Dissolution And Rise Velocity Of Small Air Bubbles In Water And Salt Water

Richard Detsch and Isaac Harris Naval Coastal Systems Center Code 2140 Panama City, FL 32407-5000 The terminal rise velocities of 20-1000 micron diameter air bubbles were measured in water, tap water, and sea water. The measured rise velocities in all three liquids, for bubbles having Reynolds number less than one, agrees well with Stoke's theory for solid spheres. Present results for larger bubbles, in sea and tap water, agree well with earlier data for solid spheres. The data for larger bubbles in water is similar to that in sea water for diameters less than 450 microns, but, begins to agree with a theory developed for clean bubbles at larger diameters. Apparently enough impurities were present in the sea and tap water samples to effectively freeze the bubble surfaces, for all the diameters tested. The dissolution rate for 20-500 micron air bubbles in water and sea water, at 50 and 100% air saturation, is also presented. The data indicate a that the dissolution rate is independent of diameter for bubbles larger than about 70 microns ; but, becames strongly dependent on diameter for smaller bubbles. The rise velocity data was used in conjunction with Levich's Dirty Bubble Formula to predict the dissolution rate of the bubbles. The theory agrees well with the present data forbubbles in saturatedliquids, orwithdiameters larger than 70 microns. Agreement is fair for smaller bubbles in 50% saturated water or and sea water.