# Boundary Conditions

JuAFEM.DirichletType
Dirichlet(u, ∂Ω, f)
Dirichlet(u, ∂Ω, f, component)

Create a Dirichlet boundary condition on u on the ∂Ω part of the boundary. f is a function that takes two arguments, x and t where x is the spatial coordinate and t is the current time, and returns the prescribed value. For example, here we create a Dirichlet condition for the :u field, on the faceset called ∂Ω and the value given by the sin function:

dbc = Dirichlet(:u, ∂Ω, (x, t) -> sin(t))

If :u is a vector field we can specify which component the condition should be applied to by specifying component. component can be given either as an integer, or as a vector, for example:

dbc = Dirichlet(:u, ∂Ω, (x, t) -> sin(t), 1)      # applied to component 1
dbc = Dirichlet(:u, ∂Ω, (x, t) -> sin(t), [1, 3]) # applied to component 1 and 3

Dirichlet boundary conditions are added to a ConstraintHandler which applies the condition via apply!.

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JuAFEM.add!Function
add!(ch::ConstraintHandler, dbc::Dirichlet)

Add a Dirichlet boundary condition to the ConstraintHandler.

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JuAFEM.close!Function
close!(dh::MixedDofHandler)

Closes the dofhandler and creates degrees of freedom for each cell. Dofs are created in the following order: Go through each FieldHandler in the order they were added. For each field in the FieldHandler, create dofs for the cell. This means that dofs on a particular cell will be numbered according to the fields; first dofs for field 1, then field 2, etc.

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close!(ch::ConstraintHandler)

Close and finalize the ConstraintHandler.

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