‘WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3

[mcgratta]

‘WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3
Time Step: 4023, Simulation Time: 28.03 s

ERROR: Numerical Instability - FDS stopped (CHID: 40kw_zx_t35_small)
[runfds.exe] subprocess exit: 0
’Hello teacher, I had this problem during the FDS simulation, which caused the simulation to stop early, I would like to ask what is the reason。I saw this result after looking at the out file. Thank you, thank you
40kw_zx_t35_small.txt

Originally posted by @Suo-CY in #14898 (comment)

[mcgratta]

I am running the case now with the latest FDS source code. You might want to try using the latest nightly build.

[Suo-CY]

Dear Kevin McGrattan, Thank you very much for your previous response. I have adjusted the obstacle coordinates in my model accordingly, and the simulation is currently running smoothly. I would also like to take this opportunity to inquire about some additional experimental details that are crucial for my ongoing research. Recently, I have been using the HRR (Heat Release Rate) datasets provided by NIST to train a machine learning model aimed at predicting fire behavior based on visual data. For the accuracy and reliability of my model, knowing the camera focal length and the distance between the camera and the burning objects during the experiments is essential. However, I have not been able to locate this information in the available documentation(Fire Calorimetry Database). Would it be possible for you to kindly share the relevant camera specifications and setup parameters used during the experiments? This information would greatly enhance the quality and interpretability of my research. I truly appreciate your time and support. Wishing you continued success and all the best in your work. Warm regards, Suo

…

---- Replied Message ---- | From | Kevin ***@***.***> | | Date | 07/31/2025 21:15 | | To | ***@***.***> | | Cc | ***@***.***>***@***.***> | | Subject | Re: [firemodels/fds] ‘WARNING: Minimum density, 0.115 kg/m3, clipped in Mesh 3 (Issue #14910) | mcgratta left a comment (firemodels/fds#14910) I am running the case now with the latest FDS source code. You might want to try using the latest nightly build. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you were mentioned.Message ID: ***@***.***>

[drjfloyd]

You would need to look at the individual test reports for each test series to see if the camera data was recorded. It may not have been.

[mcgratta]

Unless the information is in the test report, it was not recorded.

[Suo-CY]

In addition to the camera specifications, I am particularly interested in the distance between the camera and the burning objects during the experiments. For example, on this page:
https://www.nist.gov/el/fcd/vertical-upward-flamespread-parallel-panels,
I could not find detailed information about the camera placement or its distance from the test setup.

Would it be possible to know the typical camera distance used in these experiments? Additionally, could you kindly point me to any official test reports or documentation where these experimental parameters are described?

Thank you again for your time and help.

[mcgratta]

The link to the test report is on the page that you cite.

[Suo-CY]

Thank you for guiding me to the right documentation. That was exactly what I needed!