[Bldg-sim] IES CFD Modeling Issue: Reverse Flow through Diffusers

[JRR]

Hi;

The flow volume vs output pressure of the flow source is critical in 
these cases.
Are you modeling   1) Open bladed fans, 2) Tub

Brain, Joshua wrote:

>Hello,
>
> 
>
>I am using IES to conduct a CFD model on a long and narrow room (283ft
>by 60ft) with three large ducts (square 4ft by 4ft) running along the
>ceiling (280ft long, 28ft off the floor). I have 18 diffusers equally
>spaced along each of the three 280ft ducts for a total of 54. Each
>diffuser has a CFM of 1110, an area of 3.75 sf, and a discharge velocity
>of 300 fpm. There is a single return grill at one end of the building. 
>
> 
>
>My problem is: when I look at the velocity vectors in the MicroFlo
>Viewer some of the diffusers have the air flowing backwards or into the
>diffuser, not flowing out as it is supposed to. This occurs across all
>three duct lengths at the same diffuser location. 
>
> 
>
>Has anyone else run into this and have they resolved the issue?  IES
>took my model and made changes to it only to find that they could not
>fix it. 
>
> 
>
>Thank you in advance for any advice, 
>
>Josh
>
> 
>
>Joshua Brain
>
>Mechanical Group 
>
>R.G. Vanderweil Engineers, LLP 
>
>274 Summer Street     Boston, MA  02210 
>
>Tel: (617) 423-7423 
>
>Fax: (617) 423-7401 
>
>Direct: (617) 956-4565 
>
> 
>
>www.vanderweil.com 
>
> 
>
> 
>
>
>  
>
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>
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