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  • Will Bainbridge's avatar
    ENH: semiPermeableBaffle: Added two new boundary conditions and a tutorial · 1bf31fb9
    Will Bainbridge authored and Andrew Heather's avatar Andrew Heather committed
    Two boundary conditions for the modelling of semi-permeable baffles have
    been added. These baffles are permeable to a number of species within
    the flow, and are impermeable to others. The flux of a given species is
    calculated as a constant multipled by the drop in mass fraction across
    the baffle.
    
    The species mass-fraction condition requires the transfer constant and
    the name of the patch on the other side of the baffle:
    
    boundaryField
    {
        // ...
    
        membraneA
        {
            type            semiPermeableBaffleMassFraction;
            samplePatch     membranePipe;
            c               0.1;
            value           uniform 0;
        }
        membraneB
        {
            type            semiPermeableBaffleMassFraction;
            samplePatch     membraneSleeve;
            c               0.1;
            value           uniform 1;
        }
    }
    
    If the value of c is omitted, or set to zero, then the patch is
    considered impermeable to the species in question. The samplePatch entry
    can also be omitted in this case.
    
    The velocity condition does not require any special input:
    
    boundaryField
    {
        // ...
    
        membraneA
        {
            type            semiPermeableBaffleVelocity;
            value           uniform (0 0 0);
        }
        membraneB
        {
            type            semiPermeableBaffleVelocity;
            value           uniform (0 0 0);
        }
    }
    
    These two boundary conditions must be used in conjunction, and the
    mass-fraction condition must be applied to all species in the
    simulation. The calculation will fail with an error message if either is
    used in isolation.
    
    A tutorial, combustion/reactingFoam/RAS/membrane, has been added which
    demonstrates this transfer process.
    
    This work was done with support from Stefan Lipp, at BASF.
    1bf31fb9