EFFECTS OF GRAVITY ON REWETTING OF CAPILLARY GROOVE SURFACE AT ELEVATED-TEMPERATURES - EXPERIMENTAL AND THEORETICAL-STUDIES

Theoretical and experimental investigations of the rewetting character istics of thin liquid films over heated and unheated capillary grooved plates were performed. To investigate the effect of gravity on rewett ing, the grooved surface was placed in upward and downward-facing posi tions. Profound gravitational effects were observed as the rewetting v elocity was found to be higher in the upward than in the downward-faci ng orientation. The difference was even greater with higher initial pl ate temperatures. With either orientation, it was found that the rewet ting velocity increased with the initial plate temperature. But when t he temperature was raised above a rewetting temperature, the rewetting velocity decreased with the initial plate temperature. Hydrodynamical ly controlled and heat conduction controlled rewetting models were the n presented to explain and to predict the rewetting characteristics in these two distinct regions. The predicted rewetting velocities were f ound to be in good agreement with experimental data with elevated plat e temperatures.