Overlapping Rotating Domain

yusofharun · October 13, 2015, 23:21

Greetings to all, bowing to the Super-Mod, Mod, Senior

I have two auger/screw conveyors counter-rotating in a fluid domain. I applied the MFT technique as suggested in Tutorial 17 (Multiphase Flow in a Mixing Vessel). According to this tutorial, stationary domain and rotating domain need to be created.

Since I have 2 moving parts, namely Screw 1 and Screw 2, I have created 2 rotating domains and several interfaces to connect these rotating domains to the stationary domain. The two screws are placed in an intermeshing configuration. Therefore, there is an overlap between the screws’ rotating domains (photo attached)

My concern - Is such setup acceptable?

I have tried running the simulation without making further adjustment on the basic/default setup in CFX-Pre and surprisingly, there was no error/conflict detected. THIS SCARES ME.

Please help me to configure this setup.

bolus13 · June 10, 2016, 05:21

Hi Yusofharun,

Did you eventually manage to solve this problem or is it still scaring you?

I also want to do an analysis with overlapping rotating domains and thinking about a similar setup as you are using. I am also suprised that this worked in your case.

Could you share your epxerience?

Thanks!

urosgrivc · June 10, 2016, 07:38

I am quite interested in this topic asweal. I saw that the newest fluent has an exelent solution for problems with overlapping meshes. But I dont know how CFX handles them

ghorrocks · June 10, 2016, 07:55

In CFX the overlapping domains will simply be modelled as if they are separated. You cannot connect them so the results will be rubbish.

I can think of two methods to model this:
* Immersed solids - this is by far the easiest, but the immersed solids technique is not applicable to all forms of flow so be careful of that.
* Dynamic remeshing - this is trickier as it couples in the pre-processor, but will allow you to run with no physics restrictions.

I am not sure what Fluent supports with overlapping meshes, but CFX definitely cannot do overlapping meshes. At least not yet

urosgrivc · June 10, 2016, 08:40

Althoe this is more for a fluent forum, as cfx doesent suport this but it is interesting anyway

-> https://www.youtube.com/watch?v=NVRh99j1P1Y <- This is probably what you try to model
-> https://www.youtube.com/watch?v=vT8kFjDK_SI <- This is what i ment with a good solution by fluent (as dinamic remeshing is computationaly expensive)

https://www.sharcnet.ca/Software/Ans...c_overset.html

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June 10, 2016, 05:21		#2
bolus13 Member Ruud Caljouw Join Date: Dec 2012 Posts: 45 Rep Power: 13	Hi Yusofharun, Did you eventually manage to solve this problem or is it still scaring you? I also want to do an analysis with overlapping rotating domains and thinking about a similar setup as you are using. I am also suprised that this worked in your case. Could you share your epxerience? Thanks!

June 10, 2016, 07:38		#3
urosgrivc Senior Member urosgrivc Join Date: Dec 2015 Location: Slovenija Posts: 365 Rep Power: 11	I am quite interested in this topic asweal. I saw that the newest fluent has an exelent solution for problems with overlapping meshes. But I dont know how CFX handles them

June 10, 2016, 07:55		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,716 Rep Power: 143	In CFX the overlapping domains will simply be modelled as if they are separated. You cannot connect them so the results will be rubbish. I can think of two methods to model this: * Immersed solids - this is by far the easiest, but the immersed solids technique is not applicable to all forms of flow so be careful of that. * Dynamic remeshing - this is trickier as it couples in the pre-processor, but will allow you to run with no physics restrictions. I am not sure what Fluent supports with overlapping meshes, but CFX definitely cannot do overlapping meshes. At least not yet

June 10, 2016, 08:40		#5
urosgrivc Senior Member urosgrivc Join Date: Dec 2015 Location: Slovenija Posts: 365 Rep Power: 11	Althoe this is more for a fluent forum, as cfx doesent suport this but it is interesting anyway -> https://www.youtube.com/watch?v=NVRh99j1P1Y <- This is probably what you try to model -> https://www.youtube.com/watch?v=vT8kFjDK_SI <- This is what i ment with a good solution by fluent (as dinamic remeshing is computationaly expensive) https://www.sharcnet.ca/Software/Ans...c_overset.html