Wave transformation due to barrier-rock porous structure placed on step-bottom

Venkateswarlu, V.; Karmakar, D.

doi:10.1080/17445302.2019.1694296

Cited by 18 publications

(6 citation statements)

References 25 publications

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“…The free spacing between the barrier and leeward wall a 1 / h 2 can be represented as a trapping chamber, and the interaction between the transmitted wave amplitudes from the barrier that is usually reflected back by the leeward impermeable wall, which causes the wave trapping and wave blocking. 25,34 The resonating troughs can be called as effective wave trapping points and are observed in K r which is evident in the design of the trapping chamber. The increase in d / h 1 also shows the increase in the trapping chamber length, which causes the combined effect of wave trapping and wave damping.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, the wave impact on leeward wall will be minimal in the presence of rigid bar as compared with uniform sea bottom. 25 However, the global minima is obtained in K r for all the combinations of h 2 =h 1 within 1:54d=h 1 42:5, which is evident in the design and construction of porous absorbers for better wave blocking. In the previous case ( Figure 6), structural width d=h 1 = 2 performed well in reducing K r as compared with other combinations and the global minima in K r is also observed in the same specific range of structural width within 1:54d=h 1 42:5.…”

Section: Finite-stratified Porous Absorber Without Vertical Barriermentioning

confidence: 96%

“…The study reported that the wave trapping not only depends upon barrier position but also on the porous effect parameter, 23 which plays an immense role in wave dissipation. Thereafter, porous structure placed on sloping seabed, 24 step-bottom, 25 submerged and surface piercing structure of finite width, 26 double porous barriers 27 and multiple structures away from leeward wall 28 is extensively analysed considering various incident wave and structural properties. The trapping chamber length encourages the resonating peaks and troughs in wave transformation, and resonating troughs are evident in the design of porous structure away from vertical wall to achieve maximal wave trapping.…”

Section: Introductionmentioning

confidence: 99%

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Wave motion over stratified porous absorber combined with seaward vertical barrier

Venkateswarlu

Karmakar

2020

Proceedings of the Institution of Mechanical Engineers, Part M:

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The oblique wave reflection by horizontally stratified porous absorber having two horizontal porous bars of different porosities and friction factors placed on step-type bottom is studied using eigenfunction expansion method based on linearised wave theory. The present study examines several structural configurations such as porous absorber consisting of finite and semi-infinite thickness with/without seaward vertical barrier. The present study derived the direct analytical relations to determine wave reflection by each of the structural configuration for plane-wave assumption using potential flow theory. Initially, the porous absorber considering uniform porosity and friction factor is examined and validated with available numerical results, and the direct analytical relations are also validated with available relations of possible structural configurations. In addition, the present study reported wave reflection performance of submerged single-layer and double-layer porous absorbers with/without seaward vertical barrier. The effect of bottom rigid bar, surface porous bar, middle porous bar depth, multiple porosities, friction factors, incident wave angle and porous effect parameter on wave reflection coefficient is presented in detail for various structural configurations. The significance of seaward vertical barrier on wave reflection and wave trapping is reported. The point of wave trapping, critical angle of impinging, resonating peaks and troughs due to various structural configurations are presented against structural thickness.

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Section: Resultsmentioning

confidence: 99%

Section: Finite-stratified Porous Absorber Without Vertical Barriermentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Wave motion over stratified porous absorber combined with seaward vertical barrier

Venkateswarlu

Karmakar

2020

Proceedings of the Institution of Mechanical Engineers, Part M:

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“…This is possibly due to the phase shift associated with the inertia coefficient of the porous boundary condition. 35,36 However, to understand the hydrodynamics, we have compared a numerical model having zero porosity with a model having a quadratic pressure drop and a porosity of 0.20. Table 2 reveals that the optima of scattering coefficients occur at the same relative water depth in the case of impermeable structure which varies with the porous reefs.…”

Section: Resultsmentioning

confidence: 99%

“…This is possibly due to the phase shift associated with the inertia coefficient of the porous boundary condition. 35,36 However, to understand the hydrodynamics, we have compared a numerical model having zero porosity with a model having a quadratic pressure drop and a porosity of 0.20. of zero porosity, the optima in reflection coefficient shift outward whilst there is a shift inward for a porous structure. The behaviour of the reflection coefficient is periodic whereas sub-harmonic peaks in the reflection coefficient are hardly visible when the porosity is introduced in the structure.…”

Section: Effect Of the Multiple Artificial Reef (Mar) Unitsmentioning

confidence: 99%

Gravity wave interaction with multiple submerged artificial reefs

Vijay

Neelamani

Nishad

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part M:

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In the present study, gravity wave interaction with a series of submerged artificial permeable reefs is analysed within the framework of linearised water wave theory. For wave past porous walls of the artificial reefs, a quadratic pressure drop is assumed to account for the wave energy dissipation due to the changes in wave height. The physical problem is handled for a solution using a numerical model based on the iterative multi-domain boundary element method and the developed numerical model is validated with known results in the literature. The iterative model is compared with the numerical model based on linear pressure drop boundary condition (i.e., Darcy law). The study reveals that the wave transmission reduces with the increase in the number of reef units. It is demonstrated that the transmission coefficient can be reduced to less than 0.5 when the number of reef units is greater than or equal to three for a relative height greater than 0.7, reef porosities less than 20% and for 0.4<k0h<3.0. Bragg reflection is observed when the porosity is in the range of 0 to 10% and above which the recurrent nature of wave reflection gradually fades away due to dissipation effects. The number of peaks occurring in the shallow and intermediate water depths is equal to the number of reef units wherein the maxima occur at the first frequency. A relative increase in the base width improves the energy losses but the rate of increase in energy loss decreases. The scattering coefficient pattern is oscillatory when the relative spacing between the barriers is varied and their hydrodynamic performance is invariant for higher relative base width.

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