BEM acoustics of a simplified compartment model

A simplified auto compartment model is analysed. For FFT, windowing technique raised cosine is used. Differences between collocation BEM and variational indirect BEM can be studied. Example 8.7 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.

*CONTROL_TERMINATION
*CONTROL_TIMESTEP
*DATABASE_BINARY_D3DUMP
*DATABASE_BINARY_D3PLOT
*DATABASE_BINARY_D3THDT
*DATABASE_BINARY_RUNRSF
*DATABASE_FREQUENCY_BINARY_D3ACS
*DEFINE_CURVE
*ELEMENT_SHELL
*ELEMENT_SOLID
*END
*FREQUENCY_DOMAIN_ACOUSTIC_BEM
*KEYWORD  
*MAT_ELASTIC_FLUID
*MAT_RIGID
*NODE
*PART
*SECTION_SHELL
*SECTION_SOLID
*SET_NODE
*SET_SEGMENT
*TITLE

*KEYWORD
*TITLE
Acoustic analysis of a simplified compartment model by BEM
*FREQUENCY_DOMAIN_ACOUSTIC_BEM
1.2300E-12 3.4000E+5  10.00000 500.00000       491         0     0.0002.0000E-11
         0         0       200         1         4
         3      1000 1.0000E-6         8
                   2 
         1         2         0        -3
         2         2         0        -2
*DATABASE_FREQUENCY_BINARY_D3ACS
         1
*CONTROL_TERMINATION
  0.187970         0     0.000     0.000 50.000000
*CONTROL_TIMESTEP
     0.000  0.800000
     0.000         0         0
*DATABASE_BINARY_D3DUMP
 10000.000
*DATABASE_BINARY_D3PLOT
  0.001000
         0
*DATABASE_BINARY_D3THDT
 5.0000E-4
*DATABASE_BINARY_RUNRSF
 5000.0000
*PART
body = Al 3mm thick 
         1         1         1
*SECTION_SHELL
         1         2
  3.000000  3.000000  3.000000  3.000000
*MAT_RIGID
         1 2.7000E-9 72000.000  0.300000     0.000     0.000     0.000          
  1.000000         7         7
     0.000     0.000     0.000     0.000     0.000     0.000
*PART
acoustic medium                                                                 
         3         3         3
*SECTION_SOLID
         3         2
*MAT_ELASTIC_FLUID
         3  1.220000     0.000     0.000     0.000     0.000 141.03000
     0.000     0.000
*ELEMENT_SOLID
*ELEMENT_SHELL
*NODE
*SET_NODE
       200
    110607
*DEFINE_CURVE
         2         0     0.000     0.000     0.000     0.000         0
               0.000               0.000
        1000.0000000               0.000
*DEFINE_CURVE
         3         0     0.000     0.000     0.000     0.000         0
               0.000           7.0000000
        1000.0000000           7.0000000
*SET_SEGMENT
*END