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-   -   initial conditions for simulation in rot.fr.ref. (https://www.cfd-online.com/Forums/cfx/19512-initial-conditions-simulation-rot-fr-ref.html)

 Pascale Fonteijn March 7, 2003 12:48

initial conditions for simulation in rot.fr.ref.

Hi all,

I have performed a simulation for a rotating piece of equipment in a stationary frame of reference. For this I have defined an angular velocity on the rotating wall. This gave me a good solution.

Now I would like to perform the same calculations in a rotating frame of reference. Is there a way to use the results of the calculations in the stationary frame of reference as an initial guess for this new calculation? Pressure, temperature and additional varaibles are OK but of course the velocity components are incorrect.

Thanx, Pascale

 Robin March 7, 2003 19:32

Re: initial conditions for simulation in rot.fr.re

Hi Pascale,

You did this in CFX-5?

Robin

 Pascale Fonteijn March 9, 2003 17:31

Re: initial conditions for simulation in rot.fr.re

That is a YES.

Pascale

 Robin March 10, 2003 21:54

Re: initial conditions for simulation in rot.fr.re

Hi Pascale,

Wall boundary conditions cannot enforce flow normal to the wall, regardless of the expression used, only tangential velocities can be specified. Unless your geometry is made entirely of swept surfaces, your initial analysis will be incorrect.

Regards, Robin

 Martin April 30, 2003 04:45

Re: initial conditions for simulation in rot.fr.re

Hi Pascale,

I do not understand your concept of solving something which is moving in a stationary frame of reference. Do you mean that you specified the fluid domain as stationary, and then in the def file you added a parameter for the wall - angular speed ? Is that possible? I wonder what the solution represents.

Anyway, I am myself puzzled about the way CFX treats rotation. Please have a look at my recent post Re: Rotation effects. Your opinion will be appreciated.

Martin

 Pascale Fonteijn May 6, 2003 17:44

Re: initial conditions for simulation in rot.fr.re

Hi Martin,

That is exactly what I did. I have a cilinder that is rotating in a rectangular space. So the space is stationary and the cilinder just has an angular velocity on the outer wall.