Use a pressure BC with parallel and get a extremely large pressure value.

Hi

    I'am trying to feed west and east boundary with pressure source in a short channel
with two piers in the center. The flml mainly follows the manual "8.16 Configuring
ocean simulations",and turns on "/mesh_adaptivity/mesh_movement/free_surface/move_whole_mesh"
and "adaptive_timestep".

    It blowed up at 178 secs, and a very large pressure exists at the northwest boundary
corner near surface. The adaptive mesh is also sharp around there. But after changing
nproc from 2 to 1 and running again. It performs very well. In another case with parallel
doesn't get this problem.

  Does it mean running in parallel may take risk with some meshs?

BC:
West/East: Pressure Source (use dirichlet read from file)
South/North side: no normal flow
Bottom: no normal flow and drag
Top: free surface
Pier:no slip

terrain:
Thannel:length 55m, width 45m and depth 5m (2 sigma layer)
pier: radius 2.1m

The geo and flml contents are below.

#------------ pier_tsu.geo ------------

// center coordinate
xc=0; yc=0; // model center
xp1=xc-6.6; yp1=yc; // south pier center 6.6
xp2=xc+6.6; yp2=yc; // north pier center 6.6
rad = 2.1; // pier radius rad = 2.1
d1w=5; // resolution at boumdary 50
d1e=5;
d2=2.5; // 5
d3=1; // resolution at pier
// boundary
wlen=27.5; //27.5
elen=27.5; //27.5
wid=45;
// 2345
// 1876
Point(1) = {xc-1*wlen, yc-0.5*wid, 0, d1w}; //sw
Point(2) = {xc-1*wlen, yc+0.5*wid, 0, d1w}; //nw
Point(3) = {xc-0.8*wlen, yc+0.5*wid, 0, d2};//nnw
Point(4) = {xc+0.8*elen, yc+0.5*wid, 0, d2};//nne
Point(5) = {xc+1*elen, yc+0.5*wid, 0, d1e}; //ne
Point(6) = {xc+1*elen, yc-0.5*wid, 0, d1e}; //sw
Point(7) = {xc+0.8*elen, yc-0.5*wid, 0, d2};//ssw
Point(8) = {xc-0.8*wlen, yc-0.5*wid, 0, d2};//sse

Line(1) = {1, 2};
Line(2) = {2, 3};
Line(3) = {3, 4};
Line(4) = {4, 5};
Line(5) = {5, 6};
Line(6) = {6, 7};
Line(7) = {7, 8};
Line(8) = {8, 1};

// WEST PIER
Point(9) = {xp1, yp1, 0, d3};
Point(10) = {xp1-rad, yp1, 0, d3};
Point(11) = {xp1+rad, yp1, 0, d3};
Circle(9) = {10, 9, 11};
Circle(10) = {11, 9, 10};

// EAST PIER
Point(12) = {xp2, yp2, 0, d3};
Point(13) = {xp2-rad, yp2, 0, d3};
Point(14) = {xp2+rad, yp2, 0, d3};
Circle(11) = {13, 12, 14};
Circle(12) = {14, 12, 13};

Line Loop(11) = {1,2,3,4,5,6,7,8}; //BOUNDARY
Line Loop(12) = {9,10}; // SOUTH PIER
Line Loop(13) = {11,12}; // NORTH PIER

Plane Surface(14) = {11,12,13};

Physical Line(1) = {1}; //E
Physical Line(2) = {2,3,4}; //N
Physical Line(3) = {5}; //W
Physical Line(4) = {6,7,8}; //S
Physical Line(5) = {9,10,11,12}; // WEST EAST PIERS
Physical Surface(6) = {14};

