Xu, Qilin (2017-05). Wave Interactions with Arrays of Vertical Bottom-Mounted Deformable Cylinders. Master's Thesis. Thesis uri icon

abstract

  • This thesis describes research regarding the trapping of water waves through hydroelastic interaction with bottom-mounted cylinder arrays in shallow water. A modal decomposition and superposition approach has been applied to the calculation of the hydro-elastic response of arrays of deformable cylinders exposed to incident long waves. The cylinder array is considered as an effective medium, and the theory associated with the Fabry-P?rot Interferometer is applied. Therefore, the refraction index within the array and the transmittance and reflectance by the array can be determined. Equations of motion for a single deformable cylinder are derived from the theory of vibration for thin shells, and added mass, radiation damping and stiffness matrices are defined. Analytical solutions for the response of a single deformable cylinder are calculated and compared with the numerical results from WAMIT. The results show a good agreement. Transmission and reflection coefficients for rigid cylinder arrays have been calculated based on effective medium theory and found to match those determined from WAMIT. The final step of the research involves investigating the hydro-elastic response of deformable cylinder arrays exposed to incident waves. Wave interactions of arrays of elastic cylinders that can expand and contract radially are simulated using WAMIT, and the associated wave fields within and outside the array are analyzed and discussed. The main objective of this research is to investigate whether significant "wave trapping" can occur when waves encounter elastic cylinders arranged in periodic or random arrays. If the insertion loss calculated in the case of flexible cylinder arrays is significant, one may conclude that in shallow water those arrays could attenuate incident long waves of certain frequencies. The research is motivated by analogous theories of wave trapping that can occur when acoustic waves encounter bubbly media, such as breaking water waves. Furthermore, such arrangement of pulsating cylinders may lead to novel ways of extracting wave energy through hydro-mechanical coupling with suitable devices.
  • This thesis describes research regarding the trapping of water waves through hydroelastic interaction with bottom-mounted cylinder arrays in shallow water. A modal decomposition and superposition approach has been applied to the calculation of the hydro-elastic response of arrays of deformable cylinders exposed to incident long waves. The cylinder array is considered as an effective medium, and the theory associated with the Fabry-P?rot Interferometer is applied. Therefore, the refraction index within the array and the transmittance and reflectance by the array can be determined. Equations of motion for a single deformable cylinder are derived from the theory of vibration for thin shells, and added mass, radiation damping and stiffness matrices are defined. Analytical solutions for the response of a single deformable cylinder are calculated and compared with the numerical results from WAMIT. The results show a good agreement. Transmission and reflection coefficients for rigid cylinder arrays have been calculated based on effective medium theory and found to match those determined from WAMIT. The final step of the research involves investigating the hydro-elastic response of deformable cylinder arrays exposed to incident waves. Wave interactions of arrays of elastic cylinders that can expand and contract radially are simulated using WAMIT, and the associated wave fields within and outside the array are analyzed and discussed.

    The main objective of this research is to investigate whether significant "wave trapping" can occur when waves encounter elastic cylinders arranged in periodic or random arrays. If the insertion loss calculated in the case of flexible cylinder arrays is significant, one may conclude that in shallow water those arrays could attenuate incident long waves of certain frequencies. The research is motivated by analogous theories of wave trapping that can occur when acoustic waves encounter bubbly media, such as breaking water waves. Furthermore, such arrangement of pulsating cylinders may lead to novel ways of extracting wave energy through hydro-mechanical coupling with suitable devices.

publication date

  • May 2017