Results

The distribution of normalized sound pressure level in the YZ-plane (ϕ = 90° in the spherical coordinate system) is calculated at distance r = 100 m from the origin of the coordinate system for 0° to 90°, or from θ = 90° to 0° in the spherical coordinate system. The sound pressure is normalized with respect to the sound pressure at r = 100 and θ = 90°. The normalized sound pressure levels obtained for k =1 and k = 2 are compared to the NADwork Version 3.2 results given in the NAFEMS article.

A numerical reference solution can be found in A.F. Seybert, B. Soenarko, F.J. Rizzo, and D.J. Shippy, “An advanced computational method for radiation and scattering of acoustic waves in three dimensions”, J. Acous. Soc. Am., 77(2), 1985.

 -------------- Pn (k = 1) ---------------
 |  THETA  |  Mechanical APDL  |  RATIO  |
  
      0          0.772           1.003  
      10         0.782           1.002  
      20         0.807           1.009  
      30         0.844           1.004  
      40         0.884           1.005  
      50         0.923           1.003  
      60         0.955           1.006  
      70         0.980           0.990  
      80         0.995           0.995  
      90         1.000           1.000  

 -------------- Pn (k = 2) ---------------
 |  THETA  |  Mechanical APDL  |  RATIO  |
  
      0          0.468            1.018  
      10         0.424            1.033  
      20         0.293            1.009  
      30         0.099            0.989  
      40         0.163            1.019  
      50         0.389            0.997  
      60         0.592            0.987  
      70         0.780            0.987  
      80         0.935            1.006  
      90         0.999            0.999