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Old   March 4, 2014, 12:36
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Quote:
Originally Posted by vishal_s View Post
Hi all,
What is the function of 'reltol'....? Can it be help in any way for improvement of the solution??

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Vishal
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Old   March 5, 2014, 01:33
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Hi Tobi,
I also simulte this swilr flame using kOmegaSST model and I plot the residual as follows..
https://www.dropbox.com/s/sqf5vuq4gg...idual_plot.pdf
Why there is lots of fluctuation in P equation..?
Can make some comment on this p equation??

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Vishal
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Old   March 5, 2014, 05:44
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Hey vishal,

hmmm ... how do you plot this graphics?
Normally the residuals are from 1 to -1e-6 or sth. like that.

Strange residuals!

For the pressure equations ... I have to make a Research for that
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Old   March 5, 2014, 06:25
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Hi Tobi,
Actually I plot it in excel.. not accustomed in gnu plot....
Another thing regarding H calculation...for different fuel...I have no idea regarding this calculation of H??

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Vishal
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Old   March 5, 2014, 07:26
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Quote:
Originally Posted by vishal_s View Post
Hi Tobi,
Actually I plot it in excel.. not accustomed in gnu plot....
Another thing regarding H calculation...for different fuel...I have no idea regarding this calculation of H??

Regards,
Vishal

Hi,

you can use pyFoam for plotting residuals (search in the Forum or openfoamwiki).

For the equation of H.
This is an ordinary conserved Transport equation if the Radiation model is off. Elsewise it is an ordinary tranpsort equation like Z with an additional source term (Radiation).


If the Radiation is off, the Quality results of mixture fraction and "enthalpy" is similar/equal. Only the values are different.

Therefor you can Derivate that this is only a Transport equation which gives the "mixture" of the adiabatic enthalpy of oxidizer and fuel.

Using this mixtured "enthalpy" you can calculate the deflection to the adiabatic enthalpy of the flame if Radiation is on.

a) if you have no Radiation activated this should be Zero. Due to numerical Errors you will get a very very small deflection but it can be neglected. Strange results can be calculated with wrong schemes too!

b) if you have Radiation on, then you can calculate the deflection to the adiabatic flame and that is called enthalpy defect. With this value you interpolate between different PDF´s and therefor it is possible to calculate non-adiabatic flames.

Now you see, that this is not a normal enthalpy equation like you have in other solvers.


Hope my formulation is clear and you understand how this works (:


Regards
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Old   March 7, 2014, 06:02
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Quote:
Originally Posted by vishal_s View Post
with kinetic mechanism GriMech 3.0
Hi Vishal,

I see that you are using GriMech 3.0, can you (or anybody else) share the required "idealgas" and "reactions" files needed for flamelet generation, since I only have them for the Polimi reaction mechanisms. I know that it is also possible to build them yourself, however, I am not that experienced with Cantera at the moment.

Tobi, has Alberto mentioned any time frame in which the new libOpenSmoke tool will be released (e.g. within one month or one year).

Regards,
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Old   March 7, 2014, 06:12
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Would this help you in any way?

http://www.me.berkeley.edu/gri-mech/...30/text30.html
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Old   March 7, 2014, 06:16
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Unfortunately not, since these files are in different format than the onces directly required for libOpenSmoke
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Old   March 7, 2014, 06:19
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They are both available in Chemkin format if I am not mistaken?
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Old   March 7, 2014, 06:21
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Ok, so which file should I use then as idealgas and which as reactions in de libOpenSmoke utility?
The files of for example PolimiC1C3 are in binary format, so unfortunately cannot open them to compare this file format with GRI.
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Old   March 7, 2014, 06:37
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Not sure about the files you are talking about, but I have available:

in libOpenSMOKE/utilities/kinetics/CHEMKIN:

PolimiC1C3HT_1006/PolimiC1C3HT_1006.kin
PolimiC1C3HT_1006/termo_1006.tdc
PolimiC1C3HT_1006/tran_1006.tra

and they have similar contents/format as
grimech30.dat
thermo30.dat
transport.dat

which I found from the abovementioned website.

