regionCoupledScalarJump

Overview

regionCoupledScalarJump is the concrete scalar value side (Dirichlet side) of the partitioned DNA coupling. It derives from genericRegionCoupledJump<scalar> (and so from fixedValue). It fixes the patch value to the neighbour value interpolated onto this patch, scaled by a jump (partition) coefficient $c$, which defaults to 1, i.e. continuity. It does not check the interface type, so it works with any interface, in practice defaultInterface. It is the generic choice for potentials, temperatures and concentrations that need no interface physics. The partner on the neighbour patch is regionCoupledScalarFlux (or any other genericRegionCoupledFlux<scalar>-derived BC, e.g. regionCoupledPhaseChangeHeatFlux).

Mathematical Formulation

Let $J$ be this patch and $F$ the neighbour (flux-side) patch:

implemented as $\phi_J = \mathcal{I}_{F\to J}(\phi_F) + j$ with the value jump

The value is then relaxed by the acceleration model. The flux handed to the partner is

with the coupled snGrad of genericRegionCoupledJump (optional non-orthogonal and second-order corrections).

Implementation

All run-time work (interface lookup, updateCoeffs(), relaxation, snGrad, flux(), diffCoeff(), residuals) is inherited from genericRegionCoupledJump<scalar>. The class only implements valueJump():

1. Looks up the neighbour field under the local field name and interpolates its neighbour patch values onto this patch.
2. Determines $c$ per face:
   • if a volScalarField named jumpCoefficient is registered on the local region, its local patch values are used;
   • else, if jumpCoefficient is set, a uniform dimensionedScalar of that name is read from the local region’s transportProperties;
   • else $c = 1$.
3. Returns $\mathcal{I}_{F\to J}(\phi_F)\,(c - 1)$.

valueJump() is evaluated in updateCoeffs() and again in each residual evaluation (jump residual $|\phi_J - \mathcal{I}(\phi_F) - j|$, checked against maxJumpRes).

Dictionary Entries

Usage

From tutorials/electrochemistry/NTGKBatteryWithTabs/0/posTabRegion/orig/partitioned/phiPos (jump side on the tab):

toCellFromPos
{
    type                    regionCoupledScalarJump;
    interfaceType           (defaultInterface);
    diffusivity             "sigma";
    accType                 aitken;
    relax                   0.1;
    secondOrder             false;
    nonOrthCorr             false;
    value                   $internalField;
}

Partner in 0/batteryRegion/orig/partitioned/phiPos:

toPosTab
{
    type                    regionCoupledScalarFlux;
    interfaceType           (defaultInterface);
    diffusivity             "sigmaPos";
    secondOrder             false;
    nonOrthCorr             false;
    value                   $internalField;
    gradient                uniform 0.1266;
}

Interface entry in constant/regionInterfaceProperties:

cellToPosTab
{
    interfaceType (defaultInterface);
    coupledPatchPair
    (
        (batteryRegion toPosTab)
        (posTabRegion  toCellFromPos)
    );
    coupledFields
    (
        phiPos
        phiNeg
        T
    );
    defaultInterfaceCoeffs
    {}
}

and a DNA entry per coupled field in constant/multiRegionProperties:

DNA
{
    phiPos
    {
        maxCoupleIter 50;
        residualControl
        {
            maxJumpRes 1e-05;
            outputJumpResField no;
            maxFluxRes 1e-05;
            outputFluxResField no;
        }
    }
}

For a partition coefficient (e.g. Henry’s law $C_A = H\,C_B$), add jumpCoefficient H; and provide H either as a volScalarField on the jump-side region or as H H [0 0 0 0 0 0 0] 0.5; in its transportProperties.

Known Limitations

• No interface-type check. Any interface type listed first in interfaceType is accepted. The interface’s own physics, if any, is not used, except that its correct() is called through update().
• diffusivity must be set. The default word::null makes the diffCoeff() lookup in transportProperties fail as soon as the partner asks for flux().
• Diffusivities are not checked for consistency. Each side uses whatever its diffusivity names (in NTGK, sigmaPos on the battery and sigma on the tab). Flux conservation requires the same units on both sides.
• Jump coefficient is taken from the jump side only (local field or local transportProperties). With a volScalarField, the local patch values are used and not interpolated.
• jumpCoefficient is not written by write(), so it disappears from written time directories and after decomposePar.
• Inherited limitations of genericRegionCoupledJump: neighbourFieldName unused, side detection by patch name only, IQNILS not parallel-consistent, partitioned only.

Tutorials

References

• Alkfri, A., Habes, C., Marschall, H., multiRegionFoam: A Unified Multiphysics Framework for Multi-Region Coupled Continuum-Physical Problems, Engineering with Computers, 2023. DOI: 10.1007/s00366-024-01974-4