#--------- pier_tsu.flml ---------
<?xml version='1.0' encoding='utf-8'?>
<fluidity_options>
  <simulation_name>
    <string_value lines="1">pier_tsu</string_value>
  </simulation_name>
  <problem_type>
    <string_value lines="1">fluids</string_value>
  </problem_type>
  <geometry>
    <dimension>
      <integer_value rank="0">3</integer_value>
    </dimension>
    <mesh name="CoordinateMesh">
      <from_mesh>
        <mesh name="InputMesh"/>
        <extrude>
          <regions name="WholeMesh">
            <bottom_depth>
              <constant>
                <real_value rank="0">5</real_value>
              </constant>
            </bottom_depth>
            <sizing_function>
              <sigma_layers>
                <standard>
                  <integer_value rank="0">2</integer_value>
                </standard>
              </sigma_layers>
            </sizing_function>
            <top_surface_id>
              <integer_value rank="0">101</integer_value>
            </top_surface_id>
            <bottom_surface_id>
              <integer_value rank="0">102</integer_value>
            </bottom_surface_id>
          </regions>
        </extrude>
        <stat>
          <include_in_stat/>
        </stat>
      </from_mesh>
    </mesh>
    <mesh name="VelocityMesh">
      <from_mesh>
        <mesh name="CoordinateMesh"/>
        <mesh_shape>
          <polynomial_degree>
            <integer_value rank="0">1</integer_value>
          </polynomial_degree>
        </mesh_shape>
        <mesh_continuity>
          <string_value>discontinuous</string_value>
        </mesh_continuity>
        <stat>
          <exclude_from_stat/>
        </stat>
      </from_mesh>
    </mesh>
    <mesh name="PressureMesh">
      <from_mesh>
        <mesh name="CoordinateMesh"/>
        <mesh_shape>
          <polynomial_degree>
            <integer_value rank="0">2</integer_value>
          </polynomial_degree>
        </mesh_shape>
        <stat>
          <exclude_from_stat/>
        </stat>
      </from_mesh>
    </mesh>
    <mesh name="InputMesh">
      <from_file file_name="pier_tsu">
        <format name="triangle"/>
        <stat>
          <exclude_from_stat/>
        </stat>
      </from_file>
    </mesh>
    <quadrature>
      <degree>
        <integer_value rank="0">8</integer_value>
        <comment>8</comment>
      </degree>
      <surface_degree>
        <integer_value rank="0">8</integer_value>
        <comment>8</comment>
      </surface_degree>
    </quadrature>
    <ocean_boundaries>
      <top_surface_ids>
        <integer_value shape="1" rank="1">101</integer_value>
      </top_surface_ids>
      <bottom_surface_ids>
        <integer_value shape="1" rank="1">102</integer_value>
      </bottom_surface_ids>
      <scalar_field name="DistanceToTop" rank="0">
        <diagnostic>
          <algorithm name="Internal" material_phase_support="multiple"/>
          <mesh name="CoordinateMesh"/>
          <output/>
          <stat/>
          <convergence>
            <include_in_convergence/>
          </convergence>
          <detectors>
            <include_in_detectors/>
          </detectors>
          <steady_state>
            <include_in_steady_state/>
          </steady_state>
        </diagnostic>
      </scalar_field>
      <scalar_field name="DistanceToBottom" rank="0">
        <diagnostic>
          <algorithm name="Internal" material_phase_support="multiple"/>
          <mesh name="CoordinateMesh"/>
          <output>
            <exclude_from_vtu/>
          </output>
          <stat/>
          <convergence>
            <include_in_convergence/>
          </convergence>
          <detectors>
            <include_in_detectors/>
          </detectors>
          <steady_state>
            <include_in_steady_state/>
          </steady_state>
        </diagnostic>
      </scalar_field>
    </ocean_boundaries>
  </geometry>
  <io>
    <dump_format>
      <string_value>vtk</string_value>
    </dump_format>
    <dump_period>
      <constant>
        <real_value rank="0">5</real_value>
      </constant>
    </dump_period>
    <output_mesh name="VelocityMesh"/>
    <stat/>
  </io>
  <timestepping>
