regionCoupledMassTransferPressureValue

Overview

regionCoupledMassTransferPressureValue is the Dirichlet (jump) half of the partitioned pressure coupling across a sharp liquid-vapour interface with phase change. It acts on a volScalarField (p or pKin) and derives from genericRegionCoupledJump<scalar>, i.e. from fixedValue. It applies the same normal-stress jump as regionCoupledPressureValue and adds the recoil pressure $-(1/\rho_\text{own}-1/\rho_\text{nbr})\,\dot m^2$. There is no mass-transfer pressure-flux BC; the partner is presumably regionCoupledPressureFlux (inferred). The BC needs a capillaryInterface as the first interfaceType entry and a massTransferInterface on the same patch pair.

Mathematical Formulation

The BC sits on side A (“own”), which carries the faMesh of the capillaryInterface; “nbr” is side B. $\tilde{\dot m} = \mathcal{I}_{\text{nbr}\to\text{own}}(\dot m)$.

For a field named p:

For a field named pKin:

followed by relaxation, $p^{k} = p^{k-1} + \omega\,(p^{*} - p^{k-1})$.

Implementation

updateCoeffs() is the generic one of genericRegionCoupledJump: return if updated or coupled no; call update() on the first interfaceType (the capillaryInterface); interpolate the neighbour field (looked up by the local field name); add valueJump(); relax; call fixedValue::updateCoeffs().

valueJump() is that of regionCoupledPressureValue with the extra recoil term. It aborts unless the first interfaceType is capillaryInterface, finds the massTransferInterface by type name and interpolates mDotS() from the neighbour side. PISO.pRefPoint, g, and mu/rho of both regions are required. The mesh flux and patch normals are computed but not used.

Since only the first interface is update()d, $\dot m$ is not recomputed by this BC. It changes only when a BC that lists massTransferInterface first (e.g. regionCoupledPhaseChangeHeatFlux on T) is updated. Until then the recoil term is zero and the BC behaves like regionCoupledPressureValue.

The p jump residual of the pUPimple DNA loop is taken from this BC (side A is checked first). flux() uses the hardcoded diffusivity v, for which diffCoeff() returns $\rho$ instead of $1/\rho$ (1 for pKin); the partner regionCoupledPressureFlux cancels this flux.

Dictionary Entries

Entries read from other files: PISO { pRefPoint (...); } in the local fvSolution, g in the local constant/, and mu, rho in transportProperties of both regions.

Usage

No tutorial uses this BC. Untested entry on side A, following massTransferInterface:

// 0/fluidA/p
interface
{
    type                    regionCoupledMassTransferPressureValue;
    interfaceType           (capillaryInterface massTransferInterface);
    secondOrder             false;
    nonOrthCorr             false;
    value                   uniform 0;
}

Partner on side B (inferred):

// 0/fluidB/p
interfaceShadow
{
    type                    regionCoupledPressureFlux;
    interfaceType           (capillaryInterface massTransferInterface);
    value                   uniform 0;
}

The regionInterfaceProperties entry is shown on the regionCoupledMassTransferVelocityValue page and in massTransferInterface.

Known Limitations

• Untested, no tutorial; the intended region type interTrackFluid is disabled.
• $\dot m$ is only updated through another BC. See Implementation.
• mDotS() is interpolated from the neighbour although it is defined on side A (inferred), where this BC sits. Harmless only for identical conformal patches.
• Must sit on side A (inferred): $\sigma$, $\kappa$ and $\nabla_s\cdot\mathbf{u}_s$ are used without interpolation.
• No dedicated flux partner. regionCoupledPressureFlux does not account for phase change.
• Constant properties, PISO.pRefPoint required, diffusivity and neighbourFieldName ignored (as for regionCoupledPressureValue).

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