<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:st1="urn:schemas-microsoft-com:office:smarttags" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<meta name=Generator content="Microsoft Word 11 (filtered medium)">
<!--[if !mso]>
<style>
v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style>
<![endif]-->
<title>Links between CFD or MZ and thermal simulations for simulating air and
temperature distributions in atria</title>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="country-region"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="City"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="place"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="PersonName"/>
<!--[if !mso]>
<style>
st1\:*{behavior:url(#default#ieooui) }
</style>
<![endif]-->
<style>
<!--
/* Font Definitions */
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Verdana;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman";}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{color:blue;
text-decoration:underline;}
p
{mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman";}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:Arial;
color:navy;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.25in 1.0in 1.25in;}
div.Section1
{page:Section1;}
/* List Definitions */
@list l0
{mso-list-id:550193947;
mso-list-type:hybrid;
mso-list-template-ids:406208628 67698703 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;}
@list l0:level1
{mso-level-tab-stop:.5in;
mso-level-number-position:left;
text-indent:-.25in;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
-->
</style>
</head>
<body lang=EN-US link=blue vlink=blue>
<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Frederik, I have worked on a couple of
large atrium projects over the years. You did ask for comments and suggestions
so here goes:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>You need a tool that can predict
conditions in a quite complicated space and looking at you location you will
have two major problems:<o:p></o:p></span></font></p>
<ol style='margin-top:0in' start=1 type=1>
<li class=MsoNormal style='color:navy;mso-list:l0 level1 lfo1'><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial'>downdraft
and cold radiation during the winter<o:p></o:p></span></font></li>
<li class=MsoNormal style='color:navy;mso-list:l0 level1 lfo1'><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial'>high
radiation surface and possible stratification during the summer.<o:p></o:p></span></font></li>
</ol>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I model the space with ROOM (ARUP Rand D, Mike
Holmes and Andrew White) or lately TRNSYS. This enables me to set up heat balances
and run fairly quickly (once the models have been built), and provide what if
scenarios for both summer and winter. ROOM enables me to look at radiation exchange
in the space and occupant comfort, as well as stratification. TRNSYS will allow
analysis of air movement within the space, this is especially important when
heating the space in winter.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Once these have been completed you can
step to CFD (Colours for Directors), at this point I will probably get shot
down, but most of the CFD programs I know are steady state, so for one moment
in time. The next problem is the complexity of the space, the grids and the
number of cells all of which increase the validity of the results and
drastically increase computational time. For example CFD runs for the atrium in
the LA courthouse were between 56 to 72 hours each.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I think you need to work out what results
you require and the level of accuracy of these results. Is this a design
problem or an academic project?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>We published a paper on temperatures and bulk
air movement for a large atrium in a hospital in the <st1:country-region w:st="on"><st1:place
w:st="on">Netherlands</st1:place></st1:country-region>, which had a large
glazed roof and numerous openings, this was about 15 years ago and is published
in ASHRAE transactions. I also presented a paper on a large atrium/shopping
mall in <st1:City w:st="on"><st1:place w:st="on">Warsaw</st1:place></st1:City>
at the opening of DTU new labs in 2001. The LA courthouse data has never been
published as it is the property of the client, but I may be able to find some
of the results for you. To give you some idea of the costs and time involved for
this particular analysis, the CFD analysis alone was in the order of $120,000
and our effort, temperature, air movement, thermal comfort and stratification
as well as writing a report, that could be understood by the client another
$240,000 and we didn’t make any profit.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I hope this helps, if not let me know what
else you need, good luck.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt'><st1:PersonName
w:st="on"><font size=2 color=black face=Arial><span style='font-size:10.0pt;
font-family:Arial;color:black'>Peter Simmonds</span></font></st1:PersonName><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'>. Ph.D.</span></font><font size=1 color=gray face=Arial><span
style='font-size:7.5pt;font-family:Arial;color:gray'><br>
Senior Associate, Advanced Technology Group<br>
<br>
</span></font><font color=gray face=Arial><span style='font-family:Arial;
color:gray'>IBE Consulting Engineers</span></font><font color=gray><span
style='color:gray'><br>
</span></font><font size=1 color=gray face=Arial><span style='font-size:7.5pt;
font-family:Arial;color:gray'>14130 Riverside Drive Suite 201</span></font><font
size=1 color=navy face=Arial><span style='font-size:7.5pt;font-family:Arial;
color:navy'><br>
</span></font><font size=1 color=gray face=Arial><span style='font-size:7.5pt;
font-family:Arial;color:gray'>Sherman Oaks, CA 91423<br>
p: (818) 377-8220 ext. 246<br>
f: (818) 377-8230<br>
m: (818) 219-1284<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=1 color=gray face=Arial><span style='font-size:7.5pt;font-family:Arial;
color:gray'>This e-mail message, including any attachments, is for the sole use
of the intended recipient(s) and may contain confidential and privileged
information. Any unauthorized review, use, disclosure, or distribution is prohibited.
