[bcs] block

The block [bcs] is used to apply the different types of boundary conditions, i.e. Dirichlet boundary condition, Neumann boundary condition, Robin boundary condition, as well as User-Defined-BC (UBC). This block's layout looks as follows:

[bcs]
  [mybc1]
    type=dirichlet
    dofs=dof1
    boundary=left right ...
    value=bcvalue
  [end]
[end]

options

The type = option specifies the name of the boundary condition type one wants to use.

dofs= specifies which DoF we want to use. It should be noted that, more than one DoF can be accepted, for instance, dofs=ux uy.

boundary= specifies the name of the boundary, which we want to apply the related boundary condition. The name of the boundary should be defined in your mesh file. For the built-in mesh, we use left and right for the point/line/surface at xmin and xmax. Similarly, bottom and top are used for the line/surface at ymin and ymax. Then back and front are used for the surface at zmin and zmax.

value= specifies the boundary value we want to use. It should be a single value, instead of several numbers. If one wants to apply the time dependent boundary condition, then he can use value=t*2.0. Thus the boundary value will change overtime.

supported boundary condition type

The full list of the available boundary condition type is:

type=dirichlet
type=nodaldirichlet
type=neumann
type=nodalneumann
type=user1bc[,user2bc,user3bc,...]
type=user1dirichletbc[,user2dirichletbc,...]