    <current_time>
      <real_value rank="0">0.0</real_value>
      <time_units date="seconds since 1987-01-05 00:00.0"/>
    </current_time>
    <timestep>
      <real_value rank="0">1.0</real_value>
    </timestep>
    <finish_time>
      <real_value rank="0">870.0</real_value>
    </finish_time>
    <nonlinear_iterations>
      <integer_value rank="0">3</integer_value>
      <nonlinear_iterations_at_adapt>
        <integer_value rank="0">3</integer_value>
      </nonlinear_iterations_at_adapt>
    </nonlinear_iterations>
    <adaptive_timestep>
      <requested_cfl>
        <real_value rank="0">2</real_value>
      </requested_cfl>
      <courant_number name="CFLNumber">
        <mesh name="VelocityMesh"/>
      </courant_number>
      <minimum_timestep>
        <terminate_if_reached/>
        <real_value rank="0">1e-6</real_value>
      </minimum_timestep>
      <maximum_timestep>
        <real_value rank="0">1.0</real_value>
      </maximum_timestep>
      <increase_tolerance>
        <real_value rank="0">1.1</real_value>
      </increase_tolerance>
      <at_first_timestep/>
    </adaptive_timestep>
  </timestepping>
  <physical_parameters>
    <gravity>
      <magnitude>
        <real_value rank="0">9.81</real_value>
      </magnitude>
      <vector_field name="GravityDirection" rank="1">
        <prescribed>
          <mesh name="CoordinateMesh"/>
          <value name="gravity">
            <constant>
              <real_value shape="3" dim1="dim" rank="1">0 0 -1</real_value>
            </constant>
          </value>
          <output>
            <exclude_from_vtu/>
          </output>
          <stat>
            <include_in_stat/>
          </stat>
          <detectors>
            <exclude_from_detectors/>
          </detectors>
        </prescribed>
      </vector_field>
    </gravity>
  </physical_parameters>
  <material_phase name="Fields">
    <equation_of_state>
      <fluids>
        <linear>
          <reference_density>
            <real_value rank="0">1.0</real_value>
          </reference_density>
          <subtract_out_hydrostatic_level/>
        </linear>
      </fluids>
    </equation_of_state>
    <scalar_field name="Pressure" rank="0">
      <prognostic>
        <mesh name="PressureMesh"/>
        <spatial_discretisation>
          <continuous_galerkin>
            <remove_stabilisation_term/>
            <integrate_continuity_by_parts/>
          </continuous_galerkin>
        </spatial_discretisation>
        <scheme>
          <poisson_pressure_solution>
            <string_value lines="1">only first timestep</string_value>
          </poisson_pressure_solution>
          <use_projection_method/>
          <update_discretised_equation/>
        </scheme>
        <solver>
          <iterative_method name="cg"/>
          <preconditioner name="mg">
            <vertical_lumping/>
          </preconditioner>
          <relative_error>
            <real_value rank="0">1.0e-7</real_value>
          </relative_error>
          <absolute_error>
            <real_value rank="0">0.0</real_value>
          </absolute_error>
          <max_iterations>
            <integer_value rank="0">6000</integer_value>
          </max_iterations>
          <never_ignore_solver_failures/>
          <diagnostics>
            <monitors/>
          </diagnostics>
        </solver>
        <boundary_conditions name="W_input_from_txt">
          <surface_ids>
            <integer_value shape="1" rank="1">1</integer_value>
          </surface_ids>
          <type name="dirichlet">
            <python>
              <string_value lines="20" type="code" language="python">def val(X,t):
  import inputwave_w
  g=9.81
  return inputwave_w.val(X, t)*g</string_value>
              <comment>def val(X,t):
 g=9.81
 return -0.135*g*min(1,t)</comment>
            </python>
          </type>
        </boundary_conditions>
        <boundary_conditions name="E_input_from_txt">
          <surface_ids>
            <integer_value shape="1" rank="1">3</integer_value>
          </surface_ids>
          <type name="dirichlet">
            <python>
              <string_value lines="20" type="code" language="python">def val(X,t):
