[esp-r] Re: simulation message - non-convergence of air flow networks

[Arianna Sdei]

Hi Achim,

thank you for that! How can I do convergence checking? Is there any way ESP-r can automatically check if there is a problem with the airflow network? I have tried with smaller time steps but no change. Let me know,

Regards,
Arianna

From: esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Achim Geissler
Sent: 27 October 2013 16:47
To: Aizaz Samuel
Cc: esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: simulation message - non-convergence of air flow networks

Dear Arianna,

in addition to the below, it sometimes helps to reduce simulation time steps (increase number of steps per hour). Also, you can change the parameters used for convergence checking (either every run manually or in the code and recompile).

Best
Achim



On Oct 22, 2013, at 9:04 AM, Aizaz Samuel <aizaz.a.samuel at strath.ac.uk<mailto:aizaz.a.samuel at strath.ac.uk>> wrote:


Arianna,

Somewhere in your model there is mass imbalance that is more than the tolerance allowed within the solver. Usually happens if you close a flow path using control (e.g. window closes but air is still being blown into the room from a fan). I would recommend to check this by removing control and then running the model. Another way forward is to make a sketch of the flow network and visually check if a bad flow path occurs given the constraints of the control you are trying to impose. A usual solution is to always have a flow path from internal nodes to external ones via small cracks (which is correct for most situations).

Another (rarer) reason is that you may have two components in series that have hugely different flow resistances.

Regards,
Aizaz

On 22/10/13 12:22, Arianna Sdei wrote:
Dear All,

I am simulating using an air flow network and while running the simulation I get the following message:

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

Can someone help me to interpret what that means and what should I look at in the model? Thank you,

Arianna

Arianna Sdei

Research Fellow IFORE (Innovation For Renewal)

UNIVERSITY OF BRIGHTON

Moulsecoomb, Lewes Road, Brighton, BN2 4AT

direct line: 0044 (0)2036747268

mobile: 0044 (0)7981739024



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