Reducing Viscous Drag using Microbubbles

David Walkenhorst

A water flow tank was designed and built, in which the force on a model boat was studied. This model boat utilizes a Gore-Tex sock as an outer membrane. Both nitrogen and helium are bubbled through this membrane, and the effect of the force is examined when water flow is on and off, and different gas flow rates are also used. Experimentally, the viscous drag using helium was found to be 23±4.3% less than the viscous drag when nitrogen was used. A second data set confirmed this result, finding that the viscous drag using helium was 25±4.3% less than the viscous drag when nitrogen was used. The construction and use of the model boat and flow tank are described in detail.