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Fire Dynamics Simulator
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Radiative heat flux distribution trend different for different diameter #883

Closed gforney closed 9 years ago

gforney commented 9 years ago 
Please complete the following lines...

Application Version: V5.4
SVN Revision Number:
Compile Date:15/09/2009
Operating System:XP sp2

The 30 cm and 50cm dimeter pool fire is simulated. Fuel is gasoline. For 30
cm the radiative heat flux trend matches with the experimental measurements.

For 50 cm pool radiative heat flux distribution trend doent match with
experimental measurements.(graph attached for your reference)

This problem was observed with diesel too in past.

kindly let me know how to justify this variability? how to fix this problem .
Is it appropriate to conclude that FDS doesnt work well for the blended
fuels like gasoline,diesel. etc.?

Regards....
Saumil

Original issue reported on code.google.com by saumil2525 on 2009-10-22 06:59:03

gforney commented 9 years ago 
Saumil,

I have been trying to reproduce your results.  So far I am getting close.  I have a
3cm case that ran and gives me a peak HRRPUA of 22 kW/m2 at Z/D of 1.5.

But it is not clear to me where you are getting your data.  You previously posted an
ascii file (gas3.0.dat).  This file is not clear to me.  I cannot at all tell from
this set of data why you would put your radiometers at x=0.7 m, for instance.

So, I request two things: (1) convince me that your radiometers (DEVCs) in the input
file are at the same place as where the data was taken for the 70 cm pool, and (2)
provide me with a simple, comma delimited file with one column for z/D and one column
for q (kW/m2).

Thank you.
Randy

Original issue reported on code.google.com by randy.mcdermott on 2010-03-09 20:58:47

gforney commented 9 years ago 
I also found an instability with 1.6 cm resolution.  It it located on the pool base.
 Will hopefully be able to narrow it down from there.

Original issue reported on code.google.com by randy.mcdermott on 2010-03-09 22:13:24

gforney commented 9 years ago 
Dear sir

sorry for the delay as I was out of campus for 4 days. 

1.) Pls find the puffing frequency sample calculation sheet.In simulation
pressure,temperature and w velocity measuring devices are kept at H/D = 1

2.) Currently paper on the 'Emmisivity measurement and heat flux validation using
thermal camera is under review with journal. hence not in position to forward you the
same but i will send you the writeup latest by day after tomorrow.

3.) The very first radiaometer is placed at height of 0.2 and at 0.7 m from the
location which is identical to our measurement.(will send you writeup soon)

4)find here with the latest cvs file.

Regards..
Saumil

Original issue reported on code.google.com by saumil2525 on 2010-03-17 04:28:22

gforney commented 9 years ago 
Saumil,

Thanks.  But this is the same puffing frequency file you showed before.  It does not
tell me how you actually obtained the number 2.2 Hz, for example.  I very much doubt
that the lowest mode for W and T are different in the FDS results.

Thank you for the csv file of the radiation intensity.  This is much simpler than the
previous data file.  Can you tell me what ITR9 and ITR18 represent?

R

Original issue reported on code.google.com by randy.mcdermott on 2010-03-17 12:23:55

gforney commented 9 years ago 
oops! sorry for the inconvinience.
pls find the calculations attached herewith. ITR9 And ITR 18 have different
parameters or versions. This is for our reference only.(refer book1.xlsx).

regards..
Saumil

Original issue reported on code.google.com by saumil2525 on 2010-03-18 02:55:01

gforney commented 9 years ago 
Saumil,

Regarding the puffing frequency, you are not quite computing this correctly.  You are
only looking at the real components of the FFT.  You need to look at the power
spectrum, which entails multiplying the Fourier coefficients by their complex
conjugate -- I showed how to do this in the Matlab script I sent you above.

Second. I still do not understand Book1.xlsx.  What I need is the actual data in a
very simple two column file where one column is the height above the burner and the
other column corresponds to the heat flux intensity at the DEVC locations in the
attached input file.  By the way, this is the input file I would prefer you use.  I
found problems with the original.

