Hello Aizaz, I think the problem is not the node heights in my case, however I'm not sure. The .afn file is attached. Regards, Mostapha Sadeghipour <div class="gmail_quote">On Wed, Jun 9, 2010 at 3:54 PM, Aizaz Samuel <<a href="mailto:aizaz.a.samuel@strath.ac.uk">aizaz.a.samuel@strath.ac.uk</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Look up how node heights are defined in exemplars>network ventilation>alternative facade vent..... Theory can be found in Jan Hensen's thesis (section 4.3.2) available at <a href="http://www.esru.strath.ac.uk/publications.htm" target="_blank">http://www.esru.strath.ac.uk/publications.htm</a> -- Dr Aizaz A Samuel Department of Mechanical Engineering University of Strathclyde M324 James Weir Building 75 Montrose Street Glasgow, UK G1 1XJ T:+44 141 548 5765 F:+44 141 552 5105 <div><div></div><div class="h5"> On Wednesday 09 June 2010 11:28, Mostapha Sadeghipour wrote: > Dear esp-r users, > > I'm modeling an atrium with a closed glass roof. The atrium has nearly 16m > height and it only connects to the outside through 3 cracks on the roof. I > divided the atrium into 5 vertical zones, and adjacent vertical bypass > zones. They are connected to each other through fictitious faces. > > Common orifice components connect zone nodes to each other vertically, and > door component connects zone nodes to bypass nodes horizontally. The > attached image shows the Air Flow Network in my model more clearly. > > I supposed that esp-r includes the stack effect whenever delta height > between the nodes and the component is not zero. So I expected to have a > stack pressure in the vertical connections. But when I check the results > the stack pressure in the connections are zero! > > I'm also curious how esp-r consider the stack effects and the gravity? The > components dP are set manually and there is no "g" in the equations? Where > I can find the PSTACK equations that is used to calculate DP: > DP=PRES(IDPS)-PRES(IDNE)+PSTACK(ICNN). > > Thanks in advance. > > Mostapha Sadeghipour </div></div></blockquote></div>