Combined Forced and Free Convection in the Entrance Region of an Isothermally Heated Horizontal Pipe

Abstract

Numerical solutions are given without the aid of a large Prandtl number assumption for combined forced and free laminar convection in the entrance region of a horizontal pipe with uniform wall temperature. The steady-state solutions have been obtained from the asymptotic time solutions of the time-dependent equations of momentum and energy with the Poisson equation for pressure. Results are presented for the developing primary and secondary velocity profiles, developing temperature fields, local wall shear stress, and local and average Nusselt numbers, which reveal how the developing flow and heat transfer in the entrance region are affected by the secondary flow due to buoyancy forces.

Mixed convection heat transfer in horizontal rectangular ducts with radiation effects

“…Cheng et al [9], Ou et al [10] and Cheng and Ou [11] employed the assumption of large Prandtl number to study the mixed convection heat transfer in the thermal entrance region of horizontal rectangular channels. The same problems were also examined for a horizontal tube by Hieber and Sreenivasan [12], Hong et al [13], Ou and Cheng [14] and Hishida et al [15]. Their results showed that the secondary flow induced by the thermal buoyancy force can enhance significantly the heat transfer.…”

Heat Transfer and Pressure Drop Characteristics of Smooth Horizontal Tubes in the Transitional Flow Regime

“…This would then give rise to the higher friction factors. Many numerical and experimental studies that have been performed show this distortion [33][34][35].…”

Combined heat and mass transfer for laminar flow of moist air in a 3D rectangular duct: CFD simulation and validation with experimental data

“…There are a lot of research works on the determination of heat and mass transfer coefficients considering the effect of buoyancy forces and a large share of it belongs to the internal flows . Whereas some of the works consider only heat transfer [9][10][11][12][13][14][15][24][25][26][27][28] to quantify Nusselt number, many of them treat simultaneous heat and mass transfer [16][17][18][19][20][21][22][23]29,30] to determine Nusselt and Sherwood numbers together. Most of the works in the literature present numerical data and correlations [9][10][11][12][13][16][17][18][19][20][21][22][24][25][26][27][28]30] with only a few presenting experimental data and correlations [14,15,23,29].…”