CoupledTimeDerivative

Description

The CoupledTimeDerivative kernel is very similar to the TimeDerivative kernel with the exception that the time derivative operator is applied to a coupled variable instead of the variable to whom's residual the CoupledTimeDerivative kernel contributes. Consequently, the strong form on the the domain is

(1) where the second term on the left hand side corresponds to the strong forms of other kernels. The CoupledTimeDerivative weak form is then

(2) where the are test functions and is the finite element solution of the weak formulation.

The Jacobian contribution is equal to (3) where is a constant that depends on the time stepping scheme; is denoted by _dv_dot in the CoupledTimeDerivative class.

Example Syntax

CoupledTimeDerivative is used for example in the split Cahn Hilliard equations for phase field calculations. The syntax is simple, taking its type (CoupledTimeDerivative), the variable to that the residual the CoupledTimeDerivative contributes, and the coupled variable v that the time derivative operator acts upon. Example syntax can be found in the kernel block below:

test/tests/kernels/coupled_time_derivative/coupled_time_derivative_test.i
block=Kernels label=false

Input Parameters

  • variableThe name of the variable that this Kernel operates on

    C++ Type:NonlinearVariableName

    Options:

    Description:The name of the variable that this Kernel operates on

  • vCoupled variable

    C++ Type:std::vector

    Options:

    Description:Coupled variable

Required Parameters

  • blockThe list of block ids (SubdomainID) that this object will be applied

    C++ Type:std::vector

    Options:

    Description:The list of block ids (SubdomainID) that this object will be applied

Optional Parameters

  • enableTrueSet the enabled status of the MooseObject.

    Default:True

    C++ Type:bool

    Options:

    Description:Set the enabled status of the MooseObject.

  • save_inThe name of auxiliary variables to save this Kernel's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

    C++ Type:std::vector

    Options:

    Description:The name of auxiliary variables to save this Kernel's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

  • use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

    Default:False

    C++ Type:bool

    Options:

    Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

  • control_tagsAdds user-defined labels for accessing object parameters via control logic.

    C++ Type:std::vector

    Options:

    Description:Adds user-defined labels for accessing object parameters via control logic.

  • seed0The seed for the master random number generator

    Default:0

    C++ Type:unsigned int

    Options:

    Description:The seed for the master random number generator

  • diag_save_inThe name of auxiliary variables to save this Kernel's diagonal Jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

    C++ Type:std::vector

    Options:

    Description:The name of auxiliary variables to save this Kernel's diagonal Jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

  • implicitTrueDetermines whether this object is calculated using an implicit or explicit form

    Default:True

    C++ Type:bool

    Options:

    Description:Determines whether this object is calculated using an implicit or explicit form

Advanced Parameters

  • vector_tagsnontimeThe tag for the vectors this Kernel should fill

    Default:nontime

    C++ Type:MultiMooseEnum

    Options:nontime time

    Description:The tag for the vectors this Kernel should fill

  • extra_vector_tagsThe extra tags for the vectors this Kernel should fill

    C++ Type:std::vector

    Options:

    Description:The extra tags for the vectors this Kernel should fill

  • matrix_tagssystemThe tag for the matrices this Kernel should fill

    Default:system

    C++ Type:MultiMooseEnum

    Options:nontime system

    Description:The tag for the matrices this Kernel should fill

  • extra_matrix_tagsThe extra tags for the matrices this Kernel should fill

    C++ Type:std::vector

    Options:

    Description:The extra tags for the matrices this Kernel should fill

Tagging Parameters

Input Files

Child Objects