[reytisker]

I want to write a solver that solves a certain PDE, and at each timestep it has to use the Stokes solution of a Navier Stokes equation, for which I can use the simpleFoam solver as a basis (it's basically some kind of reaction diffusion equation for very low Reynolds number). If the simpleFoam main loop is as follows

while(simple.loop(runTime)
{
    #include "UEqn.H"
    #include "pEqn.H"
}

and my equation is solved in another file, "aEqn.h", then the next is wrong

while(simple.loop(runTime)
{
    #include "UEqn.H"
    #include "pEqn.H"
    #include "aEqn.h"
}

since aEqn will use values of U that haven't converged yet. I tried something like what follows, but doesn't work either because I don't know how to have two different runTime loops, one for the U convergence, and another for the real time defined by the time evolution of "aEqn":

while(runTime.loop())
{
    while(simple.loop(??))
    {

        #include "UEqn.H"
        #include "pEqn.H"
    }

    #include "aEqn.h"
}

What would be the proper way to implement this kind of solver?

[mAlletto]

If you want two different loops look at the pimple solver