[pablitobass]

Hello everyone,

I would like to ask some advices about the implementation of a new tensor into the constructor of an existing code.

I have already created the tensor as an IOobject. The tensor sigma_ into this code:

tau_
    (
        IOobject
        (
            "tau" + name,
            U.time().timeName(),
            U.mesh(),
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        U.mesh()
    ),  
    sigma_
    (
        IOobject
        (
            "sigma" + name,
            U.time().timeName(),
            U.mesh(),
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        U.mesh()
    ),
    I_
    (
        dimensionedSymmTensor
        (
            "I",
            dimensionSet(0, 0, 0, 0, 0, 0, 0),
            symmTensor
            (
                1, 0, 0,
                   1, 0,
                      1
            )
        )
    ),
    rho_(dict.lookup("rho")),
    etaS_(dict.lookup("etaS")),
    etaP_(dict.lookup("etaP")),
    lambda_(dict.lookup("lambda"))
{
   sigma_ = lambda_ * tau_ / etaP_ + I_;
}

In this way I am obliged to create a "0" folder file for sigma. I did it, but since the boundary condition for this tensor are unknown, the results I got so far are wrong. In practice I would like just to define the tensor and calculate its value from the equation that is shown at the end of the previous piece of code, that is

sigma_ = lambda_ * tau_ / etaP_ + I_;

Does anyone have an idea on how to do this?
p.s I have tried to use the options: IOobject::NO_READ, and IOobject::READ_IF_PRESENT, but I could not sort the problem out.

Thank you very much.

Cheers,
Paolo