BEM acoustics of a tunnel model

A simplified tunnel model is subjected to a user defined velocity excitation. *FREQUENCY_DOMAIN_ACOUSTIC_BEM_PANEL_CONTRIBUTION is used for running acoustic panel contribution analysis with variational indirect BEM. Example 8.6 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

*DEFINE_CURVE
*ELEMENT_SHELL
*END
*FREQUENCY_DOMAIN_ACOUSTIC_BEM_PANEL_CONTRIBUTION
*KEYWORD  
*MAT_RIGID
*NODE
*PART
*SECTION_SHELL
*SET_NODE_LIST
*SET_SEGMENT
*TITLE

*KEYWORD  
*TITLE
A tunnel model                                                                  
*FREQUENCY_DOMAIN_ACOUSTIC_BEM_PANEL_CONTRIBUTION
  1.210000 343.00000 150.00000 300.00000       201  0.005000     0.000 2.0000E-5
         1         1         0         0         0         0         0         0
         2      2000 1.0000E-6         8     0.000     0.000         0         0
                   4 
         1         2         0         3         3
         2         2         0         3         3
         3         2         0         3         3
         4         2         0         3         3
         1
*PART
tunnel                                                                          
         1         1         1         0         0         0         0         0
*SECTION_SHELL
         1         0     0.000         0         0         0         0         0
  0.001000  0.001000  0.001000  0.001000     0.000     0.000     0.000         0
*MAT_RIGID
         1  0.100000  0.300000     0.000     0.000     0.000     0.000          
  1.000000         7         7
     0.000     0.000     0.000     0.000     0.000     0.000
*DEFINE_CURVE
         3         0     0.000  0.010000     0.000     0.000         0
           1.0000000           1.0000000
        10000.000000           1.0000000
*SET_NODE_LIST
         1     0.000     0.000     0.000     0.000          
      5401         0         0         0         0         0         0         0
*SET_SEGMENT
*ELEMENT_SHELL
*NODE
*END