This paper presents a numerical study, supplemented with experiments of flow visualization and holographic interferometric measurement, concerning the buoyancy-induced fluid flow and heat transfer between two horizontal, differentially heated cylinders inside a circular, air-filled enclosure subjected to external convection. Numerical simulations via a finite-difference method have been conducted mainly to investigate the effect of insulation (namely, the external convection boundary condition) at the circular enclosure wall on the buoyant air flow structure and heat transfer characteristics among the horizontal cylinders and the circular enclosure wall. The results are displayed graphically to emphasize the effects of the Rayleigh number (Ra = 104∼107), the inclination angle of the enclosure with respect to gravity (φg = 30, 60, 90°) and the gap width between the horizontal cylinders (s/d = 0.7, 0.8333, 1.0) in the presence of external convection. The external convection at the circular enclosure wall was found to further promote buoyant convection flow and a markedly enhanced heat transfer between the cylinders accordingly results. In addition, the simulation taking account for the external convection at the enclosure wall was found to compare favorably with the experimental results of flow visualization and temperature distribution in a test cell with imperfect thermal insulation.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Mechanical Engineering
- Fluid Flow and Transfer Processes