  import inputwave_e
  g=9.81
  return inputwave_e.val(X, t)*g</string_value>
              <comment>def val(X,t):
 g=9.81
 return -0.135*g*min(1,t)</comment>
            </python>
          </type>
        </boundary_conditions>
        <output/>
        <stat/>
        <convergence>
          <include_in_convergence/>
        </convergence>
        <detectors>
          <exclude_from_detectors/>
        </detectors>
        <steady_state>
          <exclude_from_steady_state/>
        </steady_state>
        <consistent_interpolation/>
      </prognostic>
    </scalar_field>
    <scalar_field name="Density" rank="0">
      <diagnostic>
        <algorithm name="Internal" material_phase_support="multiple"/>
        <mesh name="VelocityMesh"/>
        <output/>
        <stat/>
        <convergence>
          <include_in_convergence/>
        </convergence>
        <detectors>
          <include_in_detectors/>
        </detectors>
        <steady_state>
          <include_in_steady_state/>
        </steady_state>
      </diagnostic>
    </scalar_field>
    <vector_field name="Velocity" rank="1">
      <prognostic>
        <mesh name="VelocityMesh"/>
        <equation name="Boussinesq"/>
        <spatial_discretisation>
          <discontinuous_galerkin>
            <viscosity_scheme>
              <compact_discontinuous_galerkin/>
              <tensor_form/>
            </viscosity_scheme>
            <advection_scheme>
              <upwind/>
              <project_velocity_to_continuous>
                <mesh name="CoordinateMesh"/>
              </project_velocity_to_continuous>
              <integrate_advection_by_parts>
                <twice/>
              </integrate_advection_by_parts>
            </advection_scheme>
          </discontinuous_galerkin>
          <conservative_advection>
            <real_value rank="0">0.0</real_value>
          </conservative_advection>
        </spatial_discretisation>
        <temporal_discretisation>
          <theta>
            <real_value rank="0">1</real_value>
          </theta>
          <relaxation>
            <real_value rank="0">1</real_value>
          </relaxation>
          <discontinuous_galerkin>
            <maximum_courant_number_per_subcycle>
              <real_value rank="0">0.1</real_value>
            </maximum_courant_number_per_subcycle>
          </discontinuous_galerkin>
        </temporal_discretisation>
        <solver>
          <iterative_method name="gmres">
            <restart>
              <integer_value rank="0">45</integer_value>
            </restart>
          </iterative_method>
          <preconditioner name="sor"/>
          <relative_error>
            <real_value rank="0">1.0e-7</real_value>
          </relative_error>
          <absolute_error>
            <real_value rank="0">0</real_value>
          </absolute_error>
          <max_iterations>
            <integer_value rank="0">10000</integer_value>
          </max_iterations>
          <never_ignore_solver_failures/>
          <diagnostics>
            <monitors/>
          </diagnostics>
        </solver>
        <initial_condition name="WholeMesh">
          <constant>
            <real_value shape="3" dim1="dim" rank="1">0.0 0.0 0.0</real_value>
          </constant>
        </initial_condition>
        <boundary_conditions name="T_FreeSurface">
          <surface_ids>
            <integer_value shape="1" rank="1">101</integer_value>
          </surface_ids>
          <type name="free_surface"/>
        </boundary_conditions>
        <boundary_conditions name="N_S_B_NoNormalFlow">
          <surface_ids>
            <integer_value shape="3" rank="1">2 4 102</integer_value>
          </surface_ids>
          <type name="no_normal_flow"/>
        </boundary_conditions>
        <boundary_conditions name="P_NoSlip">
          <surface_ids>
            <integer_value shape="1" rank="1">5</integer_value>
          </surface_ids>
          <type name="dirichlet">
            <align_bc_with_cartesian>
              <x_component>
                <constant>
                  <real_value rank="0">0</real_value>
                </constant>
              </x_component>
