[esp-r] Re: Problem with airflow network

[Jon Hand]

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 at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] On Behalf Of Liam O'Brien [obrien_liam at hotmail.com]
Sent: 09 July 2009 20:24
To: esp-r at 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>