ISSN Online: 2377-424X
ISBN Print: 0-89116-299-2
International Heat Transfer Conference 7
OVERSHOOTING AND DAMPED OSCILLATIONS OP TRANSIENT NATURAL CONVECTION FLOWS IN CAVITIES
Abstract
Transient calculations for a two-dimensional cavity with two isothermal and two adiabatic walls were performed. Imposing a step change on the wall temperatures, the calculated transient response shows an overshooting of the maximum value of the stream function, followed by damped oscillations around its steady state value. The mean Nusselt number shows similar oscillations. The frequency of the oscillations was determined to depend on Ra0.5 which is in agreement with theoretical and experimental observations of other authors. The influence of the Prandtl number depends on the geometric configuration. The damping of the oscillations decreased with increasing Rayleigh number. This is believed to be the reason for the transition to time-dependent convection and to turbulence at higher Rayleigh numbers.