A Modified Numerical Approach for Leaky Mode Computation

Acoustic modelling using normal mode approach is examined in Indian Ocean environment with a soft sediment bottom. Computing leaky modes is critical in modelling the acoustic field in these environments. Normal mode programs KRAKEN and KRAKENC are applied to these environments and their instability in determining some of the leaky modes is pointed out. Rayleigh quotient iteration is proposed in place of inverse iteration in KRAKENC for determining the dominant complex modes. This approach provides better estimate of all the dominant modes and is found to be stable even at higher frequencies.