This talk starts with a tutorial on supercritical fluids and on
convection in a Rayleigh-Benard cell. The fluid is 3He, which near
the liquid-vapor critical point at behaves like other
pure fluids. The combination of Rayleigh - and Schwarzschild criteria
to determine the stability limit near is described, and the
predictions are compared with experiments. After a heat flow has been
started across the fluid layer, an oscillatory behavior of the
temperature difference across the layer is observed versus time in
the convective regime. This phenomenon is the signature of the
"piston effect", which will be described. Scaled plots of both
steady state - and transient characteristic times as a function of
the Rayleigh number at various compressibilities and heat currents
are presented. Simulations and calculations by groups in Japan and
France are compared with the experimental data.
References: A. Furukawa, H. Meyer et al: Phys. Rev. E 68, 056309 (2003), H. Meyer and A.B. Kogan : Physical Review E 66, 056310 (2002), A. B. Kogan and H. Meyer: Phys. Rev. E 63, 056310 (2001)
Seminarsko predavanje bo v cetrtek 9. septembra 2004 ob 15:15 uri v seminarski sobi CAMTP, Krekova 2, pritlicje desno. Vljudno vabljeni vsi zainteresirani, tudi študentje.