<HTML><BODY>   <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">Hi Mostapha</span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d"> </span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">in additio! n to the below, I think your approach with only one zone having external openings may be a general problem. The flow simulation can't really solve this, I think, because what you have is a possible flow path chain >in< the atrium (which is basically set up very good, I would think) which is singularily connected to the outside. Remember that one zone node can have only one temperature / pressure at one time step.</span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d"> </span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">Also, I would expect such a large atrium to have >some< leakage in the lower floor (entrance door etc.).</span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d"> </span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">Possible measures: </span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">a) Split the topmost zone into two (or three) that each have a connect to an exterior node</span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">b) also split the lowermost zone into two</span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">c) as written below, add some leakage to the lowermost zone</span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d"> </span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">Do the thermal results seem plausible? Do you have a "nice temperature stack" in the stacked zones?</span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d"> </span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">Best</span></p> <p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: #1f497d">Achim</span></p> <br /><br />--------- Original-Nachricht --------<br /> Von: "Achim Geissler" <achim.geissler@intergga.ch><br /> An: "Mostapha Sadeghipour" <sadeghipour@gmail.com><br /> Cc: "Aizaz Samuel" <aizaz.a.samuel@strath.ac.uk>, esp-r@lists.strath.ac.uk<br /> Betreff: [esp-r] Re: Zero Stack Pressure<br /> Datum: 09/06/10 23:13<br /> <br /> Hi Mostapha<div><br /></div><div>looking at your .a! fn, I think the problem is that all your connections to external nodes are in one zone (01).</div><div><br /></div><div>To get an afn up and running, a basic requirement is that for every zone you can go from an external node to a zone ... to >the< zone ... to a zone ... and so on and then to a (different) external node again. I think this does not hold for your afn. Add a connection type "tiny", e.g. a crack a factor 10 or 100 smaller than your _crk types and connect the lowermost zone(s) to an additional external node.</div><div><br /></div><div>Then something should happen and there should be pressure differences.</div><div><br /></div><div>Best</div><div>Achim</div><div><br /></div><div><br /></div><div><br /></div><div><br /><div><div>On Jun 9, 2010, at 2:47 PM, Mostapha Sadeghipour wrote:</div><br /><blockquote>Hello Aizaz,<br /><br />I think the problem is not the node heights in my case, however I'm not sure. The .afn file is attached.<br /><br />Regard! s,<br /><br />Mostapha Sadeghipour<br /><br /><div class="gmail_quote">On Wed, Jun 9, 2010 at 3:54 PM, Aizaz Samuel <span><<a href="mailto:aizaz.a.samuel@strath.ac.uk">aizaz.a.samuel@strath.ac.uk</a>></span> wrote:<br /> <blockquote style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid #cccccc; padding-left: 1ex">Look up how node heights are defined in exemplars>network<br /> ventilation>alternative facade vent.....<br /> <br /> Theory can be found in Jan Hensen's thesis (section 4.3.2) available at<br /> <a href="http://www.esru.strath.ac.uk/publications.htm" target="_blank">http://www.esru.strath.ac.uk/publications.htm</a><br /> --<br /> Dr Aizaz A Samuel<br /> Department of Mechanical Engineering<br /> University of Strathclyde<br /> M324 James Weir Building<br /> 75 Montrose Street<br /> Glasgow, UK<br /> G1 1XJ<br /> <br /> T:+44 141 548 5765<br /> F:+44 141 552 5105<br /> <div><div class="h5"><br /> On Wednesday 09 June 2010 11:28, Mostapha Sadeghipour wro! te:<br /> > Dear esp-r users,<br /> ><br /> > I'm modeling an atrium with a closed glass roof. The atrium has nearly 16m<br /> > height and it only connects to the outside through 3 cracks on the roof. I<br /> > divided the atrium into 5 vertical zones, and adjacent vertical bypass<br /> > zones. They are connected to each other through fictitious faces.<br /> ><br /> > Common orifice components connect zone nodes to each other vertically, and<br /> > door component connects zone nodes to bypass nodes horizontally. The<br /> > attached image shows the Air Flow Network in my model more clearly.<br /> ><br /> > I supposed that esp-r includes the stack effect whenever delta height<br /> > between the nodes and the component is not zero. So I expected to have a<br /> > stack pressure in the vertical connections. But when I check the results<br /> > the stack pressure in the connections are zero!<br /> ><br /> > I'm also curious! how esp-r consider the stack effects and the gravity? The<br /> > components dP are set manually and there is no "g" in the equations? Where<br /> > I can find the PSTACK equations that is used to calculate DP:<br /> > DP=PRES(IDPS)-PRES(IDNE)+PSTACK(ICNN).<br /> ><br /> > Thanks in advance.<br /> ><br /> > Mostapha Sadeghipour<br /> <br /> </div></div></blockquote></div><br /> <span><atr.afn></span>_______________________________________________<br />esp-r mailing list<br /><a href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</a><br />http://lists.strath.ac.uk/mailman/listinfo/esp-r</blockquote></div><br /><div> <span style="border-collapse: separate; color: #000000; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px" class="Apple-style-span"><div style="word-wrap: break-word"><div><a href="mailto:achim.geissler@intergga.ch">achim.geissler@intergga.ch</a></div><div><br /></div><div><br /></div></div></span><br /> </div><br /></div><br /> <br /> <hr /> <br /> _______________________________________________<br /> esp-r mailing list<br /> <a href="mailto:esp-r@lists.strath.ac.uk" class="autolink">esp-r@lists.strath.ac.uk</a><br /> <a href="http://lists.strath.ac.uk/mailman/listinfo/esp-r" target="_blank" class="autolink">http://lists.strath.ac.uk/mailman/listinfo/esp-r</a></BODY></HTML>