Dear all:

I have a tough question about calculating fluid velocity in pipe. The thing
is like this: fluid is flowing with a average velocity v in a pipe pushed by
external force.  there is a periodically open and close valve applied on the
pipe. obviously, when the valve closed rapidly, the flow is stoped and
pressure rises. And, when the valve is open, the flow velocity will go much
higher than average velocity v immediately and then fades to the v .I think
it is not so difficult to picture how the flow is going on. My problem is to
mathmatically express the whoe process instead of simulating it with ANSYS.

Thanks for any help!

David