[TBO]

Originally Posted by sino75

I tried a lot of things like relaxation factors, maxCourant number or changed the schemes, but I had no success. Courant number doesn't seem to have influence at all.

Correct me if I'm wrong, but since your similation is steady state with flameletSimpleFoam, the Courant number won't have any influence. With the Courant number you define indirectly the required time step in transient simulations. Since your similation is steady state, you do not specify the Courant Number. When you specify it, it does nothing.

[Tobi]

@TBO: What you say is correct (SIMPLE algorithm does not use the Co number because no time derivation is solved).

@Sino75: maybe your mesh is going to get to fine and you resolve turbulence which can not be handled with SIMPLE algorithm. Therefore it could be a good choice to check it with a transient solver.

[sino75]

Thanks for your fast support.
I'm working with flameletSimpleFoam in my master thesis. FlameletPisoFoam is not available in the new version. So I know I would get much better results with PISO or PIMPLE, but I have to use SIMPLE
Are there any possibilities to improve the SIMPLE solver?
Do you know why flameletPisoFoam is not available anymore in the newest version?
Thanks a lot.

[Tobi]

Yes I know why its not available. The reason is that I build that stuff (during and after my masterthesis). In 2.3.x I removed the solver because it is not well tested and at there is also the flamelet solver availible build by Hagen Müller (its using PIMPLE and is for RANS + LES).

At the moment I am building a new lib which can be used for laminar and turbulent flames (RANS + LES) but due to the fact that I am doing it in my spare time, it could take month if its finished.

So you have more possibilities:

• Building the transient solver yourself
• Using Hagens solver
• Using model 2.2.x or 2.1.x
• Waiting (maybe for a long time) till I finished this solver

You can prove SIMPLE also, but what you want to prove if you solve instationarity and you are not solving time derivation?

[sino75]

Hi Tobi,

I'm comparing Hagens solver with this one. So I will use the older version for Piso. If I have enough time, I will try to include Piso (Pimple?!) into new version.
I'm really looking forward to the implementation of LES. So I wish you success.
Thanks again!

[Tobi]

I dont know how it was in previous OF versions but there is SIMPLE and PIMPLE. If you set nOuterCorrectors to 0 or 1 then PIMPLE is operating in PISO mode. The implementation is not hard but I focused some stability problems due to the Pressure-Momentum coupling.

After checking Hagens solver, I saw that he is doing something with the density and compressibility. But till now I had no time to work more on that.

[sino75]

Hi,

I have a question about thermophysical model in Lookup-File. I wanted to create new library for adiabatic flame and got following error:
Maximum number of iteration for calculating temperature from enthalpy.
As i only changed something with the dissipation rates X, the problem must be here. So my question is:
How is the function of T(H,X) defined? I couldn't find the source code for this.

Best regards

(flameletmodel 2.3.x)

[Tobi]

Adiabatic Flamme? You can simulate adiabtic flames.

[sino75]

Sorry, of course I meant PDF for enthalpy defect 0.

[Tobi]

Originally Posted by sino75

Sorry, of course I meant PDF for enthalpy defect 0.

Okay, what you want to do? I did not get the point?

[babakflame]

Greetings Tobi

I hope that you are making good.

I was checking my results of the HM1 bluff-body stabilized flame and confronted a strange behavior. I have compared Temperature results with and without radiation and found that data with radiation indicates partially higher values at rich locations. AFAK from literature, the radiative heat transfer removes enthalpies from high temperature gases, hence, the solution with radiation should give lower temperature .


I have attached a pic of temperature profiles for comparison.


Would u PLZ provide ur suggestions on this behavior?



Best
Bobi

[wenxu]

Dear all,

Anyone in this thread using libOpenSMOKE to simulate soot formation? I want to know how the source library of soot with different models be generated? Any one could give me some hints?

Thank you in advance!


Regards,
Wen Xu

[Tobi]

Originally Posted by wenxu

Dear all,

Anyone in this thread using libOpenSMOKE to simulate soot formation? I want to know how the source library of soot with different models be generated? Any one could give me some hints?

Thank you in advance!


Regards,
Wen Xu

You have to use the original files, there you find the soot library!

[wenxu]

Yes, I am using the original library and I already find the library of soot sources there. BUT I want to know how the library be generated? I did not find the generation tools.

Regards,
Wen Xu

[Tobi]

Which library do you mean? There is only the soot model as source code (as you mentioned). Maybe you mean the flamelet - look - up - table lib.

[wenxu]

No, did not you find the PDF-Library-Soot folder in the original version? There are four sub-folders there: aggregation, growth, nucleation and oxidation.

I mean how did he get the libraries, can they be used for other cases?

Regards,
Wen Xu

[babakflame]

Greetings All

Does anybody has any hint for me about the data driven with and withour radiation written above in post #471.

Best,

[Tobi]

For me its really the Same. The mismatch is so small

[Imed]

Hi Mr Holzmann;
I'm new in OpenFoam, I'd like to simulate flow over cylinder, I generated the mech in GMSH, so Icouldn't convert it to Fuoam, UI cannot know to it wrong...
I'm thankful for your help
...
thank you.

[babakflame]

Originally Posted by Tobi

For me its really the Same. The mismatch is so small

Greetings

Maybe it's just a numerical error.

Best,