If you are not the intended recipient, please contact the sender by reply
e-mail and destroy all copies of the original message<o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Frederik Vildbrad Winther (FRW)<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, May 29, 2009 5:17 AM<br>
<b><span style='font-weight:bold'>To:</span></b> bldg-sim@lists.onebuilding.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Bldg-sim] Links between
CFD or MZ and thermal simulations forsimulating air and temperature
distributions in atria</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p><font size=2 color=black face=Verdana><span lang=DA style='font-size:10.0pt;
font-family:Verdana;color:black'>Hi,</span></font><span lang=DA> </span><o:p></o:p></p>
<p><font size=2 color=black face=Verdana><span lang=DA style='font-size:10.0pt;
font-family:Verdana;color:black'>I am currently starting up on simulating a
relatively large atrium in Denmark (app. 55°N) with a glazed roof (sloped
towards the sun - clever), open balconies with working areas connected to the
atrium, as well as a smaller atrium with smaller openings connecting the two
atria together with each other.<b><span style='font-weight:bold'> The main
focus in the simulation is first of all the air velocity and temperature
distribution in the occupied zone and on the balconies - describing the thermal
comfort as well as draft rate.</span></b> The next focus is on integrating the
smaller atria as a heat exchanger in winter time as well as analyzing if this
can be used for cooling in summer time, transporting the air from outside to
the biggest atrium, via the smaller atrium with little heating of the air. The
calculations I want to perform in CFD also regards simulations of the solar
gain in the biggest atrium. However simulating radiation in CFD simulations
require more computing power for bigger rooms with a lot of surfaces. Any
advice on simulating solar gain in CFD? How can this dynamic gain be simulated
in CFD? Another cool thing in this atrium would be the heat recovery of the
extracted air in the top part of the atrium.</span></font><o:p></o:p></p>
<p><font size=2 color=black face=Verdana><span lang=DA style='font-size:10.0pt;
font-family:Verdana;color:black'>Simulating this in a thermal simulation
software requires a lot of luck to obtain the correct (and true) result in the
first couple of simulations. However I am thinking of integrating the results
from a CFD calculation into the thermal simulation. I am thinking of doing this
as an iterative process, integrating the results from CFD when needed in the
thermal simulations. This will probably result in at least 4 different
simulations over a whole year, giving detailed results (temperature gradient,
flow between zones, convective heat-transfer coefficients etc.) which can be used
in the thermal simulation for these 4 periods over a year. As mentioned above
simulating radiation in CFD is tough, I am thinking of leaving this calculation
in the thermal simulation.</span></font><o:p></o:p></p>
<p><font size=2 color=black face=Verdana><span lang=DA style='font-size:10.0pt;
font-family:Verdana;color:black'>Another simpler setup would be the integration
of a multi-zone calculation in the thermal simulation giving a more coarse
result of the main flow route in the atrium and mixing between balconies and
the atrium. However these results could potentially give the same detailed
results I am looking for.</span></font><o:p></o:p></p>
<p><font size=2 color=black face=Verdana><span lang=DA style='font-size:10.0pt;
font-family:Verdana;color:black'>Finally has any one worked on an uncertainty
analysis of these coupling methods illustrating first of all the uncertainty in
the results as well as the sensitivity in the input parameters?</span></font><o:p></o:p></p>
<p><font size=2 color=black face=Verdana><span lang=DA style='font-size:10.0pt;
font-family:Verdana;color:black'>Has anyone done something like this before and
what tools were used? I have been given free hands with regards to choice of
software so any feedback on this subject will be useful. I'm really looking
forward to hear from you :-)</span></font><o:p></o:p></p>
<p><b><font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;
font-family:Verdana;font-weight:bold'>Kind regards</span></font></b><span
lang=DA> </span><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p><b><font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;
font-family:Verdana;font-weight:bold'>Frederik Vildbrad Winther (FRW)</span></font></b><span
lang=DA><br>
</span><font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;
font-family:Verdana'>M.Sc., Indoor Environments</span></font> <br>
<font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;font-family:
Verdana'>Indoor Climate and HVAC</span></font> <br>
<br>
<font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;font-family:
Verdana'>Rambøll Danmark A/S</span></font> <br>
<font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;font-family:
Verdana'>Teknikerbyen 31</span></font> <br>
<font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;font-family:
Verdana'>DK-2830 Virum</span></font> <br>
<a href="http://www.ramboll.dk"><font size=1 face=Verdana><span lang=DA
style='font-size:7.5pt;font-family:Verdana'>http://www.ramboll.dk</span></font></a><span
lang=DA><br>
<br>
</span><font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;
font-family:Verdana'>Direct 4598 6254<br>
</span></font><a href="mailto:frw@ramboll.dk"><font size=1 face=Verdana><span
lang=DA style='font-size:7.5pt;font-family:Verdana'>mailto:frw@ramboll.dk</span></font></a><font
size=1 face=Verdana><span style='font-size:7.5pt;font-family:Verdana'> </span></font><br>
<font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;font-family:
Verdana'>__________________________________________________ </span></font><br>
<font size=1 face=Verdana><span lang=DA style='font-size:7.5pt;font-family:
Verdana'>Knowledge taking people further---</span></font><span lang=DA> </span><o:p></o:p></p>
</div>
</body>
</html>