Dynamics of a condensing liquid film under conjoining/disjoining pressures

The dynamics of a condensing apolar ultrathin liquid film is studied in the framework of long-wave theory in the cases of both horizontal and slightly tilted solid coated surfaces. When condensation is slow, the film on a hor izontal substrate passes through the stages of hole opening driven by the " reverse reservoir effect," hole closing, eventual thickness equilibration a nd further spatially uniform growth of the condensate. When condensation is faster and the resistance to phase change is lower, secondary droplet(s) m ay emerge within the hole. During the film evolution the thickness of the m icrolayer covering the hole remains practically constant due to the "revers e reservoir effect." The total heat flux across the condensate film is foun d to decrease with the absolute value of the condensation constant. When th e solid substrate is tilted, the film dynamics exhibits the formation of mu ltidrop structures and their coarsening along with the stages typical for t he horizontal case. The increase of the tilt angle leads to faster transiti on from dropwise to filmwise condensation and to the increase of the total heat flux through the condensate. (C) 2001 American Institute of Physics.