Water Dynamics
Most recent answer: 07/04/2009
- B. B.
Great question.
I don't think the interaction with the other fluid, air, has a big effect in this case. The most likely reason is that the flow through the nozzle is fast enough to go turbulent. In turbulent flow, small deviations of the velocity of parts of the fluid from the average actually pick up energy and grow a bit, so that the flow is a mixture of a range of velocities, in a random-looking pattern. Turbulence is driven by the differences in flow speed that are found, for example, between the middle and the edges of the nozzle. Once you have turbulent flow, there will be bits of fluid heading every which-way, and some of them will fly apart from the main stream.
If I'm right, then if the flow is slow enough the spray will stop because the flow will cease to be turbulent. Wikipedia has a discussion of the 'Reynold's number', which determines whether or not turbulence occurs.
Mike W.
(published on 07/04/2009)