Hello, I am trying to model the movement of gas or water in a straight pipe which rotates about its axis with constant rate. I have codes for modeling of flows with fixed walls but how to include rotation? Is this task non-stationary or I may use steady state code? Thank.

Hi Leon,

I guess you could solve your problem in the rotating frame of reference of the pipe, then the 'walls' of the pipe in this frame will be fixed. You will have of course to add additional terms to account for the effect of the centrifugal and corioilis accelerations. Whether the flow is in steady state or not might depend on the parameter of the problem (rotational speed, viscousity, ...). I guess that if the flow is laminar, the you probably will have a steady solution, where the time derivatives of the density, velocity and pressure will vanish. If you do have a problem with the additional Coriolis and centrifugal terms, I can try to help, and I am sure there would be other people in the forum who would help. I guess you are writting and solving the equation in a cylindrical coordinate system, with r, theta (or phi) and z, and the pipe is rotating around z. Am I correct?

Cheers, Patrick

[krishns]

Hi,

I'm also facing similar problem. I want to derive an equation for exit velocity from a pipe rotating about an axis perpendicular to its axis. fluid under pressure P1 enters at the inlet. How I can calculate the exit velocity? considering the centrifugal force?
Kindly help me

Krish