The bottom parameters of Model 1 are: bottom speed 1680m/s, bottom 1.8g/cm3 and bottom absorption 0.015. The transmission losses calculated by Kraken and BDRM are shown in Fig. 7(b), where the source and receiver are both at 50m, and the frequency is 500Hz. For Model 1, the results by BDRM and Kraken agree with each other well.
Fig. 7 TLS calculated by BDRM and Kraken codes for bottom model 1. (a) Speed profile, (b) TL vs range for source and receiver depths at 50m, frequency of 500Hz.
The bottom parameters of Model 2 are bottom speed 1540m/s, bottom density of 1.6g/cm3, bottom absorption of 0.01. The source and receiver are both at 7m and the frequency is 2000Hz. The transmission losses calculated by BDRM. Kraken, Krakenc and FEPE codes are show in Fig. 8, and for Model 2 the results of FEPE (γ/32) and BDRM agree with each other well, while the result by Kraken has a large deviation. This phenomenon can be explained as that the traditional disturbance method will not be suited to Model 2 because the bottom sound speed of this example is near the phase speed of effective modes, which make main contribution to the sound field.
