Transient Response of Straw Filling with Water

[Mindscrape]

Okay, since the most fluids I've studied are from the Euler equation in the context of plasma physics I may be asking a trivial question, but here goes anyway. What I am wondering about is why there is a transient response when I cap a straw with my finger, place the straw in water (while still capped), and then release my finger (while straw fully submerged in water). The water should just fill the straw to the water level, which is what happens in steady-state of course, but I noticed that initially the water in the straw actually goes a bit past the water level of the glass.

I noticed this at a restaurant the other day when I first got my full water glass, and I later noticed when the glass was only 1/3 full, instead of the 7/8 full, that I lost the effect. I couldn't come up with an answer.

 

[Danger]

I've inadvertently noticed that effect as well. All that I can think of is that the upward momentum of the fluid carries it (very temporarily) past the water line. That, in conjunction with the sudden partial vacuum of releasing the previously pressurized air in the straw, might account for it. I don't know what effect the meniscus curve (either regular or reverse) has upon the final appearance.

 

[cjl]

I would imagine it's just the fluid's upward momentum. It reaches the equilibrium level with some remaining upward velocity, and therefore continues briefly past.