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Shambav,<br>
<br>
It would be helpful to know more about what you want to achieve with
natural ventilation. In order of precedence:<br>
<ol>
<li>How temperate is the climate? The climate needs to be fairly
temperate. Most of the UK will be ok for natural vent in many
commercial buildings. The same is not true for the South of
France!</li>
<li>How heavily used is the building? Forget natural ventilation
if a building has dense occupancy or high IT loads.<br>
</li>
<li>If rules of thumb are followed (e.g. 5% of floor area
reflected as openable area, thermal mass, floor depth to ceiling
height ratio, glazing!) this is a good starting point for the
design</li>
<li>A zonal (not CFD) model will allow you to assess the
performance of the design against weather data and standards
such as ASHRAE 55. Zonal models are computationally cheaper than
CFD and will help consider strategies such as night time purge
ventilation and optimisation of thermal mass.<br>
</li>
<li>Finally, if you're doing something really unusual or bespoke
(like working for Norman Foster) CFD may be warranted. Boundary
conditions such as surface temperatures and flow through
openings can be extracted from a "snapshot" of the zonal
modelling. You may want to choose more than one design day to
cover variations in climate and use (e.g. still days when there
is little wind to drive ventilation).<br>
</li>
</ol>
Regards<br>
<br>
Chris<br>
<br>
On 10/02/2011 06:05, Cheney wrote:
<blockquote
cite="mid:AANLkTimJQKSp70hSbhn+HX3w1z2dWUCyvP6bR37JgHLB@mail.gmail.com"
type="cite">Hi Sambhav,
<div><br>
</div>
<div>For natural ventilation analysis, you may start with some
field measurements or wind tunnel test which can help you
decide the boundary condition precisely. Some key parameters,
such as prevailing wind direction, representative wind speed,
air temperatures, surface temperatures, etc. are all important
components of the boundary condition. Meanwhile, building
geometry, building materials, surrounding buildings, topography,
etc. may influence the boundary condition significantly. You
will have a holistic consideration of all these variables and
make reasonable simplification to work out the boundary
condition. </div>
<div><br clear="all">
<div><font face="comic sans ms,sans-serif">Regards, </font></div>
<div> </div>
<div><font face="comic sans ms,sans-serif">Cheney</font></div>
<div> </div>
<div><font face="comic sans ms,sans-serif">LinkedIN @ </font><a
moz-do-not-send="true"
href="http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b"
target="_blank"><font face="comic sans ms,sans-serif">http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b</font></a><font
face="comic sans ms,sans-serif"> </font></div>
<br>
<br>
<br>
<div class="gmail_quote">On Wed, Feb 9, 2011 at 8:54 PM, sambhav
tiwari <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:tiwari.sambhav@gmail.com">tiwari.sambhav@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
Hi All,<br>
Does any one know how to model natural ventilation
using cfd<br>
tools like fluent anysis starccm+ etc and what should be
the<br>
boundary conditions applicable for natural ventilation in
room.<br>
<br>
Thanks<br>
Sambhav<br>
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</blockquote>
<br>
<div class="moz-signature">-- <br>
<div>
<p>Chris Yates <span style="color: rgb(79, 98, 40);">C Eng
MCIBSE</span></p>
<p><i style="">Building Physics Consultant<o:p></o:p></i></p>
<p>Tel:<span style=""> </span>+447960731576</p>
<p>Email: <a class="moz-txt-link-abbreviated" href="mailto:chris.malcolm.yates@gmail.com">chris.malcolm.yates@gmail.com</a></p>
<p>Skype: <span class="SpellE">christopher.m.yates</span></p>
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