Mixed convection heat transfer in horizontal rectangular ducts with wall transpiration effects

A detailed numerical study was carried out to examine the effects of wall transpiration on laminar mixed convection flow and heat transfer in the entrance region of horizontal rectangular ducts. The vorticity-velocity method was employed in the formulation. Both thermal boundary conditions of uniform heat flux (UHF) and uniform wall temperature (UWT) were considered. Predicted results are presented for air flow over a wide range of governing parameters. In this work, the wall Reynolds number Re_w are varied from - 2 (suction) to 4 (injection) with Rayleigh numbers Ra ranging from 0 to 2 × 10⁵ for aspect ratios γ = 0.2, 0.5, 1, 2 and 5. The predicted results show that either wall injection or wall suction has a considerable impact on the flow structure and heat transfer performance. In addition, the correlating equations for the average fRe and Nu are presented.