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h.sanaieian
Posts: 8
Registered: ‎07-25-2013
Accepted Solution

How to create sky in CFD?

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09-24-2013 03:04 PM
Dear all,
 
I am working on ventilation patio I read "the leveraging BIM for CFD modeling "and done exactly like what it said. Create a dome in revite as sky and set temperature on it but have a radiation errors about symmetric pattern.I searched this problem in autodest website but I could not understand what it said.Is it because of dome or the way that I create it? After finish simulation also I had problem with sky because it have not allowed to air go through the building.Would you please help me about this problem?
 
Best Regards,
HANI
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wildej
Posts: 854
Registered: ‎08-25-2011

Re: How to create sky in CFD?

09-24-2013 11:34 PM in reply to: h.sanaieian

Hi,

 

This might be because you are using a symmetry boundary condition possibly?

Is your building sealed or are the external air volumes and the internal one single connected volume?

It might be worth you sharing your CFZ (supprt file) at this stage if you are able.

 

Kind regards,

Jon



Jon Wilde
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Active Member
h.sanaieian
Posts: 8
Registered: ‎07-25-2013

Re: How to create sky in CFD?

09-26-2013 12:38 AM in reply to: wildej

Hi jon,

I really want to send my CFZ file but it is more than 1.5 MB so I can not attach it here.Is there any way for me to send this file(2.5 MB). I have used temperate boundry condition on sky, maybe because of that the software considered it as symmetry boundry condition so how can I set temperature on sky volume?

I have some urban blocks in the middle of dome as the sky and the cubic volume as external air want to find out air movement, temperature and radiation around the urban blocks.

I really thanks you about help.

Best Regards,

Hani

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Product Support
wildej
Posts: 854
Registered: ‎08-25-2011

Re: How to create sky in CFD?

09-26-2013 01:01 AM in reply to: h.sanaieian

I will send you a pm



Jon Wilde
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Product Support
wildej
Posts: 854
Registered: ‎08-25-2011

Re: How to create sky in CFD?

09-26-2013 03:21 AM in reply to: wildej

OK Hani, I have the model, thanks for sharing it.

 

I can tell you that the multiple symmetries are part of what is causing the error but there are many issues with Boudary Conditions - please could you mark up an image of the model, explaining what the goal is, as I cannot interpret it from just the model alone.

 

One thing you should know, is that we cannot assign internal Surface Boudnary Conditions - these all need to go.

 

Kind regards,

Jon



Jon Wilde
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Active Member
h.sanaieian
Posts: 8
Registered: ‎07-25-2013

Re: How to create sky in CFD?

09-29-2013 01:14 AM in reply to: wildej

Hi Jon,

I sent a pdf file for you with wetransfer.

best Regards,

Hani

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wildej
Posts: 854
Registered: ‎08-25-2011

Re: How to create sky in CFD?

10-02-2013 12:07 AM in reply to: h.sanaieian

Hi Hani,

 

Thank you for the file - this is getting there.

 

There is no gain in having an air-dome within a large cuboid though - I suggest you delete the dome and just have a cuboid air domain.

There is no need to apply slip/symm to the walls where you have pressure and velocity - only the side walls where you wish to remove the frictional effects.

 

If you assigning a temperature to the floor - use the entire floor. It is also best to add a thickness to the ground and assign the temp beneath this rather than on top - as right now we are preventing the ground from heating up at all by fixing it's temperature.

 

I hope that helps you move forwards.

 

Kind regards,

Jon



Jon Wilde
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Active Member
h.sanaieian
Posts: 8
Registered: ‎07-25-2013

Re: How to create sky in CFD?

10-02-2013 05:22 AM in reply to: wildej

Dear jon,

Thanks lot for your help.I try and back to you.

Best regards,

hani

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Active Member
h.sanaieian
Posts: 8
Registered: ‎07-25-2013

Re: How to create sky in CFD?

10-02-2013 06:41 AM in reply to: h.sanaieian

Hi Jon,

should I set anything for initial boundry?Is it same as boundry condition?

Kind Regards,

Hani

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Product Support
wildej
Posts: 854
Registered: ‎08-25-2011

Re: How to create sky in CFD?

10-03-2013 06:03 AM in reply to: h.sanaieian

Hi Hani,

 

Nope, just use Boundary Conditions. Initial Conditions are only used for transient analyses, for instance, if we are looking at something heat up over time and wish to set an intial temperature on the volume.

 

Kind regards,

Jon



Jon Wilde
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