Abstract
The time profile of the temperature difference, measured across a very compressible fluid layer of supercritical after the start of a heat flow, shows a damped oscillatory behavior before steady-state convection is reached. The results for obtained from numerical simulations and from laboratory experiments are compared over a temperature range where the compressibility varies by a factor of ≈40. First the steady-state convective heat current as a function of the Rayleigh number is presented, and the agreement is found to be good. Second, the shape of the time profile and two characteristic times in the transient part of from simulations and experiments are compared, namely (1) the oscillatory period, and (2) the time of the first peak after starting the heat flow. These times, scaled by the diffusive time versus Ra, are presented. The agreement is good for where the results collapse on a single curve showing a power-law behavior. The simulation hence confirms the universal scaling behavior found experimentally. However for where the experimental data also collapse on a single curve, the simulation results show systematic departures from such a behavior. A possible reason for some of the disagreements, both in the time profile and in is discussed.
- Received 21 May 2003
DOI:https://doi.org/10.1103/PhysRevE.68.056309
©2003 American Physical Society