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Re: [EnergyPlus_Support] Cp: wind pressure coefficient
Hi,
I know that the EnergyPlus uses the formula of Sawmi and Chandra (1988) to calculate wind pressure coefficient values. But, this equation has a G value (Natural log of the ratio of the width of the wall under consideration to the width of the adjacent wall) which I could not find in the ASHRAE Fundamentals Handbook 2001 - Cap26 ? page 26.6 ? equation 19 and also in ASHRAE Fundamentals Handbook 2005 - Cap27 ?page 27.6 ? equation 19.
Why does EnergyPlus use this G value and the ASHRAE equations not???
Thanks for all,
Ana Paula.
Lixing Gu <gu@xxxxxxxxxxxx> wrote: Ana:
EnergyPlus uses the formula of Sawmi and Chandra (1988), which is the
equation in the Engineering Reference on page 387. The equation uses G. I
compared the equation with the original paper and found both are the same.
I tried to find the equation in Ch 26 of 2001 HOF and Ch 27 of 2005 HOF and
could not locate the equation. Please let me know what specific equation you
refer, equation number and page number.
Thanks.
Lixing
----- Original Message -----
From: "Ana Paula Melo" <apaula_melo@xxxxxxxxx>
To: "EnergyPlus Support" <energyplus_support@xxxxxxxxxxxxxxx>
Sent: Friday, February 22, 2008 8:50 AM
Subject: [EnergyPlus_Support] Cp: wind pressure coefficient
Hi,
I would like to know about the Cp = Wind surface pressure coefficient.
I read in the Enguneering Reference that the EnergyPlus uses the formula
of Sawmi and Chandra (1988) to calculate wind pressure coefficient values.
The equation has a G value (Natural log of the ratio of the width of the
wall under consideration to the width of the adjacent wall).
I looked at ASHRAE Fundamentals Handbook 2001 - Cap26 and I noticed that
the formula to calculate wind pressure coefficient values is different.
Also, I looked at ASHRAE Fundamentals Handbook 2005 - Cap27 and it is
different too as it does not have this G value.
What is the real formula that is used by EnergyPlus and Why???
Thanks for all,
Ana Paula.
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