Dear Viktor and Macro:
   Thanks for your kind help, but in COMIS 3.1 User guide, I've found the following instructions in "&-WI (Windows and Doors)" :
  
Slanted windows may only be of LVO type 1, 4 and 5. For slanted windows (e.g. windows in a roof)
the Own Height Factor (see figure 4.8), which is the cosine of the angle between the window plane
and a vertical plane, must be given in &-NET-LINks (see page 100).With this factor the program will
calculate the start height and the height of the opening in order to get the correct stack pressure
difference profile. For calculating the area of the opening, the Own Height Factor will not be
taken into account because the flow is assumed to be perpendicular to the opening plane. With
this definition it is even possible to input an opening which is horizontal (Own Height Factor = 0).

   That means it is possible to model horizontal windows in COMIS and I did my modelling in that way to simulate the atrium and the answer from COMIS seems reasonable, how do you think?

Best Regards,
Peng

At 03:44 AM 3/10/2007, Viktor Dorer wrote:

Dear Xu Peng

As mentioned by Marco, horizontal large openings are not included in
COMIS (yet).
I suggest to link the three atrium layers with normal crack links, but
assuming very low resistance, thus high C value and an exponent of 0.5

Any vertical temperature changes in the atrium can be considered in the
input temperature in the additional nodes.

Kind regards
Viktor Dorer

 

_______________________________________

Viktor Dorer
Dipl. Ing. ETH / ASHRAE, SAMPE
Head Energy Supply Technologies Group
Building Technologies Laboratory (118)
Empa - Materials Science & Technology
Ueberlandstrasse 129
CH-8600 Duebendorf  Switzerland

Tel    +41 44 823 42 75 /   or ... 55 11
Fax   +41 44 823 40 09
viktor.dorer@empa.ch
www.empa.ch

>>> Peng Xu <p.xu4@pgrad.unimelb.edu.au> 02.10.2007 08:45 >>>
Dear "COMIS" users:
  I am now trying to simulate the air-flow in an office building with
an
big atrium in the middle, with TRNSYS and COMIS. Because of the high
height and the temperature difference within the atrium, I divided the
atrium vertically into 3 zones, linking them with big openings as if
they
are fully linked and my concentrations for temperature will be on the
lowest level only.
  But I got some strange answers from COMIS when I use the "large
opening"
air flow model between the zones of atrium. In my model, the offices
around the atrium will be mechanically ventilated and the atrium will
be
ventilated through adjacent air flows from the surrounding offices and
the air can be exhausted at the top of the atrium. I am not sure how
to
make such model with both mechanical ventilation and buoyancy
dominated
natural ventilation.
  My concept for this study is hybrid ventilation. The external vents
for
offices would be on when conditions for natural ventilation are met. I
am quite appreciated if I can get help you and a sample COMIS .cpf
file
for the atrium or solar chimney will be highly useful for me to
understand.
  Thanks very much in advance!

Best Regards,
Vince XU
the University of Melbourne,
Melbourne, Australia

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Department of Civil & Environmental Engineering
The University of Melbourne
Victoria 3010 AUSTRALIA
~~~~~~~~~~~~~~~~
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The Department of Civil & Environmental Engineering
Office: (03) 8344 0193 (UNIV MELB)
        (03) 9252 6461 (CSIRO)
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