Solution
  # Transient solution from time 0 to 5 over 500 time steps
  transient
  time_step 1.0e-2
  nsteps 500
End

File
  geometry_file 'infinite_100elem.exo'
End

Linesample
  #This is an output capability, outputting nodal values at the
  #specified points, which might not exactly line up to mesh
  #points.
  samples per line 2
  endpoint 0 0 500 0 0 500.001
  format exodus
End

Outputs
  # Acoustic pressure
  apressure
End

Echo
  # Turn off the echoing of the input deck to the output log file.
  # Might be useful if the input deck is very long
  input off
End

Boundary
  # Infinite BC is an absorbing boundary condition where
  # waves exit the domain without reflection.  Additional
  # parameters to drive this BC set in 'block 111'
  sideset 1
    infinite_element
    use block 111
End

Block 1
  material "air"
End

Block 111
  # Additional information to define non-reflecting boundary conditions
  # on the acoustic domain
  infinite_element
    radial_poly legendre
    order 3
    neglect_mass yes
    ellipsoid_dimensions 200 200 200
End

Material "air"
  # This is the acoustic 'air' material
  density 1.293
  acoustic
  c0 332.0
End

Function 3
  type analytic
  evaluate expression = "sin(2 * pi * t)"
End

Loads
  # Define an acoustic acceleration on exterior of the body.
  # This is equivalent to a 'force' in a structural problem
  sideset 2
    acoustic_accel -1.0
    function 3
End

GDSW
  # Significantly tighter solver tolerance than default 
  solver_tol 1.0e-9
End