Oscillatory and relaxation studies in the convection of supercritical He-3

摘要

We analyze the observed temporal profile DeltaT(t) of the temperature difference, measured across a very compressible supercritical He-3 fluid layer in the convective state. The experiments were done along the critical isochore in a Rayleigh-Benard cell after starting the vertical heat flow q. For q > q(ons) ("convection onset"), the transient DeltaT(t) under given conditions of q and e equivalent to (T - T-c)/T-c (T-c = 3.318 K) shows a damped oscillatory profile with period t(osc) modulating a smooth base profile. The latter forms the tail of the transient which relaxes exponentially to the steady-state DeltaT(infinity) with a time constant tau(tail). The scaled times t(osc)/t(D) and T-tail/t(D) from all the data could be collapsed onto two curves as a function of the Rayleigh number over similar to 3.5 decades. Here t(D) is the diffusion time. (C) 2003 Elsevier Science B.V. All rights reserved. [References: 11]