( Ground flow.
  Two-dimensional.
  Only permeability.
  Lower nodes prescribed pressure 1.
  Upper nodes prescribed pressure 0.
  Middle node should get pressure 0.5. )

echo -no
number_of_space_dimensions 2
groundflow_velocity
groundflow_pressure
end_initia

node 1  0 0
node 2  1 0
node 3  0 1
node 4  1 1
node 5  0 2
node 6  1 2
element 1  -quad4 1 2 3 4
element 2  -quad4 3 4 5 6 

bounda_unknown 0  -ra 1 2 -ra -pres
bounda_time    0  0.0 0.0 1. 1. 100. 1.
bounda_unknown 1  -ra 5 6 -ra -pres
bounda_time    1  0.0 0.0 100.0 0.

group_type 0  -groundflow
group_groundflow_permeability 0  0.1 0.1

print_filter 0  -node_dof -all -pres

control_timestep  0  1. 1.
(control_print     0  -time_current -node_dof)

target_item 0   -node_dof 3 -pres
target_value   0   0.5 1.e-4
end_data
