"Water channel test"
13 2 1 8 2 3 1 0  ! M NE NG N NSPACE NPROP NMAT NFORCE
    1    1      5.        15.          0  ! wall v=0
    2    1      5.        17.5         0  ! wall v=0
    3    1      5.        20.          0  ! wall v=0
    4    1      30.       7.           0  ! wall v=0
    5    0      30.       20.          0  ! no bc
    6    1      55.       0.           0  ! wall v=0
    7    0      55.       10.          0  ! no bc
    8    0      55.       20.          0  ! no bc
    9    1      80.       7.           0  ! wall v=0
   10    0      80.       20.          0  ! no bc
   11    1      105.      13.          0  ! wall v=0
   12    1      105.      16.5         0  ! wall v=0
   13    1      105.      20.          0  ! wall v=0
    1    1    1    6    8    3    4    7    5    2             ! el 1
    2    1    6   11   13    8    9   12   10    7             ! el 2
    1        1.        1.       32.                            ! mat k k dpdx
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