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Boundary conditions

User defined boundary conditions

This subroutine is used for user-defined boundary values, characterized by the parameter *UBoundary command in the input file. The header and variable description is given in the following. Notice that numgeo searches for the file user_boundary_conditions.so in the current working directory.

Linux

subroutine user_boundary_conditions(dof,inode,istep,time,coords,bc_value)&
             bind(c,name='user_boundary_conditions')
  use, intrinsic :: iso_c_binding
  implicit none
  character(c_char)           , intent(in)    :: dof      
  integer(c_int)              , intent(in)    :: inode   
  integer(c_int)              , intent(in)    :: istep    
  real(c_double)              , intent(in)    :: time      
  real(c_double), dimension(3), intent(in)    :: coords    
  real(c_double), dimension(3), intent(inout) :: bc_value

  ... user coding

end subroutine user_boundary_conditions

Windows

subroutine user_boundary_conditions(dof,inode,istep,time,coords,bc_value) 
  implicit none
  !DEC$ ATTRIBUTES DLLEXPORT, STDCALL, REFERENCE :: user_boundary_conditions
  character            , intent(in)    :: dof      
  integer              , intent(in)    :: inode   
  integer              , intent(in)    :: istep    
  real(8)              , intent(in)    :: time      
  real(8), dimension(3), intent(in)    :: coords    
  real(8), dimension(3), intent(inout) :: bc_value

  ... user coding

end subroutine user_boundary_conditions

  • dof: Degree of freedom to assign the boundary condition to, e.g. u1 for the displacement in horizontal direction, or pw for the pore water pressure

  • inode: Node label (id)

  • istep: Step number

  • time: Step time

  • coords(:): Coordinates of the current node

  • bc_value(:): Total value of the prescribed variable at this point. The variable may be displacement, pore water pressure, etc., depending on the degree of freedom constrained. bc_value(1) will be passed into the routine as the value defined by any magnitude and/or amplitude specification for the boundary condition or connector motion. If the analysis procedure requires that the time derivatives of prescribed variables be defined (for example, in a dynamic analysis the velocity and acceleration, as well as the value of the variable, are needed), must be given in bc_value(2) and in bc_value(3).