None of them are binary. I used those to generate the flamelets with the utilities that were provided by the libOpenSMOKE team.

There may have been one or two corrections/replacements I had to make, but I do not remember exactly what I did almost 2 years ago.

Regards,
Tom
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Old   March 7, 2014, 06:39
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Quote:
Originally Posted by TBO View Post
Ok, so which file should I use then as idealgas and which as reactions in de libOpenSmoke utility?
The files of for example PolimiC1C3 are in binary format, so unfortunately cannot open them to compare this file format with GRI.
There is a pre-processing tool that create the Binaries you need. The input file is gri 3.0. additionally you need to transport final and the thermodynamic file.

They are available at the crack homepage or in the first reconstructed Lib open smoke Toolbox that was made by Bruno - I mean the rebuilt of the toolbox..


the team does not mention a time when the new updates will be available for other users that's the problem because 2 years ago they mentioned that the lip open smoke tool will be upated soon but there was never a release and so its still nothing happens.


Regards.

Ps: I am analyzing the flamelet generator of libopensmoke
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Old   March 7, 2014, 15:59
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Quote:
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the team does not mention a time when the new updates will be available for other users that's the problem because 2 years ago they mentioned that the lip open smoke tool will be upated soon but there was never a release and so its still nothing happens.
I think the closest they provided as an update to libOpenSMOKE was laminarSMOKE and CatalyticFOAM:
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Old   March 7, 2014, 16:38
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Originally Posted by wyldckat View Post
I think the closest they provided as an update to libOpenSMOKE was laminarSMOKE and CatalyticFOAM:
No ... A few posts befor I told other things.
I wrote with Alberto last week
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Old   March 8, 2014, 04:08
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Hi all,

just one question to you.

With the NASA polynomials it is possible to calculate the heat capacity, entropy and enthalpy of the species X on different temperatures.

We can do the same for the transport properties but where can I find the polynomials for the calculation?

At the moment I am analysing the flamelet-creator tool from Alberto Cuoci et. al. but the polynomials which are given in the output files are still modified so that it is not possible to figure out what pre-factors are in the eqn.

I will try to search again today evening but maybe someone of you knows the answer/link/literature ...
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Old   March 19, 2014, 04:58
Default Fluctuation in Zvar in swirl flame
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Greeting all,
I simulate the SM1 sydney swirl flame using all modification as suggested by tobi and variance equation off mode. But there is lot of fluctuation in Zvar .
https://www.dropbox.com/s/qc85it4m42jgzmd/Zvar.pdf

Can you suggest something regarding this issue ??

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Old   March 24, 2014, 07:29
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Greeting all ,
I was trying to simulate bluff body flame (sandia HM1) from last few days using the flameletSimpleFoam solver.But there is some issues . i am attaching some of the contour plots of velocity and temperature after Time= 40000 .


Plz somebody suggest me whats wrong in my case , if needed i can send my case files ,

Thanks ,
Regards ,
Sonu
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Old   March 24, 2014, 07:49
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Hi,

I know that Alberto et. al. do this simulation with very accurate solution.
Please try to use the "not modified" and "original" code of the libOpenSMOKE tool and let us know if you will get better results.

The official tool is available for 1.7.x and 2.0.x at Brunos github.
Maybe I made a mistake in converting it to 2.2.x - i just made the validation with COH2N2 flame.


Regards Tobi
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Old   March 25, 2014, 01:31
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Greetings all

@ Sonu

The simpleFoam solver does not have any problems (If you look at this thread pages, you will see that different bluff-body stabilized flames are simulated with this solver).

You must have a problem with your PDF tables or schemes (unstable ones).

Try using schemes proposed by Tobi or in case of using Alberto's original code, his schemes, you will get reasonable results.

Bobi
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Old   March 25, 2014, 02:43
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Greeting bobi ,

i wll check both things PDF table and the schemes and then let you know ..

Thanks for suggesting


Regards ,
sonu
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