MODELING BUBBLE AND DROP FORMATION IN FLOWING LIQUIDS IN MICROGRAVITY

A theoretical model for the process of bubble and drop formation in fl owing liquids, applicable for both terrestrial and microgravity enviro nments, has been developed by using a force balance. The contact angle variation at the nozzle due to the bubble motion and the added mass c oefficient of the bubble moving through a pipe have been theoretically analyzed, considering bubble motions during its expansion and detachm ent stages. Predictions of bubble size of the model show satisfactory agreement with available experimental results in the case of normal gr avity. The effects of the nondimensional variables on bubble and drop size are evaluated in microgravity conditions. In microgravity, the bu bble is detached from the nozzle only by the liquid flow drag, and in the region of low liquid velocity the bubble size becomes much larger than that in normal gravity.