              <y_component>
                <constant>
                  <real_value rank="0">0</real_value>
                </constant>
              </y_component>
              <z_component>
                <constant>
                  <real_value rank="0">0</real_value>
                </constant>
              </z_component>
            </align_bc_with_cartesian>
          </type>
        </boundary_conditions>
        <boundary_conditions name="B_Drag">
          <surface_ids>
            <integer_value shape="1" rank="1">102</integer_value>
          </surface_ids>
          <type name="drag">
            <constant>
              <real_value rank="0">2.5e-3</real_value>
            </constant>
            <quadratic_drag/>
          </type>
        </boundary_conditions>
        <tensor_field name="Viscosity" rank="2">
          <prescribed>
            <value name="WholeMesh">
              <isotropic>
                <constant>
                  <real_value rank="0">1e-6</real_value>
                </constant>
              </isotropic>
            </value>
            <output/>
          </prescribed>
        </tensor_field>
        <vertical_stabilization>
          <implicit_buoyancy/>
        </vertical_stabilization>
        <output/>
        <stat>
          <include_in_stat/>
          <previous_time_step>
            <exclude_from_stat/>
          </previous_time_step>
          <nonlinear_field>
            <exclude_from_stat/>
          </nonlinear_field>
        </stat>
        <convergence>
          <include_in_convergence/>
        </convergence>
        <detectors>
          <include_in_detectors/>
        </detectors>
        <steady_state>
          <include_in_steady_state/>
        </steady_state>
        <consistent_interpolation/>
      </prognostic>
    </vector_field>
    <scalar_field name="FreeSurface" rank="0">
      <diagnostic>
        <algorithm name="Internal" material_phase_support="multiple"/>
        <mesh name="PressureMesh"/>
        <output/>
        <stat/>
        <convergence>
          <include_in_convergence/>
        </convergence>
        <detectors>
          <include_in_detectors/>
        </detectors>
        <steady_state>
          <exclude_from_steady_state/>
        </steady_state>
      </diagnostic>
    </scalar_field>
    <scalar_field name="DG_CourantNumber" rank="0">
      <diagnostic>
        <algorithm name="Internal" material_phase_support="multiple"/>
        <mesh name="VelocityMesh"/>
        <output/>
        <stat/>
        <convergence>
          <include_in_convergence/>
        </convergence>
        <detectors>
          <include_in_detectors/>
        </detectors>
        <steady_state>
          <include_in_steady_state/>
        </steady_state>
      </diagnostic>
    </scalar_field>
    <vector_field name="BedShearStress" rank="1">
      <diagnostic>
        <algorithm name="Internal" material_phase_support="multiple"/>
        <mesh name="VelocityMesh"/>
        <density>
          <real_value rank="0">1000</real_value>
        </density>
        <calculation_method>
          <drag_coefficient>
            <real_value rank="0">2.5e-3</real_value>
          </drag_coefficient>
        </calculation_method>
        <output/>
        <stat>
          <include_in_stat/>
        </stat>
        <detectors>
          <include_in_detectors/>
        </detectors>
      </diagnostic>
    </vector_field>
  </material_phase>
  <mesh_adaptivity>
    <mesh_movement>
      <free_surface>
        <move_whole_mesh/>
      </free_surface>
      <vector_field name="GridVelocity" rank="1">
        <diagnostic>
          <algorithm name="Internal" material_phase_support="multiple"/>
          <mesh name="CoordinateMesh"/>
          <output/>
          <stat>
            <include_in_stat/>
          </stat>
          <convergence>
            <include_in_convergence/>
          </convergence>
          <detectors>
            <include_in_detectors/>
          </detectors>
          <steady_state>
            <include_in_steady_state/>
          </steady_state>
        </diagnostic>
      </vector_field>
    </mesh_movement>
  </mesh_adaptivity>
</fluidity_options>