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:

(moose/test/tests/interfacekernels/2d_interface/coupled_value_coupled_flux.i)

(moose/framework/src/interfacekernels/InterfaceDiffusion.C)

(moose/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 used

  • variable: This is the "primary" variable. Note that the primary variable must exist on the same subdomain as the sideset specified in the boundary parameter. 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. variable could 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.

For additional information about the interface kernel system, don't hesitate to contact the MOOSE Discussion forum.

Multiple system support

Using multiple nonlinear system with interface kernels is currently not supported. The only feature supported, which can at times suffice, notably when using MultiApps to couple equations, is to use an auxiliary variable as the neighbor_var.

Available Objects

  • Moose App
  • ADMatInterfaceReactionImplements a reaction to establish ReactionRate=k_f*u-k_b*v at interface.
  • ADPenaltyInterfaceDiffusionA penalty-based interface condition that forcesthe continuity of variables and the flux equivalence across an interface.
  • ADVectorPenaltyInterfaceDiffusionA penalty-based interface condition that forcesthe continuity of variables and the flux equivalence across an interface.
  • 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.
  • VectorPenaltyInterfaceDiffusionA penalty-based interface condition that forcesthe continuity of variables and the flux equivalence across an interface.
  • Zapdos App
  • HphiRadialInterface
  • InterfaceAdvectionUsed to include the electric field driven advective flux of speciesinto or out of a neighboring subdomain. Currently this interface kernelis specific to electrons because the transport coefficients are assumedto be a function of the mean electron energy. A generic interfacekernel with constant transport coefficients will have a much simpler Jacobian
  • InterfaceLogDiffusionElectronsUsed to include the diffusive flux of species into or out of a neighboringsubdomain. Currently specific to electrons.
  • PotentialSurfaceCharge
  • Squirrel App
  • InterTemperatureAdvectionDG upwinding for the convection

Available Actions