#Mathstodon, can can we figure out the #physics behind this?
At Alnwick Gardens, the water feature #wateglass shows some mysterious behaviour. The water falls from a circular basin, forming a vertical sheet that oscillates towards the bottom. This flutter is surprisingly aggressive and persistent. It disappears when the water flow is disturbed at the top, but when the disturbance is removed the oscillations quickly grow again.
The plaque attributes the phenomenon to pressure differences between the sides of the sheet of water. While I think it's plausible that the oscillation is indeed an aerodynamic effect, this is not a satisfactory answer without an explanation of why the pressure difference occurs.
It may be relevant that the sheet is curved, because the flutter seems much weaker near the edges of the installation. Could the surface tension be pulling the sheet inward, somehow getting into a positive feedback loop with aerodynamic forces? Your guess is as good as mine...