Volume 9 Issue 3
Effects of Salinity on Bubble Cloud Characteristics
Magdalena D. Anguelova and Pablo Huq
1Remote Sensing Division, Naval Research Laboratory, Washington, DC 20375, USA
2College of Earth, Ocean, and Environment, University of Delaware, Newark, DE 19716, USA
*Author to whom correspondence should be addressed.
Abstract
A laboratory experiment investigates the influence of salinity on the characteristics of bubble clouds in varying saline solutions. Bubble clouds were generated with a water jet. Salinity, surface tension, and water temperature were monitored. Measured bubble cloud parameters include the number of bubbles, the void fraction, the penetration depth, and the cloud shape. The number of large (above 0.5 mm diameter) bubbles within a cloud increases by a factor of three from fresh to saline water of 20 psu (practical salinity units), and attains a maximum value for salinity of 12–25 psu. The void fraction also has maximum value in the range 12–25 psu. The results thus show that both the number of bubbles and the void fraction vary nonmonotonically with increasing salinity. The lateral shape of the bubble cloud does not change with increasing salinity; however, the lowest point of the cloud penetrates deeper as smaller bubbles are generated.
Keywords:bubbles; bubble clouds; seawater salinity; surface tension; whitecaps; breaking waves; plunging water jet; air entrapment; gas exchange; energy dissipation