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Tutorial problem sonicTurbFoamnacaAirfoil

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Old   March 18, 2008, 01:47
Default Hello. I am new to OpenFOAM a
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Jeremiah Hall
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Hello. I am new to OpenFOAM and am trying to go through some tutorials to get a feel for how everything works. I've done a couple of the simple ones, and now I'm having trouble with the naca airfoil. I have set the inlet to supersonicFreestream, and then I set Uinf to the value that already existed in the internal field value. Now, when I go to the INLE1 parameters for U, there are inputs for pinf, Tinf, Uinf, and something simply called value. Value has inputs for x, y, and z, so I figured it was velocity vector and entered the same numbers as Uinf.

Now, when I try to run, I get :

--> FOAM FATAL IO ERROR : keyword gamma is undefined in dictionary "/home/jjhall/OpenFOAM/jjhall-1.4.1/run/tutorials/sonicTurbFoam/nacaAirfoil/0/U: :INLE1"

I also looked through the thermophysical properties, and did not see any place where gamma is defined.

Could someone tell me if I am setting "value" incorrectly, and what it means? Or, if not, what am I doing wrong?

Thanks,

Jeremiah
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Old   March 18, 2008, 01:49
Default By the way, here is nacaAirfoi
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Jeremiah Hall
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By the way, here is nacaAirfoil/0/U :

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \ / O peration | Version: 1.4.1 |
| \ / A nd | Web: http://www.openfoam.org |
| \/ M anipulation | |
\*---------------------------------------------------------------------------*/

// Field Dictionary

FoamFile
{
version 2.0;
format ascii;

root "/home/jjhall/OpenFOAM/jjhall-1.4.1/run/tutorials/sonicTurbFoam";
case "nacaAirfoil";
instance "0";
local "";

class volVectorField;
object U;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //


dimensions [0 1 -1 0 0 0 0];

internalField uniform (600 148.16 0);

boundaryField
{
INLE1
{
type supersonicFreestream;
pInf 100000;
TInf 300;
UInf (600 148.16 0);
value uniform (600 148.16 0);
}

OUTL2
{
type zeroGradient;
}

SYMP3
{
type symmetryPlane;
}

WALL10
{
type fixedValue;
value uniform (0 0 0);
}
}


// ************************************************** *********************** //
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Old   March 18, 2008, 04:44
Default In this case you just have to
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Maximilian Graser
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In this case you just have to read the error-message
It says that there is a keyword "gamma" missing in your file:
/home/jjhall/OpenFOAM/jjhall-1.4.1/run/tutorials/sonicTurbFoam/nacaAirfoil/0/U
at the patch:
INLE1

I simply would define a new keyword there named "gamma" and set it like the others (as you can read in the User Manual gamma describes the ratio between gas and liquid e.g. 0 = 100% gas / 1 = 100% liquid)
It could for examle look like this:
...
INLE1
{
type supersonicFreestream;
pInf 100000;
TInf 300;
UInf (600 148.16 0);
gamma 0;
value uniform (600 148.16 0);
}
...
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Old   March 18, 2008, 10:21
Default Thanks for the reply. I did i
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Jeremiah Hall
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Thanks for the reply. I did implement this change, except when I used gamma = 0, I got a long list of errors. I changed it to gamma = 1.4, and now it is running fine (at the moment).

I am a little bit confused with this issue because I am using FoamX to set up the case. I had expected that FoamX would recognize the boundary condition type and properly create all of the necessary input variables, but gamma was not an option to set. Is this a bug in FoamX? Or am I just doing something wrong?

Thanks,

Jeremiah
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Old   March 18, 2008, 10:30
Default By the way, I now have a diffe
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Jeremiah Hall
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By the way, I now have a different problem. sonicTurbFoam has crashed:

--> FOAM FATAL ERROR : Maximum number of iterations exceeded#0 Foam::error::printStack(Foam:stream&) in "/home/jjhall/OpenFOAM/OpenFOAM-1.4.1/lib/linux64GccDPOpt/libOpenFOAM.so"

I see at the end of the sonicTurbFoam.log that there are "time step continuity errors" on the time step before the crash. Also, it says that it is bounding epsilon, with a range of approx. -10^28 to +10^28. Is the crash coming from large values of epsilon, or some issue with the time step continuity?
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Old   March 19, 2008, 05:05
Default Hello Jeremiah Concerning Foa
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Maximilian Graser
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Hello Jeremiah
Concerning FoamX I noticed that sometimes it is not up to date with the solvers or boundary conditions. But I have to say...I don't care because I'm nt using FoamX. Therefore you would need help from a more experienced user of this board.

The "time step continuity errors" are calculated and printed every timestep. They can be usefull to observe how your calculation converges. Therefore the size of the residuals should be what you're looking at. As you can see there are 3 different types of residuals "sum local", "global" and "comulative". Unfortunately I don't really know what they exactly mean , I hope some more experienced user can help with this.

In my opinion the crash is coming from the large values of epsilon. Maybe you should try some other values for epsilon and k at your boundarys (you could for example calculate them). I also experienced that you get better convergence with a decent initiation of your internal field (use potentialFoam and/or lower viscosity; search the board).

Max
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Old   March 19, 2008, 09:21
Default Thanks for the advice, Max. I
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Jeremiah Hall
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Thanks for the advice, Max. I kind of suspected that the large values of epsilon were the culprit. I will try to use potentialFoam to initialize the field, and set the inlet of epsilon smaller (I had just used the internal field value that was already set up).

Does anyone know if there is a possibility to limit epsilon? At work I run GASP, with a k-omega model, and I enforce a limit on omega. Is there a possibility for this in OpenFOAM?

Thanks,

Jeremiah
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