problem: !SequentialCoupling
  description: '[u''test18:'', u''diffusion'', u''through'', u''fractures'']'
  mesh:
    mesh_file: ./input/test18.msh
    regions:
      - name: center
        id: 30
        element_list:
          - 45
  primary_equation: !Steady_MH
    input_fields:
      - r_set: BOUNDARY
        bc_type: dirichlet
        bc_pressure: 0
      - rid: 20
        cross_section: 0.01
      - rid: 24
        cross_section: 1
    output:
      output_stream: 
        file: ./test18.pvd
        format: !vtk
          variant: ascii
        name: flow_output_stream
      output_fields:
        - pressure_p0
        - pressure_p1
        - velocity_p0
    balance: true
    solver: !Petsc
      a_tol: 1.0e-12
      r_tol: 1.0e-12
  secondary_equation: !SoluteTransport_DG
    input_fields:
      - r_set: BOUNDARY
        bc_conc: 0
      - rid: 20
        init_conc: 0
        diff_m: 0.1
      - rid: 24
        init_conc: 0
        diff_m: 0.1
        dg_penalty: 100
      - rid: 30
        init_conc: 1
    output_stream: 
      file: ./transport-implicit.pvd
      format: !vtk
        variant: ascii
      time_step: 0.001
      name: transport_output_stream
    substances:
      - A
    solver: !Petsc
      a_tol: 1.0e-12
      r_tol: 1.0e-12
    time:
      end_time: 0.01
      max_dt: 0.001
    balance:
      cumulative: true