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Wind and Structures
  Volume 30, Number 5, May 2020, pages 485-497
DOI: http://dx.doi.org/10.12989/was.2020.30.5.485
 


Hydrodynamic forces on blocks and vertical wall on a step bottom
Ramnarayan Mondal and Md. Mahbub Alam

 
Abstract
    A study, using potential water wave theory, is conducted on the oblique water wave motion over two fixed submerged rectangular blocks (breakwaters) placed over a finite step bottom. We have considered infinite and semi-infinite fluid domains. In both domains, the Fourier expansion method is employed to obtain the velocity potentials explicitly in terms of the infinite Fourier series. The unknown coefficients appearing in the velocity potentials are determined by the eigenfunction expansion matching method at the interfaces. The derived velocity potentials are used to compute the hydrodynamic horizontal and vertical forces acting on the submerged blocks for different values of block thickness, gap spacing between the two blocks, and submergence depth of the upper block from the mean free surface. In addition, the wave load on the vertical wall is computed in the case of the semi-infinite fluid domain for different values of blocks width and the incident wave angle. It is observed that the amplitudes of hydrodynamic forces are negligible for larger values of the wavenumber. Furthermore, the upper block experiences a higher hydrodynamic force than the lower block, regardless of the gap spacing, submergence depth, and block thickness.
 
Key Words
    submerged breakwaters; uneven bottom; semi-infinite fluid domain
 
Address
Ramnarayan Mondal: Institute for Turbulence-Noise-Vibration Interaction and Control Harbin Institute of Technology, Shenzhen 518055, China
Md. Mahbub Alam: Digital Engineering Laboratory of Offshore Equipment, Shenzhen, China
 

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