# Simulation CFD

#### How to model an outlet or a bracket with vent holes?

49 Views, 6 Replies
03/06/2018 11:35 PM

Hello,

I usually use the real bracket 3D STEP in my models but I'm wondering if there is another way to model a bracket or an opening with vent holes.   The issue with using the real bracket model is the mezz size can be huge at times depending on the bracket details.  I'm just wondering how I can model something like a bracket and express the area of the vent holes as a percentage of the bracket area for example.

-Long

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Message 1 of 6 ( Views: 49 )

#### Re: How to model an outlet or a bracket with vent holes?

03/07/2018 2:49 AM

Hello Long,

Resistance material defined by free area ration can be used to represent the vent holes as a percentage of the bracket area.

But resistance could not used as an outlet but only can be used inside the model. So I think you need create a virtual outlet after the resistance material

Xiaojin Zhang
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Message 2 of 6 ( Views: 40 )

#### Re: How to model an outlet or a bracket with vent holes?

03/07/2018 8:49 AM

Do you know whats typical FAR for the radial directions of filters?

thanks,
Isak

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Message 3 of 6 ( Views: 35 )

#### Re: How to model an outlet or a bracket with vent holes?

03/07/2018 9:08 AM

Hi Isak,

The free area ratio can be calculated by:

Free area(Total area of all vent holes/Total area

Xiaojin Zhang
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Message 4 of 6 ( Views: 32 )

#### Re: How to model an outlet or a bracket with vent holes?

03/07/2018 9:17 AM

Hi Isak,

The free area ratio can be calculated by:

Free area(Total area of all vent holes)/Total area of the filter.

Xiaojin Zhang
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Message 5 of 6 ( Views: 31 )

#### Re: How to model an outlet or a bracket with vent holes?

03/07/2018 9:38 AM

yes, but in a filter there would also be some flow in radial direction(normal direction 1k and 2k in autodesk cfd). Do you know how to calculate them?

Many thanks!
Isak

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