I am trying to simulate the immediate closing of a valve in a copper pipe having a 2 m column water height in the initial point of the tube. The tube characteristics are: 5 cm diameter and 5 m length. I have chosen a time-dependent analysis considering the gravity and using compressible water for the fluid. I have set a physical time of 5 s with a period of 0.1 s. I use a simple mesh. The boundary conditions that I have established are an inlet volume flow of 1e-5 m^{3}/s and for the other extreme an ideal wall condition.

I have read that there is a relation between the period calculation time (0.1 s for my case), the fluid velocity and the size of one cell of the introduced mesh and I suspect that the problem can be related to that fact. Apart from this, I obtain very strange results so I suspect that I might have also problems when settling the boundary conditions.

Thank you very much for your time,

Pau

this is a fluid structure interaction problem, you are probably better off with a structural code to assess the pipe structure. What do you think a fluid code will tell you? What are you trying to find out?