ANALYTICAL AND NUMERICAL STUDY OF HEAT TRANSFER IN LAMINAR PULSATILE FLOW AROUND A HEATED CYLINDER

摘要

The aim of the present paper is to study analytically and numerically the heat transfer mechanism between a laminar pulsatile flow in annular space and a heated cylinder. Numerical results obtained by a finite difference method indicate clearly how pulsation affects the rate of heat transfer and how the phenomenon depends on the kinetic Reynolds number Re_ω. Computations are carried out for a kinetic Reynolds number range of 0≤Re_ω≤1000, while the pulsation amplitude is fixed at a value A_w = 0.75 and the Prandtl number (Pr=0.7). The temporal variation of temperature shows the progressive disappearance of the oscillatory aspect at the outlet of conduct where the heat transfer is caused principally by conduction. The oscillatory aspect is more present as the frequency Reω is low. This aspect disappears gradually for the high frequencies Re_ω=1000. The results also showed that the temperature gradient is significant at the inlet of annular space. It decreases with z coordinate. The relative mean Nusselt Number (Nu_(ps))_m is varied with frequency about two modes. For the low frequencies the heat transfer is significant along the cylindrical wall, but for the high frequencies the heat transfer does not change practically with the pulsations at the outlet of the annular space. On notes a good agreement between the analytical and the numerical methods.