Two-phase convection

Shadowgraph movies corresponding to Figs. (5a), (5b), (5e), and (5f) of "Enhanced heat transport by turbulent two-phase Rayleigh-B\'enard convection" by J.-Q. Zhong, D. Funfschilling, and G. Ahlers. When played at 30 frames per second, (5a) and (5b) they run at 11 times real speed and (5e) and (5f) run at 2.3 times real speed. For (5a) the entire sample is in the gas phase just above the phase-separation temperature $T_\phi$. For (5b), (5e), and (5f) 8\%, 68\%, and 42\% respectively of the applied temperature difference is below $T_\phi$. The movies show the vertically integrated lateral refractive-index variation. For (5a) the the entire sample is just above the phase-separation temperature $T_\phi$; the shadowgraph signal is due to plume and thermal-fluctuation activities. For (5b), (5e), and (5f) 8\%, 68\%, and 42\% respectively of the applied temperature difference is below $T_\phi$. For (5b) a thin layer just under the top plate is meta-stable and the black circles are liquid droplets that condense under the top plate and are swept laterally by the large-scale circulation. In (5e) the entire sample is filled with liquid, and a thin layer just above the bottom plate is meta-stable. The black circles are vapor bubbles forming at the bottom, rising due to buoyancy and moving laterally with the large-scale circulation, and dissolving in the warmer sample interior. In (5f) the vapor bubbles are able to reach the sample top where they form a large bubble. Liquid droplet condensation takes place inside this large bubble.

From "Enhanced heat transport by turbulent two-phase Rayleigh-B\'enard convection", J.-Q. Zhong, D. Funfschilling, and G. Ahlers, Phys. Rev. Lett., in print.

Two-phase convection: An mpg movie (5 MB) corresponding to Fig. 5a showing its dynamics can be found here.

Two-phase convection: An mpg movie (5 MB) corresponding to Fig. 5b showing its dynamics can be found here.

Two-phase convection: An mpg movie (5 MB) corresponding to Fig. 5e showing its dynamics can be found here.

Two-phase convection: An mpg movie (5 MB) corresponding to Fig. 5f showing its dynamics can be found here.