In the present work, we focus on noise generation by a flapping foil used for small ship and AUV propulsion and its propagation in the inhomogeneous sea environment. The pressure field and the forces produced by flapping thruster motion, obtained by a BEM model, are used to calculate the dipole and monopole terms associated with the initial – boundary value problem governed by the wave equation. Initially, an acoustic model in free space based on the Farassat formulation is derived. Subsequently, the latter is extended to account for a bounded domain and an inhomogeneous medium. For simplicity, the 2D sea acoustic waveguide is considered, and the presented numerical method is based on a Finite Difference scheme (FDM), incorporating free-surface and seabed effects as well as a variable sound speed profile. Moreover, the numerical scheme is supplemented by a perfectly matched layer (PML) for the treatment of the outgoing radiating field behavior in the open boundaries. Numerical results are presented for the verification of the present method in the case of time-harmonic sources. Future extensions are discussed regarding the application of a Finite Element Method (FEM) – PML scheme to treat localized scatterers and curved boundaries as well as 3D effects.
|Title of host publication||Ocean Engineering; Honoring Symposium for Professor Gunther F. Clauss on Hydrodynamics and Ocean Engineering|
|Publisher||American Society of Mechanical Engineers(ASME)|
|Number of pages||8|
|Publication status||E-pub ahead of print - 13 Oct 2022|
|Event||ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2022 - Hamburg, Germany|
Duration: 5 Jun 2022 → 10 Jun 2022
|Name||Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE|
|Conference||ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2022|
|Period||5/06/22 → 10/06/22|
Bibliographical noteFunding Information:
The present work has been supported by Seatech H2020 project received funding from the European Union’s Horizon 2020 research and innovation program under the grant agreement No 857840. The opinions expressed in this document reflect only the author’s view and in no way reflect the European Commission’s opinions. The European Commission is not responsible for any use that may be made of the information it contains.
- FDM-PML model
- flapping thruster
- noise propagation
- sea environment