| Popis: |
Numerical investigation of mixed convection heat transfer in a three-dimensional, horizontal, rectangular duct has been carried out using COMSOL Multiphysics® simulation software. The bottom wall of the duct is subjected to a uniform heat flux condition, while the top and sidewalls are adiabatic. Uniform flow of water at 23°C (Pr = 6.5) is assumed to enter the duct of aspect ratio in the range of 1 ≤ A ≤ 10. Numerical computations are carried out for Re = 500 and modified Grashof number (Gr*) in the range of 2.5 × 105 ≤ Gr* ≤ 6.5 × 106. Results of the flow structure, local averaged friction factor (f), and local averaged Nusselt number (Nu) at the bottom of the duct for Re = 500, A = 2, and Gr* = 2.5 × 106 are compared with those from Incropera et al. [11]. Additionally, Nu values are also obtained for increased values of A and Gr* and compared with results from Incropera et al. [11]. Alongside incompressible flow with Boussinesq approximation, results are obtained for the weakly compressible form of the body force terms available in COMSOL Multiphysics®. Results show good agreement with published results in the literature, and the two results from the two approaches to approximating the body force terms are largely similar except at high Gr*. Additionally, a maximum heat transfer enhancement by buoyancy of ≈ 310% was found. |
