[Roxxor91]

Hi all,

I have been struggling with an error for a few days and I don't know what to check anymore.

In my createFields.H, I have 2 lines:

Info << "Correcting model " << nl;
Info << "test1" << nl;

When running my code, it stops at

Correcting model ...

I am puzzled to see that the first Info statement is passed but not the second. Is it a problem of memory ? This occurs whether there is a high memory usage or not.

Thanks in advance for your answers.

[Tobermory]

Umm, I am puzzled as well ... your first Info line prints "Correcting model", which is not the same as the line that you say it gets to ("Creating constitutive model") ... perhaps it is crashing elsewhere?

[Roxxor91]

Originally Posted by Tobermory

Umm, I am puzzled as well ... your first Info line prints "Correcting model", which is not the same as the line that you say it gets to ("Creating constitutive model") ... perhaps it is crashing elsewhere?

Hey, thanks for that remark, I copied the wrong line from my terminal..
I corrected in my post, and what I said remains valid though.

[Tobermory]

Okay - that is strange then. It might be helpful to see what comes before after the two lines that you included. There is surely no memory problem with printing lines to Info, so I wonder whether the second line is buffered for output, but didn't get printed before the run stopped. Are you running this serial or parallel?

You could always try putting an exit(0) line after the second line & recompile, to force the code to stop and flush the buffer - that will tell you if it made it past the second line or not.

Otherwise, there must be something else that is causing the problem.

[Roxxor91]

Originally Posted by Tobermory

Okay - that is strange then. It might be helpful to see what comes before after the two lines that you included. There is surely no memory problem with printing lines to Info, so I wonder whether the second line is buffered for output, but didn't get printed before the run stopped. Are you running this serial or parallel?

You could always try putting an exit(0) line after the second line & recompile, to force the code to stop and flush the buffer - that will tell you if it made it past the second line or not.

Otherwise, there must be something else that is causing the problem.

I have to tell you that it's a solver of my own that has very little to do with classic OpenFOAM solvers. And it's serial at the moment.

I have changed some lines in the code, and now I am able to run the simulation a bit further. Although I cannot confirm at 100% there was no division by 0, if there actually was then the crash would not occur between two Info statements..

So a bit of an update: I am able to run the simulation up to a certain point. With my fine mesh and a CFL of 0.3, it crashes at

Time Step =26
 deltaT = 6.495373218822619e-05 s
 Time = 0.001688669040940589 s
 Simulation completed = 84.433% - Clock = 14s
Post Processing ...
L2errorLM = 0.03768430191941113
L2errorP_ = 0.0218538063768106

Time Step =27
 deltaT = 6.49543441287486e-05 s
 Time = 0.001753623385069337 s

If I change the CFL to 0.2, this is where it crashes:

Time Step =26
 deltaT = 4.329966609208541e-05 s
 Time = 0.001125754647590129 s
 Simulation completed = 56.288% - Clock = 14s
Post Processing ...
L2errorLM = 0.02622370505848511
L2errorP_ = 0.007653927455782624

Time Step =27
 deltaT = 4.32998451625767e-05 s
 Time = 0.001169054492752705 s

If I change the CFL to 0.1, this is where it crashes:

Time Step =26
 deltaT = 2.164901948667259e-05 s
 Time = 0.0005628702820208933 s
 Simulation completed = 28.144% - Clock = 13s

Time Step =27
 deltaT = 2.164904018477349e-05 s
 Time = 0.0005845193222056668 s

The folllowing is the code snippet where it crashes, including the time loop:

    while (runTime.loop())
    {
        if (timeStepping == "variable")
        {
            stretch = mech.stretch();
            scalar minStretch = GREAT;
            forAll(stretch, n) { if (stretch[n] < minStretch) { minStretch = stretch[n]; } }
            deltaT = (cfl*h)/(model.Up()/minStretch);
            runTime.setDeltaT(deltaT);   //Info << "minimum stretch: " << minStretch << nl;
        }
        t += deltaT; tstep++;

        Info << "\nTime Step =" << tstep << "\n deltaT = " << deltaT.value() << " s"
             << "\n Time = " << t.value() << " s" << endl;

        x.oldTime();
        xw.oldTime();

You can notice that I crash always at the same iteration, how weird is this ?

[Tobermory]

Originally Posted by Roxxor91

You can notice that I crash always at the same iteration, how weird is this ?

Thomas, I think you have entered the twilight zone ...

[Roxxor91]

Originally Posted by Tobermory

Thomas, I think you have entered the twilight zone ...

Guide me to the light, great wizard !


On a serious note, I just tried again today and still the problems persists. I can run other cases, with more elements, and more complex physics, and it will work.

[Tobermory]

... and it always crashes on iteration 27? Are you storing in memory data from each iteration? I am wondering whether one of your arrays is going out of bounds ... otherwise, difficult to comment further without seeing all the code.

If you have the patience, you could compile it with debugging, and run a debugger to see exactly what is happening. Not a quick task, but it might provide a way out ... again, good luck.