get a wind tunnel? really?

3 posts / 0 new
Last post

Hello -

I'm currently looking at building user interfaces to aid in natural ventilation studies using energy plus. In order to use an airflow network you need to input the air pressure coefficients for exterior surfaces at specified wind direction angles.

Sources like the EnergyPlus engineering ref and ASHRAE fundamentals suggest that for non-rectangular buildings either CFD analysis or wind tunnel results are required. They are simultaneously skeptical of CFD results. I have to assume that most people don't have a wind tunnel in their office.

When you have non-rectangular building - where do experienced people go for wind pressure coefficients if you don't have a wind tunnel? Is there a readily available, reasonably easy to use, and reasonably reliable CFD source that you would recommend? Other sources that don't require massive computation time? Tables? Charts? Databases?

thanks in advance,

David Bosworth

Dave Bosworth's picture
Joined: 2011-10-02
Reputation: 0

There are a few software tools available to assist in that regard. I
have made good use of one called TNO CpGenerator
( which has the added advantage of being free.


David Bradley's picture
Joined: 2011-10-01
Reputation: 0

Hi Dave,

This paper describes and compares some sources of Cp data.

C?stola D, Blocken B, Hensen JLM. 2009. Overview of pressure coefficient data in building energy simulation and airflow network programs. Building and Environment 44(10): 2027-2036.

If you don't have access to this journal, you can also download a pre-print version from:

I would also recommend this paper published in the last IBPSA conference, which shows that wind tunnel experiments are more than feasible for large scale projects:

Catherine Simpson; Michael Whalley, DYNAMIC THERMAL MODELLING AND PHYSICAL WIND TUNNEL TESTING, Proceedings of the 11th IBPSA Building Simulation Conference, 27-30 July, 2009.



Costola, D.'s picture
Joined: 2011-10-02
Reputation: 0