Layer to get smoke height and temperature

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ruben....@gmail.com

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Mar 9, 2021, 10:32:28 AM3/9/21
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Dear Colleagues,

I am running a simulation and trying to get information about smoke height & temperature, using Pyrosim 2020.
The problem I found is this. I set the layer between 0.05 m and 2.40 mts ( just an example) and as a result I get a temperature graphic starting on -20ºc to let say 80ºc-
if I have a room of 3 mts height and the cellss are 0.25 x 0.25 mts; I used to set the layer between 0 to 2.98 mts, but that gives me a graphic of temperature very erratic starting on negative temparetures.
Any idea about how to set the layer?
Thanks

Ruben

fde

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Mar 9, 2021, 11:17:32 AM3/9/21
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Have you searched "layer height" in this discussion forum? You might find a handful of topics which might help you.

dr_jfloyd

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Mar 9, 2021, 12:49:31 PM3/9/21
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You should look at the actual .fds file being written by Pyrosim and make sure that Pyrosim has properly written your device input.

Layer height and temperature are computed following the process outlined in the FDS User's Guide. That process is based on the assumption that a stratified layer exists at the location where you are trying to measure the layer height. If that is not the case (for example, trying to measure layer height inside the fire or in a location where no layer develops), then the method's output will not be meaningful.

Dr.Akilan Raja

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Mar 10, 2021, 3:57:19 AM3/10/21
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Using Layer height command is there any way to find the flame height with respect to time for entire combustion process?

dr_jfloyd

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Mar 10, 2021, 6:53:53 AM3/10/21
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No.

Dr.Akilan Raja

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Mar 10, 2021, 10:49:36 AM3/10/21
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Ok thanks, so the conclusion is not possible to measure the flame height with respect to time for entire combustion process using FDS right?

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Randy McDermott

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Mar 10, 2021, 10:55:09 AM3/10/21
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What do you mean by "entire combustion process".  Of course you can determine the flame height.  Read the validation guide on flame height.

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Dr.Akilan Raja

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Mar 10, 2021, 11:02:24 AM3/10/21
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From ignition to quenching of flame height data for every seconds. For example my burning time is 450 sec means, is it possible to pull the 450 flame height data from the scenario? Moreover I already read the flame height validation details in technical guide from that I couldn’t able figure it out how to get flame height data per second?

Randy McDermott

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Mar 10, 2021, 11:04:55 AM3/10/21
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You will have to average the HRR in planes of constant z (height) and then write a script to to determine the cumulative HRR and compare it with the total.  This is what we do.  See

fds/Utilities/Matlab/scripts/flame_height.m

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Dr.Akilan Raja

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Mar 10, 2021, 11:29:55 AM3/10/21
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Either hrrpul or hrrpuv which one is best to predict the exact flame height? Please share if you have any related solved file for flame height calculation?

dr_jfloyd

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Mar 10, 2021, 11:32:59 AM3/10/21
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See the validation guide for flame height. All the validation guide input files are available on github: https://github.com/firemodels/fds/

Dr.Akilan Raja

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Mar 10, 2021, 11:45:41 AM3/10/21
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Thank you so much Randy. Now I have hope to measure flame height with respect to various time intervals after seeing your codes.

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