Basics of lava-lamp convection.
Laboratory experiments are reported in an immiscible two-fluid system, where thermal convection is initiated by heating at the bottom and cooling at the top. The lava-lamp regime is characterized by a robust periodic exchange process where warm blobs rise from the bottom, attach to the top surface for a while, then cold blobs sink down again. Immiscibility allows to reach real steady (dynamical equilibrium) states which can be sustained for several days. Two modes of lava-lamp convection could be identified by recording and evaluating temperature time series at the bottom and at the top of the container: a "slow" mode is determined by an effective heat transport speed at a given temperature gradient, while a second mode of constant periodicity is viscosity limited. Contrasting of laboratory and geophysical observations yields the conclusion that the frequently suggested lava-lamp analogy fails for the accepted models of mantle convection.
Gyüre
Balázs
B
von Kármán Laboratory of Environmental Flows, Loránd Eötvös University, Budapest, Hungary.
Jánosi
Imre M
IM
D003198:Computer Simulation; D008029:Lighting / Q000379:methods*; D008962:Models, Theoretical; D017711:Nonlinear Dynamics