flow in cylinder
 

Hi every body!

I would be so thankful if any body could help me about the physical solution of

in-compressible flow in cylinder.

a flow is at rest in the initial and suddenly a piston at left end of cylinder starts

to move with constant speed of Vpiston, what would be velocity and pressure values in cylinder?

I would expect that the entire column of fluid would instantly start moving with the piston at a velocity Vpiston (because of incompressibility) and a slug profile. Over time a fully-developed profile would develop ahead of the piston. Look at the problem in the frame of the piston. Then the cylinder would start moving toward the piston with a velocity -Vpiston.

it seems that your comment is correct, but when I want to solve it numerically with control volume scheme it takes time to reach the constant velocity, and it doesn't instantly moves to answer, I would be thankful if you could help me