Simulation of Natural Convection from an Eccentric Horizontal Circular Cylinder in an Enclosure
Tarak Shaw1,a, Subhashis Ray2 and Prabir Kumar De1,b
1Department of Mechanical Engineering, Jadavpur University, Kolkata 700 032, India.
atarak_shaw_ju@yahoo.co.in
bfm_prabir_de@yahoo.co.in
2Institute of Thermal Engineering, Technische Universität, Bergakademie, Freiberg Gustav-Zeuner Straße 7, D-09596 Freiberg, Germany.
ray@iwtt.tu-freiberg.de
ABSTRACT
Natural convection heat transfer from a heated horizontal cylinder, placed within a cold square enclosure has been numerically studied using curvilinear coordinates on non-staggered grid. The density variation has been incorporated by employing the Boussinesq approximation. The results have been obtained for a wide range of Rayleigh number, 103≤ Ra ≤106 and for different vertical eccentricities, varying between −0.3 and +0.3. The results show the existence of two distinct regimes: the conduction dominated regime at low Rayleigh number, where the Nusselt number remains almost constant, and the convection assisted regime, where the Nusselt number significantly increases with the increase in Rayleigh number. The threshold value of Rayleigh number, upto which the conduction dominated regime prevails, has been found to be a weak function of fluid although it increases with the increase in vertical eccentricity. It has been further observed that in the low Rayleigh number regime, the average Nusselt number first decreases with the increase in vertical eccentricity and reaches a minimum value, beyond which it again increases with the vertical eccentricity. With the increase in Rayleigh number, particularly in the intermediate Rayleigh number regime, the vertical eccentricity, where the minimum Nusselt number is observed, has been found to move upwards. Finally, for very high Rayleigh numbers, the average Nusselt number has been observed to decrease continuously with the increase in vertical eccentricity.
Full Text (PDF)
|
