Numerical Study of Natural Convection in an Enclosure with an Internal Heat Source at Higher Rayleigh Numbers

Abstract

Natural convection is extensively used in cooling of large scale electrical and electronic equipments. This work involves study of flow and heat transfer characteristics in enclosures with partial openings having an internal heat source at higher Rayleigh number (Rah > 106). It involves the numerical simulation of 2D steady state natural convection in enclosures of different aspect ratios (H/W = 2 and 3) for five Rayleigh numbers (Rah = 107, 108, 109, 1010, and 1011). Two different configurations have been considered based on the number and position of vents—diagonal side (DS) and two inlets one outlet (2I1O). The time dependent nature of the flow is characterized by performing a Fast Fourier Transform (FFT) analysis of temperature and velocity at a characteristic location in the enclosure. The global parameters considered are the mass flow rate driven through the cavity by the heater and the average Nu defined over the heater surface. It is seen that with increase in Rah, flow becomes more fluctuating and moves towards chaotic regime and this transition is quicker at lower H/W. For the given configuration both the global parameters increases with increase in Rah and decrease in H/W.

Magneto Hydrodynamics Free Convection in a Rectangular Enclosure with Three Square Heated Block

“…Sinusoidal type of variations in heat with Ra=10 5 . Natural convection studies in enclosures with vents and internal heat source at high Rayleigh number (Ra>10 6 ) has been analyzed by Gowrishankar [25]. They observed that with increase in Ra, flow becomes more fluctuating and moves towards chaotic regime.…”