  Getting inspired from swimming natural species, a lot of research is being
carried out in the field of unmanned underwater vehicles. During the last two
decades, more emphasis on the associated hydrodynamic mechanisms, structural
dynamics, control techniques and, its motion and path planning has been
prominently witnessed in the literature. Considering the importance of the
involved acoustic mechanisms, we focus on the quantification of flow noise
produced by an oscillating hydrofoil here employed as a kinematic model for
fish or its relevant appendages. In our current study, we perform numerical
simulations for flow over an oscillating hydrofoil for a wide range of flow and
kinematic parameters. Using the Ffowcs-Williams and Hawkings (FW-H) method, we
quantify the flow noise produced by a fish during its swimming for a range of
kinematic and flow parameters including Reynolds number, reduced frequency, and
Strouhal number. We find that the distributions of the sound pressure levels at
the oscillating frequency and its first even harmonic due to the pressure
fluctuations in the fluid domain are dipole-like patterns. The magnitudes of
these sound pressure levels depend on the Reynolds number and Strouhal number,
whereas the direction of their dipole-axes appears to be affected by the
reduced frequency only. Moreover, We also correlate this emission of sound
radiations with the hydrodynamic force coefficients.
