Gas spreading on a heated wall wetted by liquid - art. no. 051602

This study deals with a simple pure fluid whose temperature is slightly bel ow its critical temperature and whose density is neatly critical, so that t he gas and liquid phases coexist. Under equilibrium conditions, such a liqu id completely wets the container wall and the gas phase is always separated from the solid by a wetting film. We report a striking change in the shape of the gas-liquid interface influenced by heating under weightlessness whe re the gas phase spreads over a hot solid surface showing an apparent conta ct angle larger than 90 degrees. We show that the two-phase fluid is very s ensitive to the differential vapor recoil force and give an explanation tha t uses this nonequilibrium effect. We also show how these experiments help to understand the boiling crisis, an important technological problem in hig h-power boiling heat exchange.