<html><div style='background-color:'><P>Ian,</P>
<P>In my experience using a thin surface with perforations works well, depending on the software you use. My experience is based on Flovent which allows a perforated plate to be directly modeled. Looking at the openess characteristics and free area ratio of the insect screen type proposed you can get good results. I was able to account for a perforated face diffuser in Flovent.</P>
<P>The other option is to model a thin "resistance" in the air-stream but have not tried it.</P>
<P>Hope this is helpful.</P>
<P>Vaibhav Potnis <BR></P>
<DIV><FONT style="FONT-SIZE: 11px; FONT-FAMILY: tahoma,sans-serif">Senior Associate</FONT></DIV>
<DIV>Green Building Services, Inc.</DIV>
<DIV>Portland, OR</DIV>
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<P>From: <I>"Ian Doebber" <Ian.Doebber@arup.com></I><BR>Reply-To: <I>Ian.Doebber@arup.com</I><BR>To: <I><bldg-sim@gard.com></I><BR>Subject: <I>[bldg-sim] Insect screens on restricting flow</I><BR>Date: <I>Wed, 11 Jan 2006 14:28:48 -0800</I><BR><BR></P>
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<P><FONT face=Arial size=2>I'm concerned about insect screens affecting the buoyancy driven airflow for a double skin façade. I was wondering if anyone new of some papers that have covered the airflow properties of insect screens or can give me some information off hand. I'm also wondering how to incorporate their effects on the flow by use of discharge coefficients and pressure loss coefficients. </FONT></P><BR>
<P><FONT face=Arial size=2>Thanks</FONT> </P>
<P><FONT face=Arial size=2>Ian Doebber</FONT> <BR><FONT face=Arial size=2>Graduate Mechanical Engineer</FONT> <BR><FONT face=Arial size=2>Arup</FONT> <BR><FONT face=Arial size=2>901 Market Street Suite 260 San Francisco CA 94103</FONT> <BR><FONT face=Arial size=2>tel: 415-946-0292</FONT> <BR><FONT face=Arial size=2>fax: 415-957-9096</FONT> <BR><FONT face=Arial size=2>cell: 415-613-4314</FONT> <BR><A href="mailto:ian.doebber@arup.com"><U><FONT face=Arial color=#0000ff size=2>ian.doebber@arup.com</FONT></U></A> <BR><A><U><FONT face=Arial color=#0000ff size=2>www.arup.com</FONT></U></A> </P><PRE>____________________________________________________________
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