As an example of the use of OASP for computing transmission losses, and for demonstrating the difference between the full Bessel function integration and the default fast-field Hankel function approximation, the following data files computes the transfer function for a 150 Hz simple point source in a lossless, infinite fluid medium.
free.dat | free_f.dat _____________________________________________________________________ Infinite medium. | Inf. medium. OASP Bes.Int. N J | N J f 150 0 | 150 0 2 | 2 0 1500 0 0.1 0 1 0 | 0 1500 0 0.1 0 1 0 0 1500 0 0.1 0 1 0 | 0 1500 0 0.1 0 1 0 0 | 0 -200 200 61 30 | -200 200 61 30 1000 1E8 | 1000 1E8 -1 1 1 1 | -1 1 1 1 1024 150 150 0.0005 0 0.005 81 | 1024 150 150 0.0005 0 0.005 81
The execution of OASP with these input files generates the transfer function files, which are then converted to transmission loss by PP. Figure4 shows the transmission loss contours in depth and range, plotted from PP using plotmtv. The near field differences between the 'exact' and the fast-field Hankel transforms are evident.