Impossibility to watch the SOOT DENSITY in Smokeview

[Aubert Jean-Baptiste]

Hello everyone,

I am working for a few weeks with FDS to model fire in tunnels. But I can’t display the SOOT DENSITY in 3D SMOKE in Smokeview anymore (for a few days). I do not understand why. I have done my research on this group trying some tricks :

-          Compress my files with ZLIB. However, I think this is not a problem of size of the 3sd files because I have some other simulations whose 3sd files are bigger, and for which the SOOT DENSITY is visible in Smokeview.

-          Playing on “Data Loading” in the Time Tab, in Smokeview, but no effect has been observed.

Does anybody have an idea to display the SOOT DENSITY in my case ?

Please find attached the message as regards the loading of soot (what I want to see) and hrrpuv (that I can strangely load and see on the other hand).

Thank you.

[dr_jfloyd]

Did you specify a SOOT_YIELD on the REAC line?

[Aubert Jean-Baptiste]

Hello dr_jfloyd,

Thanks for your answer.

In fact, in all my cases the REAC line is defined without the parameter SOOT_YIELD. And yet, in some of these models, I can watch the SOOT DENSITY, and it is not the case in others.

My REAC line, the same in all files, is attached.

Your answer leads me to wonder : how could I know in advance the fraction of fuel mass converted into smoke particulate (SOOT_YIELD) ? And same question for the fraction of fuel mass converted into CO (aka CO_YIELD) ?

I mean, is the SOOT_YIELD/the smoke rate not a result of a particular fire, much more than a parameter to define before computing ?

I hope I am enough understable, sorry for the language (French).

Thank you a lot!

[Kevin McGrattan]

There is no SOOT_YIELD on your REAC line. 

[dr_jfloyd]

Per the FDS User's Guide tables of input parameters, the default SOOT_YIELD is zero. If you do not specify SOOT_YIELD, your fire will produce no soot, and there will be no soot data in the s3d data files for Smokeview to display.

It is up to you as the FDS user to determine an appropriate soot yield for your specific fuel and fire scenario. Possible resources to help you are the SFPE Handbook, publicly available reports from the various fire research organizations, proceedings of the IAFSS Symposia, and journals (Fire Tech, Fire Safety Journal, Combustion and Flame, Journal of Fire Science, etc.)

[Ahmad Orabi]

Hello everyone,

I am using FDS to analyze the smoke behaviour in industrial hall 45m x 15m x 8m in an area has wind speed is 3 m/s. The problem I have two wind profile options, the Monin Obukhov and the custom wind profile.
The Custom wind profile provides a velocity stable with height neglecting the wind speed change with height which is critical in my project. With MO wind profile I see a wind movement inside the building even though it is totally closed with no windows or doors, this wind has negative speed, and it affects the fire shape and smoke layer.
I need an explanation for that since I didn’t understand the reason, and a solution if existed. this pic shows the wind profile with Monin-Obukhov

Thanks in advance.

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[Kevin McGrattan]

Try the latest version of FDS and then report back.

[Aubert Jean-Baptiste]

Indeed, with a SOOT_YIELD which is defined, it works better and I can visualize the smoke... Thanks a lot for your answers Kevin and dr_jfloyd !