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-   -   ODE solver for reactingFoam (http://www.cfd-online.com/Forums/openfoam-solving/86899-ode-solver-reactingfoam.html)

narak April 5, 2011 12:10

ODE solver for reactingFoam
 
I ran this test case with simple one step chemistry using different ODE Solvers(SIBS, KRR4, RK). I expected same result but it wasn't.
Maximum temperature is about 2252 K for SIBS, 1446 K for KRR4 and 2570 K for RK.

test case : ReactingFoam/counterFlowFlame2D

odeCoeffs
{
ODESolver RK; //SIBS, KRR4, RK
eps 0.05;
scale 1;
}

================================================== ================

But Results for simple ODE show no difference.

y" - y = 0 ; y(0) = 0, y'(0) = 1

SIBS : Numerical: y(1.0) = 2(1.175190 1.543074), hEst = 1.245250
KRR4 : Numerical: y(1.0) = 2(1.175212 1.543091), hEst = 0.186009
RK : Numerical: y(1.0) = 2(1.175180 1.543062), hEst = 0.665943

- ODEtest(test/ODETest.c)
http://www.tfd.chalmers.se/~hani/kurser/OS_CFD_2008/ZongyuanGu/reportZongyuan.pdf

- Cash-Karp Runge-kutta method in OpenFOAM
http://ftp.eq.uc.pt/books/NumericalRecipes/f16-2.pdf

narak April 13, 2011 05:28

15 step chemistry results
 
I ran the same tutorial test case with 39 step chemistry(C7H16) included in OF and got almost same results.


reactingFoam SIBS KRR4 RK
T_max(K) 1892 1896 1901
dQ_max 0.128 0.130 0.133
*Ext t(s) 1818 1664 54497

* execution time for Time = 1

I don't know why 1 step chemistry showed different results yet, but it seems to run correctly with multi step chemistry including GRI 3.0.

mhsn October 24, 2012 16:34

Regarding your post, you are familiar with using detailed reaction mechanisms (like GriMech 3.0) in OpenFoam. What I'm going to do is to simulate premixed combustion in a small channel using OpenFoam2.1.1. I wonder what solver to use and how to implement full chemistry. I mean, how I can solve conservation equations for all species. Any help would be appreciated.

Traib November 16, 2012 04:53

Quote:

Originally Posted by mhsn (Post 388361)
What I'm going to do is to simulate premixed combustion in a small channel using OpenFoam2.1.1. I wonder what solver to use and how to implement full chemistry. I mean, how I can solve conservation equations for all species. Any help would be appreciated.

Hi mhsn,

You can use reactingFoam, or a density based solver rhoRactingFoam. These are solver application for which the source codes can be easily found here http://www.openfoam.org/docs/cpp/. However, if you meant to ask for a chemistry solver then you can select from the chemestry models listed in the above site.

As for solving the species transport and temperature equations, the solver applications you choose will do it for you.

zqlhzx August 18, 2013 10:13

ODEsolver
 
Hi:
Foamers,Can someone tell me the way of ODE solvers what equation in reactingFoam?Is UEqn or hEqn?


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