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

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Tim
Posts: 1565
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: 22
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 8 times
Capture.PNG

Tim
Posts: 1565
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: 22
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: 1565
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: 22
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: 1565
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

Thea
Posts: 4
Joined: Wed Jul 15, 2020 10:01 am

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

Postby Thea » Wed Jul 29, 2020 10:57 am

Tim wrote:Hi Sara,

Yes, your model area looks fine. Could be caused by the meteorological conditions as well.

Best regards,
Tim


Hi Tim,

I tried to run a 3-day simulation with full forcing. I got the same problem here and the Logfile showed there was a 'flow problem'. So I added 5 more grids on the Z level and made sure that there was enough buffer area. But the 'flow problem' showed up again during the second time. I don't know what to do next. Could please take a look at my SPACES and FOX files?
BTY, I didn't use the single wall either.
Thanks a lot!

Best regard,
Thea
Attachments
simulation072020.zip
Spaces and fox
(249.58 KiB) Downloaded 8 times

Tim
Posts: 1565
Joined: Mon May 15, 2017 3:46 pm

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

Postby Tim » Thu Jul 30, 2020 8:31 am

Hi,

You have some large trees in there and your model top is at 40 m. You will have to add much more Z cells and/or add telescoping and/or increase z resolution. I would try to reach 100 m absolute height for your model area.

Best regards,
Tim

nathphil
Posts: 22
Joined: Wed Oct 02, 2019 7:58 am

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

Postby nathphil » Mon Aug 10, 2020 10:50 am

Hi ENVI-Met team,

I come back to you on this topic concerning a new simulation I'm trying to run.

I've already run this simulation four times, hence I suppose that it couldn't be a random error. Whenever the sim file is initiated, it crashes after approximately four hours of simulation. The involved grids (337,5; 336,5; 338,2; 337,4; 336,2) are all located in the empty cells at border that I've added in order to avoid stability and turbulence issues (I've checked this side with the Model inspector tool).

There is no building or vegetation on these empty cells, just the "loamy soil ". In the model initialisation there wasn't any apparent issue. I've checked the PANIC DUMP files : they indicate that the air temperature, the relative humidity and the CO2 became very problematic in the involved grids.

There is undoubtedly something I've forgotten, however I must admit that I don't know what. Perhaps you could clarify that for me...

I'm sorry for the inconvenience, and hope I've posted in the good topic...


Just in case here is the involved area : https://we.tl/t-LVeazPLOpp

Thank you very much in advance for your reply.

Best regards,

Nathalia
Attachments
SimuPresquile2.PNG
SimuPresquile1.PNG
SimuPresquile.PNG

Tim
Posts: 1565
Joined: Mon May 15, 2017 3:46 pm

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

Postby Tim » Mon Aug 10, 2020 11:57 am

Hi Nathalia,

You are right, there is absolutely nothing specific about those cells in the model area. Maybe there is something wrong with the general simulation settings? Soil too dry or wind speed/direction change too fast?

Best regards,
Tim

nathphil
Posts: 22
Joined: Wed Oct 02, 2019 7:58 am

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

Postby nathphil » Mon Aug 10, 2020 12:26 pm

Hi Tim,

Thank you for your prompt reply.

I'm already relieved to see that the issue doesn't seem to come from the geometry of the area itself.

Concerning the general simulation settings, I'm already using exactly the same parameters (same forcing file and same soil conditions) for another simulation which (for the moment !) seems to work without any problem (it concerns another area that is not far of this one).

I must admit that sometimes, the wind speeds might be low. However, four another simulations had worked without any issue under these forcing conditions. These values comes from one of our meteorological stations.

Here are just in case the forcing and the simx files : https://we.tl/t-tIZ5N8xyWD

If you don't find any strange value in these files, do you think that it would change something if I remove the involved empty grids (I would in this case remove all the south empty grids) in order to add them again after ? (This appears like a dumb suggestion, but I'm a little desperate...)

Thank you very much again for your reply.

Best regards,

Nathalia

Tim
Posts: 1565
Joined: Mon May 15, 2017 3:46 pm

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

Postby Tim » Mon Aug 10, 2020 2:20 pm

Hi Nathalia,

The simulation files also look OK to me. I only think that the soil temperature is pretty high with 32 °C, especially for the deeper layers. However, I am not sure if the issue might be connected to that. I can only advice you to try different things in order to erase them as possible reasons: Change soil temperatures, simple forcing instead of full forcing, deleting those empty cells etc. You may find the reason then.

Best regards,
Tim

yangshaoqi
Posts: 1
Joined: Wed Aug 12, 2020 3:51 am

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

Postby yangshaoqi » Wed Aug 12, 2020 6:40 am

Hi Tim,

I tried to run a 24 hours simulation with full forcing. I got the same problem here and the Logfile showed there was a 'flow problem'. It seems the Z cells is Ok. Could please take a look at my SPACES file?

Wish you have a nice day, Thanks a lot!

Best regards,
Yang
Attachments
ZhiGao2020630.zip
(1.07 MiB) Downloaded 3 times

Tim
Posts: 1565
Joined: Mon May 15, 2017 3:46 pm

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

Postby Tim » Wed Aug 12, 2020 7:04 am

Hi Yang,

You have a different issue there. Wind speed in FullForcing is much too low, e.g. 0.1 m/s for 7:00 and 8:00. That will not work.

Best regards,
Tim


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