Blog : OpenFOAM(R) field names

Recently, there was a problem with units:

--> FOAM FATAL ERROR: (openfoam-2312)
Different dimensions for '(a = b)'
     dimensions : [0 2 -1 0 0 0 0] != [1 -1 -1 0 0 0 0]

Obviously, the problem is with the division by density, and it is located in

#5  Foam::EddyDiffusivity<Foam::ThermalDiffusivity<Foam::CompressibleTurbulenceModel<Foam::multiphaseInter::multiphaseSystem> > >::correctNut()

So, it seems, the problem is with the nut units. Yet, at a closer analysis, the problem was with the field alphat:

template<class BasicTurbulenceModel>
void Foam::EddyDiffusivity<BasicTurbulenceModel>::correctNut()
{
    // Read Prt if provided
    Prt_ = dimensionedScalar("Prt", dimless, 1.0, this->coeffDict());
    alphat_ = this->rho_*this->nut()/Prt_;
    alphat_.correctBoundaryConditions();
}

However, if we consider nut as a diffusivity of momentum and alphat as a diffusivity of heat, we can call alphat “nut”.