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saurus January 26, 2011 16:35

User Defined Profiles, Swirl, Velocity Inlet
I've been trying to simulate the flow in a domain consisting of a large cubical volume with a channel in the bottom that is at some angle to the flow. The channel stretches from the inlet to the outlet. I expect the flow in the channel to eventually reach something like helicoidal flow.

Because I want to know something about the streamlines of the flow when it is fully developed, I have been running the simulation with a uniform velocity inlet, and then writing the outlet velocities and turbulence parameters to a profile file, then I have been using these as part of a user defined profile for the inlet of a subsequent run.. repeat, repeat.

I noticed that in each run, the flow would begin in the x-direction (normal to the inlet) and then begin to develop into a helicoid. I read that when using cartesian coordinates for a velocity inlet boundary condition, Fluent dots the velocity profile with the normal, which explains why my y and z velocities are kind of getting washed away, however I was wondering if there is any way around this? I've tried saving the velocities in cylindrical coordinates (v_theta should allow some "swirl", right?), however then my results are really nonsense, and the simulation doesn't converge.

Any insight to a better way to initialize swirl-like flow in a non-symmetrical volume, or any other help would be greatly appreciated.

If I wasn't clear or if you need more information, please don't hesitate to ask, first time posting here, it's hard to spell this stuff out!

Thank you.

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