InterfaceKernels System
Interface kernels are meant to assist in coupling different physics across sub-domains. The most straightforward example is the case in which one wants to set the flux of a specie A in subdomain 0 equal to the flux of a specie B in subdomain 1 at the boundary between subdomains 0 and 1. In mathematical terms, we might be interested in establishing the condition:
where is the diffusion coefficient of specie in subdomain , and is the concentration of specie in subdomain . An example of this condition is shown in the MOOSE test directory; see files below:
(test/tests/interfacekernels/2d_interface/coupled_value_coupled_flux.i)
(framework/src/interfacekernels/InterfaceDiffusion.C)
(framework/include/interfacekernels/InterfaceDiffusion.h)
Interface kernels can be used to provide any general flux condition at an interface, and even more generally can be used to impose any interfacial condition that requires access to values of different variables and gradients of different variables on either side of an interface. In an input file, the user will specify at a minimum the following parameters:
type: The type of interface kernel to be usedvariable: This is the "primary" variable. Note that the primary variable must exist on the same subdomain as the sideset specified in theboundaryparameter. The existence of a "primary" and "secondary" or "neighbor" variable ensures that the interface kernel residual and jacobian functions get called the correct number of times.variablecould be from our example above.neighbor_var: The "secondary" variable. This could be from our example above.boundary: The interfacial boundary between the subdomains. Note that this must be a sideset and again must exist on the same subdomain as the primary variable. The fact that this boundary is a sideset allows access to variable gradients.
An important private parameter relevant to displaced mesh calculations is _use_undisplaced_reference_points. If an interface kernel developer sets this parameter to true in the validParams of their derived class, then the displaced problem will use the neighbor reference points computed by the undisplaced problem as the neighbor reference points for the displaced problem. If this parameter is false (the default), then the neighbor reference points on the displaced problem will be computed in the traditional way: by doing an inverse map of the physical locations of the displaced element reference points. Here, reference refers to the reference coordinates (e.g. and ) of the quadrature points and physical refers to the physical coordinates (e.g. and ) of the quadrature points.
For additional information about the interface kernel system, don't hesitate to contact the MOOSE Discussion forum.
Available Objects
- Moose App
- InterfaceDiffusionThe kernel is utilized to establish flux equivalence on an interface for variables.
- InterfaceReactionImplements a reaction to establish ReactionRate=k_f*u-k_b*v at interface.
- PenaltyInterfaceDiffusionA penalty-based interface condition that forcesthe continuity of variables and the flux equivalence across an interface.
- Heat Conduction App
- ConjugateHeatTransferThis InterfaceKernel models conjugate heat transfer. Fluid side must be primary side and solid side must be secondary side. T_fluid is provided in case that variable ( fluid energy variable) is not temperature but e.g. internal energy.
- SideSetHeatTransferKernelModeling conduction, convection, and radiation across internal side set.
- Tensor Mechanics App
- CZMInterfaceKernelSmallStrainCZM Interface kernel to use when using the Small Strain kinematic formulation.
- CZMInterfaceKernelTotalLagrangian
- Phase Field App
- EqualGradientLagrangeInterfaceEnforce componentwise gradient continuity between two different variables across a subdomain boundary using a Lagrange multiplier
- EqualGradientLagrangeMultiplierLagrange multiplier kernel for EqualGradientLagrangeInterface.
- InterfaceDiffusionBoundaryTermAdd weak form surface terms of the Diffusion equation for two different variables across a subdomain boundary
- InterfaceDiffusionFluxMatchEnforce flux continuity between two different variables across a subdomain boundary
- Fsi App
- CoupledPenaltyInterfaceDiffusionEnforces continuity of flux and continuity of solution via penalty across an interface.
- StructureAcousticInterfaceEnforces displacement and stress/pressure continuity between the fluid and structural domains. Element is always the structure and neighbor is always the fluid.
Available Actions
- Moose App
- AddInterfaceKernelActionAdd an InterfaceKernel object to the simulation.