing wall temperature. Finally, an excellent correlation is proposed to predict Nu¯ over the wide ranges of investigated parameters.