regionCoupledTemperatureJump

Overview

regionCoupledTemperatureJump is the value side (Dirichlet side) of the temperature coupling of heatTransferInterface, used for conjugate heat transfer and thermo-FSI. It derives from genericRegionCoupledJump<scalar> (and so from fixedValue). It fixes the patch temperature to the neighbour temperature, interpolated onto this patch and scaled by the interface’s jumpCoefficient $c$ ($c = 1$: temperature continuity). It also supplies its heat flux $\kappa\,\partial T/\partial n$ to the partner regionCoupledHeatFlux on the neighbour region. The interface found through the first interfaceType entry must be a heatTransferInterface.

Mathematical Formulation

Let $A$ be this patch and $B$ the neighbour (flux-side) patch:

implemented as $T_A = \mathcal{I}_{B\to A}(T_B) + j$ with

followed by relaxation with the acceleration model. The heat flux handed to regionCoupledHeatFlux is

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

Implementation

Run-time work is inherited from genericRegionCoupledJump<scalar> (see there). The class adds:

• valueJump(): looks up the neighbour T under the local field name, interpolates its neighbour patch values, and returns $\mathcal{I}(T_B)\,(c - 1)$. Here $c$ is heatTransInterface().jumpCoefficient().value(), a single scalar.
• heatTransInterface(): checks that the interface matched through the first interfaceType entry has type heatTransferInterface, otherwise FatalError (“BC can only be used in combination with a heatTransferInterface”). It is called from valueJump(), so the check runs on the first updateCoeffs() and on every residual evaluation.
• diffusivityName(): returns the diffusivity keyword if set, otherwise kappa. diffCoeff() uses the volScalarField with this name on the local region if one is registered, else a uniform dimensionedScalar of that name from the region’s transportProperties.

Per DNA iteration of T: the interface is updated (its correct() is a no-op), the value $\mathcal{I}(T_B) + j$ is set, relaxed (accType, relax) and fixed. The jump residual $|T_A - \mathcal{I}(T_B) - j|$ is checked against maxJumpRes.

Dictionary Entries

Usage

From tutorials/conjugateHeatTransfer/flowOverHeatedPlate/0/fluid/orig/partitioned/T:

interface
{
    type                    regionCoupledTemperatureJump;
    interfaceType           (heatTransferInterface);

    accType                 aitken;
    relax                   0.75;

    secondOrder             false;
    nonOrthCorr             false;
    value                   $internalField;
}

Partner in 0/solid/orig/partitioned/T:

top
{
    type                    regionCoupledHeatFlux;
    interfaceType           (heatTransferInterface);

    secondOrder             false;
    nonOrthCorr             false;
    value                   $internalField;
}

Interface in constant/regionInterfacePropertiesPartitioned:

partitionedCoupledPatches
(
    fluidsolid
    {
        interfaceType (heatTransferInterface);
        coupledPatchPair
        (
            (fluid interface)
            (solid top)
        );
        coupledFields
        (
            T
        );
        heatTransferInterfaceCoeffs
        {
            jumpCoefficient               jumpCoefficient [ 0 0 0 0 0 0 0 ] 1;
        }
    }
);

and the T entry in the DNA block of constant/multiRegionProperties (maxCoupleIter, maxJumpRes, maxFluxRes). For thermo-FSI the interface entry lists interfaceType (fsiInterface heatTransferInterface);, while the T patches keep interfaceType (heatTransferInterface); (tutorials/fluidStructureInteraction/heatedBeamInCrossFlow).

Known Limitations

• Needs heatTransferInterface first in the BC’s interfaceType list; any other type aborts in valueJump().
• Constant, uniform jump coefficient. $c$ is a single dimensionedScalar read once by the interface. The jumpCoefficient patch keyword (field lookup) of regionCoupledScalarJump is not used here.
• No unit check on kappa. The flux balance with the partner only conserves energy if both sides name conductivities in the same units (e.g. not DT in m²/s on one side).
• Missing diffusivity is fatal when the partner first asks for flux() (no kappa field and no kappa in transportProperties).
• Inherited from genericRegionCoupledJump: neighbourFieldName unused, side detection by patch name only, acceleration state carried over time steps, IQNILS not parallel-consistent, partitioned only (the *Monolithic tutorial variants use other BCs).

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