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-   -   FROZEN ROTOR IN UNST. SIMULATIONS (http://www.cfd-online.com/Forums/cfx/25819-frozen-rotor-unst-simulations.html)

Spillo May 15, 2008 11:04

FROZEN ROTOR IN UNST. SIMULATIONS
 
Hello,

I'd like to know your opinion about using a frozen rotor interface between a rotor and a stator in a unsteady simulations.

Frozen Rotor option does not change the relative position between the rotor and the stator, so that when passing from one domain to the other the boundary condition for the successive domain never changes. Is it correct?

Does it makes sense in a unsteady simulation? In fact in that way I have that in the frozen rotor interface the solution is time independent.

Thanks,

Luca

wayne May 16, 2008 04:14

Re: FROZEN ROTOR IN UNST. SIMULATIONS
 
yes,it seems to be,so the relative positon have influnce to the result.

Farid May 20, 2008 12:34

Re: FROZEN ROTOR IN UNST. SIMULATIONS
 
Hi, I am also trying to run an unsteady case using frozen rotor. Do I need to set the frame as Rotating frame in Global Initialization?

# I also tried with Transient Rotor Stator model instead of Frozen Rotor model. But in that case it is rotating the rotor domain around the origin(i.e. origin point is the pivot ). But I made the center point of the rotor domain at different location and the pivot should not be the origin in my case.

Is there any suggestion for changing the pivot of the rotor domain?

Thanks

Farid

CycLone May 25, 2008 23:01

Re: FROZEN ROTOR IN UNST. SIMULATIONS
 
Spillo: You can use Frozen Rotor in transient, but you would only do so if you weren't interested in the transient effects around the rotating part, otherwise it is advisable to use Transient Rotor-Stator.

Farid: You have chosen the wrong axis of rotation. If your system does not rotate about a primary axis of the global coordinate system, either create a local coordinate system aligned with the device, move the device to the global system, or specify the axis of rotation about two points.

-CycLone

Farid May 26, 2008 15:04

Re: FROZEN ROTOR IN UNST. SIMULATIONS
 
Hi Cyclone, Thanks a lot.

Spillo May 31, 2008 13:32

Re: FROZEN ROTOR IN UNST. SIMULATIONS
 
Thanks CycLone, what I don't understand is: in all the manuals is said that the relative position between rotor and stator is fixed, but in case I am running an unsteady simulation where the rotor is changing the position at each time step that is not possible since at each instant the position is effectively different...I cannot understand what is going on with frozen rotor interface model...

Cheers

CycLone June 1, 2008 21:05

Re: FROZEN ROTOR IN UNST. SIMULATIONS
 
Hi Spillo,

It is fixed if you use a frozen rotor interface, even in transient. However, if you use a transient rotor-stator interface in transient the relative position at the interface will be updated accordingly.

-CycLone


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