The setting is as follows. A hollow pipe (flooded) with radius R-pipe is being lifted from below the water surface (totally submerged) to above the water surface with a speed of v1. The pipe is closed at the top and the bottom. The crane that is lifting the pipe does not want to lift the water that is inside the pipe as well. What size holes (how many) do you have to drill at the top of the pipe and the bottom of the pipe so natural flow through the pipe occurs (if this even does occur)?
Also, when the pipe is being lifted from the water (so while a part is still in the water) you don't want the water level in the pipe to be higher than the level of the water surface (you don't want to lift the extra kilo's). I thought this was the case:
But I think there is something wrong. So how big should the hole at the top and bottom be related to the lift speed and the height between the two holes so water flows through the pipe? Does water even flow through when the holes are in the side of the pipe?