CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

How to run cold flow in reactingFoam?

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   June 14, 2014, 20:03
Default How to run cold flow in reactingFoam?
  #1
New Member
 
Harshad Lalit
Join Date: May 2013
Posts: 26
Rep Power: 4
harshad88 is on a distinguished road
Hello all,

I have just started using OpenFoam for my dissertation on jet flame calculations. I am trying to simulate axisymmetric cold flow in reactingFoam.

I switched off chemistry and reactions in the "constants" folder to simulate cold flow. Is that the correct way to go about doing it ?

Also even if I switch off my chemistry, i still have default product species H2O and CO2 as output files. Why is that?

Would really appreciate any help. Thanks
harshad88 is offline   Reply With Quote

Old   June 15, 2014, 07:39
Default
  #2
Senior Member
 
Bobi
Join Date: Oct 2012
Posts: 286
Rep Power: 5
babakflame is on a distinguished road
Greetings Harshad

I really didn't get what is exactly your problem. You have switched off the combustion and want to get rid off CO2 and H2O species in results?? (why does it matter)

I think you have used one-step reaction in your case i.e. sth like this:

Code:
species
(
    O2
    H2O
    CH4
    CO2
    N2
);

reactions
{
    methaneReaction
    {
        type         irreversibleArrheniusReaction;
        reaction     "CH4 + 2O2 = CO2 + 2H2O";
        A            5.2e16;
        beta         0;
        Ta           14906;
    }
}
In this case, although you have switched off combustion, you will have zero values for these species in paraview. In case of need to not see these species (I don't know really why) ,I propose to change your combustion model in combustionProperties file to noCombustion. I think (not sure) that this will solve your problem .

Regards
Bobi
babakflame is offline   Reply With Quote

Old   June 16, 2014, 00:31
Default
  #3
New Member
 
Harshad Lalit
Join Date: May 2013
Posts: 26
Rep Power: 4
harshad88 is on a distinguished road
Thanks Bobi!, appreciate your help

I didnt check the CO2 and H2O species files. I was just confused about why they were output when I was solving a cold flow solution.

Can you also let me know how is the perfect gas equation of state used in a combustion solver in OpenFoam? I am assuming that since reactingFoam is a compressible solver, rho would be obtained from the continuity, velocity from the momentum equations and pressure, temperature from a laplacian and the enthalpy respectively.

How is the equation of state used then?
harshad88 is offline   Reply With Quote

Old   June 16, 2014, 03:43
Default
  #4
Senior Member
 
Bobi
Join Date: Oct 2012
Posts: 286
Rep Power: 5
babakflame is on a distinguished road
Greetings Harshad

There is a difference between rhoReactingFoam and reactingFoam solvers. In reactingFoam, rho equation is not solved (although it uses compressible LES sub-grid scale models) and the density is computed from the equation of state. However, in rhoReactingFoam rho equation is solved. (take a look at their src solvers i.e. reactingFoam.C and rhoReactingFoam.C )

Regards
Bobi
babakflame is offline   Reply With Quote

Old   August 6, 2014, 11:56
Default
  #5
Senior Member
 
dkxls's Avatar
 
Armin
Join Date: Feb 2011
Location: Helsinki, Finland
Posts: 152
Rep Power: 10
dkxls will become famous soon enough
Quote:
Originally Posted by babakflame View Post
There is a difference between rhoReactingFoam and reactingFoam solvers. In reactingFoam, rho equation is not solved (although it uses compressible LES sub-grid scale models) and the density is computed from the equation of state. However, in rhoReactingFoam rho equation is solved. (take a look at their src solvers i.e. reactingFoam.C and rhoReactingFoam.C )
I just started to look into this and was wondering if you could quickly elaborate why the rhoEqn is not solved in the reactingFoam solver?

From what I see, in both solvers the actual equation is included in the source code (in the .C files, as well as in the respective pEqn.H files):
Code:
#include "rhoEqn.H"
Thanks!

-Armin
dkxls is offline   Reply With Quote

Old   July 31, 2015, 09:07
Default Why can't I see the velocity residuals in my log file?
  #6
New Member
 
Lisandro Maders
Join Date: Feb 2013
Posts: 28
Rep Power: 4
Lisandro Maders is on a distinguished road
Hello,

I am running a simulation using reactingFoam. There is an inlet of fuel and an inlet of air. After running everything ok, I can't see the velocity residuals in my log file. Why?

Code:
Courant Number mean: 0.0774694 max: 0.394132
deltaT = 0.00116279
Time = 1.5

diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for O2, Initial residual = 9.8746e-07, Final residual = 9.8746e-07, No Iterations 0
DILUPBiCG:  Solving for H2O, Initial residual = 9.79843e-07, Final residual = 9.79843e-07, No Iterations 0
DILUPBiCG:  Solving for CH4, Initial residual = 5.35224e-08, Final residual = 5.35224e-08, No Iterations 0
DILUPBiCG:  Solving for CO2, Initial residual = 9.79228e-07, Final residual = 9.79228e-07, No Iterations 0
DILUPBiCG:  Solving for h, Initial residual = 9.8117e-07, Final residual = 9.8117e-07, No Iterations 0
min/max(T) = 300, 1960.5
DICPCG:  Solving for p, Initial residual = 1.47541e-06, Final residual = 8.87219e-07, No Iterations 21
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 7.03266e-08, global = -9.27209e-10, cumulative = -1.08985e-05
DICPCG:  Solving for p, Initial residual = 1.90516e-06, Final residual = 6.1582e-07, No Iterations 1
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 7.03245e-08, global = -9.37162e-10, cumulative = -1.08994e-05
ExecutionTime = 19.53 s  ClockTime = 19 s

Regards,

Lisandro
Lisandro Maders is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
flow over a cylinder urgent! kevin FLUENT 8 August 11, 2015 13:00
Unable to run lid-driven cavity flow with 1M elements dougalb OpenFOAM Running, Solving & CFD 1 October 18, 2013 02:31
Cold FLow analysis in Gas Turbine..Help Needed juzer_700 FLUENT 8 September 30, 2013 02:47
ATTENTION! Reliability problems in CFX 5.7 Joseph CFX 14 April 20, 2010 15:45
good Cold Flow Results but problem with Hot Flow Rams FLUENT 1 June 18, 2006 19:59


All times are GMT -4. The time now is 15:36.