R

Original issue reported on code.google.com by randy.mcdermott on 2010-03-18 12:26:05

gforney commented 9 years ago 
Dear sir 
pls find the file in required format which contains the actual heaight and non
dimensional height of the devices.

As you highlighted we are computing the PF considering the real part only but we will
run your script and getback to you.

Original issue reported on code.google.com by saumil2525 on 2010-03-19 05:55:19

gforney commented 9 years ago 
Dear sir
pls send input file (devc_file) for the powespectrum.m

Regards..
Saumil

Original issue reported on code.google.com by saumil2525 on 2010-03-19 11:51:38

gforney commented 9 years ago 
Saumil,

Thanks for the data.  This is what I needed.

As for the power spectrum, you should use your own devc file if you want the results
from your calculation.  If you are not familiar with Matlab, then maybe this is not
helpful.  But you should be able to look up how to compute a power spectrum in any
reference.

R

Original issue reported on code.google.com by randy.mcdermott on 2010-03-19 12:22:54

gforney commented 9 years ago 
Dear sir 
I am famliar with matlab. but in script, values of some variables are not defined.
so
I thought those are being read from the input file. 
anyways I will run the code.

Regards..
Saumil

Original issue reported on code.google.com by saumil2525 on 2010-03-20 01:39:05

gforney commented 9 years ago 
Dear sir 

After taking conjugate of complex number, very less difference in frequency,
calculated from the pressure and temperature predictions, is observed.
Thanks for the help.

pls refer fft.m and result images.

Regards
saumil

Original issue reported on code.google.com by saumil2525 on 2010-03-20 09:12:16

gforney commented 9 years ago 
Dear sir
 we ran Gasoline_70cm_dx3cm.fds. the results are attached here with. I just want to
know wethere num instability (@ smallere grid size ) problem is resolved so that it
can be ran for finer grid. 
FYIP: @3 cm grid, predicted HRR 670 against input HRR = 770.

I am running the case for Dx = 2.4 cm

Regards..
Saumil

Original issue reported on code.google.com by saumil2525 on 2010-03-20 09:49:11

gforney commented 9 years ago 
result

Original issue reported on code.google.com by saumil2525 on 2010-03-20 09:49:40

gforney commented 9 years ago 
Saumil,

Nice work on the puffing frequency.  So, that is one issue solved.

The short answer to your question about the instability is, no, the problem is not
completely solved.  But, Kevin has been looking at flame heights for a large range
of
Q* cases (0.1 to 10^4) and we are narrowing down on C_EDC = 0.1.  There remains a
more subtle issue with HRRPUA_SHEET that I will not go into here.  In short, you
should wait until we get the validation suite run again and Kevin settles on the new
code for HRRPUA_SHEET; and then we will reexamine the stability and heat flux
distribution for the gasoline case.

Best,
Randy

Original issue reported on code.google.com by randy.mcdermott on 2010-03-21 18:50:07

gforney commented 9 years ago 

I am keenly waiting for new devlopment.By the time if I get some results I will share
with you. 

Thankyou for the help.
Regards..
Saumil

Original issue reported on code.google.com by saumil2525 on 2010-03-22 04:51:19

gforney commented 9 years ago 
Dear sir
I have rerun the Gasoline 70 cm pool fire with latest version. SVN 6004.  The results
are attached here with. I Got improved results with latest version compared to SVN
5210. With refined grid (2 cm), variation is not obsrved much. 

regards..
Saumil

Original issue reported on code.google.com by saumil2525 on 2010-05-14 06:00:15

gforney commented 9 years ago 
Saumil,

C_EDC should be 0.1, then results will look better.

Randy

Original issue reported on code.google.com by randy.mcdermott on 2010-05-14 12:20:37

gforney commented 9 years ago 
Saumil,

Where are we with this?

Randy

Original issue reported on code.google.com by randy.mcdermott on 2011-08-26 19:35:30

gforney commented 9 years ago 
Closing. No response from Saumil in over a year.

Original issue reported on code.google.com by randy.mcdermott on 2012-03-21 12:37:37