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-   -   Can CFX do CHT simulations with a solid domain rotating in a stationary fluid domain? (http://www.cfd-online.com/Forums/cfx/71556-can-cfx-do-cht-simulations-solid-domain-rotating-stationary-fluid-domain.html)

acro January 7, 2010 11:36

Can CFX do CHT simulations with a solid domain rotating in a stationary fluid domain?
 
I tried to rotate a solid impeller in a stationary fluid domain. What's I am trying to do is that the solid impeller rotates by itself and pushes the surrounding fluid.

I set the the solid impeller as a rotating domain, and the fluid as a stationary domain. And tried various options for the interface between solid and fluid. But none of them worked.

Could anybody guide me? Thanks a lot.

Attesz January 7, 2010 13:20

Hi,

I think it will not working. You have do define the fluid as a rotating domain, to set to the flow tangencial velocity component. But why do you want to do your simulation this way? Wit rotating domain option, you can get very accurate results, with transient simulation you can set "Transient Rotor Stator" Frame Change model, which "rotates" the domain...

Attesz

acro January 7, 2010 16:13

Quote:

Originally Posted by Attesz (Post 241807)
Hi,

I think it will not working. You have do define the fluid as a rotating domain, to set to the flow tangencial velocity component. But why do you want to do your simulation this way? Wit rotating domain option, you can get very accurate results, with transient simulation you can set "Transient Rotor Stator" Frame Change model, which "rotates" the domain...

Attesz

Thanks for your reply.

What you suggested is: set the fluid as a rotating domain. How about the solid domain? stationary or rotating? Do I need to make some settings to the interface?

Now that CFX can set a solid as a rotating domain, I suppose this option is somehow useful. But if I set solid as rotating domain and fluid as stationary domain, it turned out that the solid rotation has no effect on the fluid flow. I guess I might miss some settings?

stumpy January 7, 2010 17:53

Rotating solid domains essentially add a rotational advection term to the energy equation in the solid domain, so they are only needed when you need to account for the advection of energy due to the rotation of the solid domain (e.g. a brake disk). In your case just use a rotating fluid domain and a stationary solid domain.

Attesz January 7, 2010 17:57

The solid domain is useful, when you want to take into account the heat transfer for example. Of course, you have to make it rotating. But this rotation will not rotate the flow, you have to define it separately. Otherwise, in first step, you should simulate only the flow field. Taking into account of the solid body is a refinement. The walls of the rotating body will be set rotating. If there are standing walls in the rotating body, you have to set them "Counter Rotating Walls". But I think, there is a good tutorial about it in CFX help!

Good luck,
Attesz

acro January 7, 2010 18:49

Thank Attesz and stumpy. I asked questions in other forums, but never got quick answers like here. I appreciate your kind help very much.

Back to my question.

My goal is to simulate a solid impeller pushing liquid. But what you suggested is to make the liquid rotating by itself. Sounds like different from the original problem. Can this kind of simulation give me accurate flow pattern just like the stationary liquid is pushed by a rotating impeller?


By the way, I do need to do conjugate heat transfer. The impeller (actually it's not a real impeller, just some solid bodies with irregular shape) generates heat.

Attesz January 7, 2010 18:57

This kind of simulation is the general method for modelling rotating things. I"ve never heard, and I've got absolutely no idea how to do that, what do you want!
If the solid body has effect to the flow, then model it, but note, that you need more cells.

Otherwise, I'm simulating now an RC quad rotor helicopter's propeller. We have measures for the trust, and the difference between CFD and measure is very small. We made the simulation before, to check the goodness of the propeller blades, and after that we measured them. Without solids. But by using rotating fluid domain, like we said.

Regards,
Attesz

Omid July 8, 2013 00:43

how could i merge two domains in one simulation?
 
Hi buddies
I want to simulate a simple physic environment, in which one's outlet would be another's inlet, the first's outlet flow will receive to second domain after about 20 seconds, how could I define this correlation?
Regards,
Omid.

ghorrocks July 8, 2013 08:11

Periodic boundaries can do it - but not with a time delay.


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