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[MadScientist]

Hello,

I'm trying to model internal fluid flow of a DC fan in a box. I downloaded the CAD model, cleaned it up to have less than 300 faces, and I created a box around it to pump air into, When I try to extract the volume, I see that it is not considering a subpart of it at all in the final enclosed volume.

This is the result on Preview Inside Faces. The central rotor is not in red, which it should have been. I have selected the outer edge loops of the box for the enclosed region.

I checked the geometry of the rotor and it said that it doesn't have any errors. Also I want the fan seperate so that I can use it as a rotating mesh.

Is this some limitation of the student version? I don't get any warnings on save.

Thank you!

 

PS, I have attached the file

[Karthik Remella]

Hello,

As of 2020 R1, you cannot run MRF or rotating mesh simulations in Discovery Live. Please use Ansys Fluent instead to run these kind of simulations.

Thank you.

[MadScientist]

Thanks for the reply.

Yes, I don't have much hope for rotating wall for that fan. But regardless, shouldn't that fan have been enclosed?

Also, what's the rotating wall useful for, then?

[Karthik Remella]

Hello,

Rotating Wall sets a rotating wall on the selected face. This boundary condition can be used to simulate rotating parts without the parts physically moving. The solver uses Rotating Wall to mathematically apply the rotation. It sets an angular velocity to the part.

Please see this video to understand the capabilities.

https://youtu.be/36KCD-OFTNc

Thanks.

Best,

Karthik

[MadScientist]

Ok, I accept that. But why isn't the fan being extracted so that I can atleast do this in fluent?

[Karthik Remella]

When you perform check geometry in SCDM, do you see any errors in it? In SCDM, you should be able to right-click on the part and you should see the option there.

 

[MadScientist]

No errors.

[Karthik Remella]

Interesting! 

The central region not showing entirely might be the culprit. Could you see if you are able to remove the central region completely and try to extract the volume? This would at least narrow it down to this. Let me know what you find.

[MadScientist]

Sorry for the late reply. I was caught up with doing this in Fluent, that I didn't have time for this. What do you mean by removing the central region?

[Karthik Remella]

I meant, remove the portion which is incomplete and re-create the piece from scratch. Maybe that will take care of the issue?

[MadScientist]

The model itself is like that.

[Karthik Remella]

If I understand right, the original CAD model had this small missing portion. Is this how your CAD for the fluids simulation supposed to be? Or this region is something which is not of interest and you really don't need to have this as part of the simulation?

This seems odd that your CAD model does not have the full cover of the fan. I cannot guarantee, but in my experience, when you have such abnormalities in the CAD, rebuilding the portion of the CAD has helped.

Anyways, I'm guessing that you are able to get this model working in Fluent. Right?

Thanks.

Karthik

[MadScientist]

The CAD file which I downloaded itself is like that. But yes, nevermind. I simulated it in FLUENT. Now I'm approximating it using swirling flow in Discovery Live.

[Keyur Kanade]

sometimes extract volume fails for some bodies. in this case you have couple of options. 

1. merge all solids using combine tool and then use volume extract

2. use volume extract. then use combine tool to subtract fan body from fluid body. 

 

Regards,

Keyur

 

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