[serles]

Hello Foamers,

I'm stuck within implementing a set of ODE in OpenFOAM-extend 3.2. The greatest problem is that the extenden version has no Test-ODE.C, at least I couldn't find it. Thus, I implemented my ODEs in OF-2.3, which is working fine, and now try to transfer it to the extend version.

I'm trying to figure out what is the meaning of the "coeffs" function in ODE.H:

        
        //- Return access to coefficients
        virtual scalarField& coeffs() = 0;

        //- Return reference to coefficients
        virtual const scalarField& coeffs() const = 0;

These are abscent in OF-2.3, but here they are pure virtual and must be overloaded. I figured out the at some point in ODESolver.C the function provides y, but y is alredy defined in "derivatives()", which makes no sense to me.

    
scalarField& y = ode_.coeffs();

for (label nStep = 0; nStep < MAXSTP; nStep++)
    {
        ode_.derivatives(x, y, dydx_);

        for (label i=0; i<nEqns; i++)
        {
            yScale_[i] = mag(y[i]) + mag(dydx_[i]*h) + SMALL;
        }

        if ((x + h - xEnd)*(x + h - xStart) > 0.0)
        {
            h = xEnd - x;
        }

        scalar hNext, hDid;
        solve(x, y, dydx_, eps, yScale_, h, hDid, hNext);

What should I put in the definition of these "coeffs" functions?

Can anybody provide a simple test case for the current OpenFOAM-extend version (something like Test-ODE)?

[giovastabile]

Hi I'm also havin the same issues.. did you maybe find a solution?

Regards,

Giovanni

[serles]

Hey Giovanno,
I couldn't really figure out how it was meant to be done but I brought it to tun.
Now I think "coeffs" function is about starting values for your ODE or at least initializing the variable "y". So a fast solution would be to put there something which intitializes your scalarfield y and returns it back. It needs only to compile, it will not affect your solution (IMHO)

In my case, I needed also to change some routines in ODESolver and thus I just copied the whole ODE directory to my solver directory, changed and compiled it. Here you need to make sure that you include only your version of ODE directory for compiler under Make/options: EXE_INC = -I./ODE and also you have to mention all the .C files in the file Make/files: ODE/ODESolver.C; ODE/RK.C ... (ans so on)

Hope this helps!
Greets,
Sergey

[giovastabile]

Dear Sergey,

Thank you for the prompt answer, I had also the same idea and I compared the code with the codes from standard versions of OpenFOAM. It looks that it is not used inside the routines. I will try to do as you mentioned.

Regards,

Giovanni