<html> <head> <style> .hmmessage P { margin:0px; padding:0px } body.hmmessage { font-size: 10pt; font-family:Verdana } </style> </head> <body class='hmmessage'> Thanks, Jon and Monika.  Does the "known: boundary" type of node not count as a boundary node?  I specified its ambient temerpature and pressure as 20C and 0 Pa, repsectively.  Both unknown [zonal] nodes have connections to this node. Liam > From: jon@esru.strath.ac.uk > To: obrien_liam@hotmail.com; esp-r@lists.strath.ac.uk > Date: Fri, 10 Jul 2009 08:14:27 +0100 > Subject: [esp-r] Re: Problem with airflow network > > > It is essential that there be at least one connection to a boundary node. The > solver really needs this rule to be followed. > > For more information on defining air flow networks there is a chapter in the > current version of the ESP-r Cookbook (ESRU web page -> software downloads -> esp-r > -> beginners guide > > -Jon Hand > ________________________________________ > From: esp-r-bounces@lists.strath.ac.uk [esp-r-bounces@lists.strath.ac.uk] On Behalf Of Liam O'Brien [obrien_liam@hotmail.com] > Sent: 09 July 2009 20:24 > To: esp-r@lists.strath.ac.uk > Subject: [esp-r] Problem with airflow network > > Hello everyone, > > I'm setting up a fairly rudimentary airflow network, in which two zone air nodes exchange air with a third node that is intended to mix the air and send it back to the nodes. A fixed volume rate component moves the air. The "mixing" node was assigned to known boundary conditions of P=0 Pa, T=20C. However, after several tries, I continue to get the following message for each timestep: > > Please check (in the following order) that: > - each node has some flow path to a boundary pressure and > - iteration convergence control is not too strict. > Day 2 Month 1 Hour 24.000: 100 iterations; flows solution failed > > I assume the first issue is triggering the message. I would have thought that having the mixing node at known conditions would alleviate this error. > > Any thoughts? (I realize this could be accomplished in the operations file, but I want something more sophisticated eventually.) > > The afn file is below. > > Thanks very much! > > Liam O'Brien > > ---------------- > > 3 1 4 1.000 (nodes, components, connections, wind reduction) > Node Fld. Type Height Temperature Data_1 Data_2 > south 1 0 2.5000 20.000 0.0000 250.01 > north 1 0 2.5000 20.000 0.0000 250.01 > Mixing 1 2 20.000 0.0000 0.0000 2.0000 > Component Type C+ L+ Description > Circulation 30 2 0 Constant vol. flow rate component m = rho.a > 1. 0.200000003 > +Node dHght -Node dHght via Component > south 8.750 Mixing -8.750 Circulation > north 8.750 Mixing -8.750 Circulation > Mixing -8.750 south 8.750 Circulation > Mixing -8.750 north 8.750 Circulation > > ________________________________ > Windows Live helps you keep up with all your friends, in one place.<http://go.microsoft.com/?linkid=9660824> > > _______________________________________________ > esp-r mailing list > esp-r@lists.strath.ac.uk > http://lists.strath.ac.uk/mailman/listinfo/esp-r <hr />Windows Live helps you keep up with all your friends, <a href='http://go.microsoft.com/?linkid=9660824' target='_new'>in one place.</a></body> </html>