the temperature,the humidity or the co2 field has become unstable

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Tim
Posts: 1373
Joined: Mon May 15, 2017 3:46 pm

Re: the temperature,the humidity or the co2 field has become unstable

Postby Tim » Mon Jan 13, 2020 9:04 am

Hi Sara,

That is an internal message: ENVI-met tries to avoid an error by resetting the temperature field of the wall surface which got corrupted during the simulation. This issue can have multiple reasons. Since the model area looks fine, I would still recommend to reduce wind speed from 14 m/s to something stable (lower than 4 m/s) to be sure that this cannot be the reason for your issues.

Best regards,
Tim

nathphil
Posts: 19
Joined: Wed Oct 02, 2019 7:58 am

Re: the temperature,the humidity or the co2 field has become unstable

Postby nathphil » Wed Apr 01, 2020 7:39 am

Hi ENVI-Met team,

I'm writing on this old topic because my issue seems to be the same as the original request.

The message "the temperature, the humidity or the Co2 are become unstable" error also appeared on my computer. The issue concerns the grid 283,451,6. I was looking for any single wall which could explain the unstability, but I didn't find it yet (may be I missed something in the PANIC DUMP files...).

Here are my area and the screenshot of the issue message.

It must be the thousandth message dealing with this kind of subject... I'm sorry for the inconvenience.

Thank you in advance for your reply, hope you're well.

Best regards,

Nathalia
Attachments
Krutenau.zip
(5.12 MiB) Downloaded 4 times
Capture.PNG

Tim
Posts: 1373
Joined: Mon May 15, 2017 3:46 pm

Re: the temperature,the humidity or the co2 field has become unstable

Postby Tim » Wed Apr 01, 2020 9:23 am

Hi Nathalia,

It can have multiple issues, not only connected to SingleWalls or ghost cells. However, we also recognized that this error occurs randomly sometimes. So, if it was a random error without reason, it may not occur if you simply restart the simulation.
We are currently in the hunt for the reason of such random instabilities and more or less finally found the parallelized section where it happens.

Best regards,
Tim

nathphil
Posts: 19
Joined: Wed Oct 02, 2019 7:58 am

Re: the temperature,the humidity or the co2 field has become unstable

Postby nathphil » Wed Apr 01, 2020 9:34 am

Hi Tim,

Thank you very much for your reply.

I've actually noticed in a previous simulation (for another area) that this error can occur randomly and then disappear with a second/third simulation. Unfortunately, I've already restart this simulation, and this issue is still here for the same grid. Could it be possible that the temperature/relative humidity/CO2 becomes unstable in the concerned grid because this one is surrounded by too many buildings of different heights ?

Best regards,

Nathalia

Tim
Posts: 1373
Joined: Mon May 15, 2017 3:46 pm

Re: the temperature,the humidity or the co2 field has become unstable

Postby Tim » Wed Apr 01, 2020 2:51 pm

Hi Nathalia,

Okay hm, that is strange. No, the buildings around the cell should not be a problem in general. However, according to your screenshot there are pretty low wind speeds incoming. Within such a courtyard with high buildings around, the wind speed might be very very low and could lead somehow to such instabilities. So, the only suggestion I might have would be to increase the wind speed.

Best regards,
Tim

nathphil
Posts: 19
Joined: Wed Oct 02, 2019 7:58 am

Re: the temperature,the humidity or the co2 field has become unstable

Postby nathphil » Sun Apr 05, 2020 9:11 pm

Hi Tim,

Thank you very much for your prompt reply.

I'll try to resolve this issue by following your tips. With this forcing file which contains these low wind speeds I've already run a simulation without issue. However, it was in another model area, with much less buildings than this one.

Just another question : I've run two other simulations for two other areas. They're still runing, but I guess that they will stop at a given time because of the recurrent warning "Maximum divergence in flow field" I've noticed something strange : the concerned grid is always the grid that is located just next to the limit of the area (for example here : the first zone is 342 x 752 x 35 m and the grid with the flow field issue is the 342, 752, 39. For the second zone of 713 x 400 x 65 m, the problematic grid is the 713, 400, 69). However I've tried to follow the advices of "Model inspector" tool and add many horizontal and vertical empty grids (until the text becomes green). Is there an explanation I've missed ?

Thank you very much in advance for your reply.

Best regards,

Nathalia
Attachments
Starlette.PNG
Malraux.PNG

Tim
Posts: 1373
Joined: Mon May 15, 2017 3:46 pm

Re: the temperature,the humidity or the co2 field has become unstable

Postby Tim » Mon Apr 06, 2020 7:35 am

Hi Nathalia,

No, they are found in every simulation giving information where maximum divergence is found and is no problem at all.
What is a bit concerncing, is that Turbulence Updating in the initialisation phase was unstable at a specific grid cell in the lower picture. You may check that cell for something that could cause turbulence.

Best regards,
Tim


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