Effect of bottom topography on wave scattering by multiple porous barriers

Kaligatla, R. B.; Tabssum, S.; Sahoo, T.

doi:10.1007/s11012-017-0790-2

Cited by 26 publications

(9 citation statements)

References 27 publications

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“…Regarding the porosity representation, most potentialflow models apply the porous pressure-drop in a linearised way and only few models use a non-linear formulation. Examples for work that use a linear relationship between pressure-drop and flow velocity are studies on a nearly vertical porous wall, done by Chakrabarti and Sahoo (1996), or for investigations on the effects of bottom topography, done by Kaligatla and Sahoo (2017) and Kaligatla et al (2018). A quadratic pressure-drop formulation has for instance been used by Mei et al (1974) in combination with shallow water theory, by Bennett et al (1992) for thin vertical barriers and by Liu and Li (2017) for an iterative boundary element model.…”

Section: Introductionmentioning

confidence: 99%

Using a porous-media approach for CFD modelling of wave interaction with thin perforated structures

Feichtner

Mackay

Tabor

et al. 2020

J. Ocean Eng. Mar. Energy

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This work presents the use of a porous-media approach for computational fluid dynamics (CFD) modelling of wave interaction with thin perforated sheets and cylinders. The perforated structures are not resolved explicitly but represented by a volumetric porous zone where a volume-averaged pressure gradient in the form of a drag term is applied to the Navier–Stokes momentum equation. The horizontal force on the structures and the free-surface elevation at wave gauges around the cylinder model have been analysed for a range of porosities and regular wave conditions. The CFD results are verified against results from a linear potential-flow model and validated against experimental results. The applied pressure gradient formulation produces good agreement for all porosity values, wave frequencies and wave steepnesses investigated. It is demonstrated that an isotropic macroscopic porosity representation used for large volumetric granular material can also be used for thin perforated structures. This approach offers greater flexibility in the range of wave conditions that can be modelled compared to approaches based on linear potential-flow theory and requires a smaller computational effort compared to CFD approaches which resolve the flow through the openings. The approach can therefore be an efficient alternative for engineering problems where large-scale effects such as global forces and the overall flow-behaviour are of the main interest.

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Section: Introductionmentioning

confidence: 99%

Using a porous-media approach for CFD modelling of wave interaction with thin perforated structures

Feichtner

Mackay

Tabor

et al. 2020

J. Ocean Eng. Mar. Energy

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“…The study suggested that the bottom standing barriers are acceptable as breakwaters, and free clamped barriers performance is significant as compared with moored clamped barriers to attenuate the maximum wave energy. Behera and Ng (2018), Kaligatla et al (2018) extended the study considering variation in the seabed characteristics in the wave reflected region. Very recently, Somervell et al (2018) proposed a simplified empirical relation to find the friction factor with known parameters like porosity, width and depth of the structure using the eigenfunction expansion method.…”

Section: Introductionmentioning

confidence: 99%

Influence of Impermeable Elevated Bottom on the Wave Scattering due to Multiple Porous Structures

Venkateswarlu¹,

Karmakar²

2020

JAFM

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The significance of multiple porous structures with finite spacing upon elevated seabed in the presence and absence of the leeward wall is examined under oblique wave impinging. Fluid propagation is assumed over the impermeable elevated bottom, and the fluid realm is separated into open water and porous structure regions. Continuity of the dynamic pressure and mass fluxes at the interfaces of the porous structure and the open water regions are adopted. The resistance and reactance due to the presence of the porous structure are taken into account using the porous structure dispersion relation. The numerical model is developed based on the eigenfunction expansion method along with matched velocity potentials at the interfaces of open water and the porous block regions. The wave reflection and transmission characteristics, energy damping and wave force impact on the leeward wall is analysed. The significance of the porosity, structural width, angle of incidence, width between the two structures and water chamber length is studied considering multiple porous blocks with finite spacing under oblique wave impinging in the presence and absence of leeward wall. The numerical results obtained in the present study agrees well with the theoretical and experimental results available in the literature. The present study illustrates that, with the increase in the number of porous blocks and gap between the porous blocks, the resonating trend is observed in the wave transformation and the influence of the elevated step height is revealed for the wave trapping.

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Section: Water Scattering By Fully Submerged Barriers Behind An Undul...mentioning

confidence: 99%

“…In addition, the horizontal length of the undulated bottom was denoted as v . In the application of EMM, the number of shelves was set to 100 M = , and no evanescent mode was considered, similar to Kaligatla, et al [47]. Sequentially, the issue of scattered water waves by J half-cosine breakwaters was considered.…”

Section: Water Scattering By Fully Submerged Barriers Behind An Undul...mentioning

confidence: 99%

“…Scattered water waves under the combined effects of permeable barriers and undulation bottoms were investigated. Following Kaligatla, et al [47], the wave period of the incident wave was arranged as T = 8 sec, and the permeable parameter was set to G = (1 + i)k 1,0 . Therefore, the jth fully submerged barrier is located at x = v j = jv 1 , as shown in Figure 10.…”

Section: Water Scattering By Fully Submerged Barriers Behind An Undul...mentioning

confidence: 99%

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Bragg Resonance of Water Waves by Multiple Permeable Thin Barriers over Periodic Breakwaters

Tran¹,

Lin

Tsai

2023

Water

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In this study, the Bragg resonance of water waves scattered by multiple permeable thin barriers over a series of periodic breakwaters was solved by employing the eigenfunction matching method (EMM). The geometrical configuration was divided into multiple shelves separated by steps, on which thin permeable barriers were implemented. The solution was approximated using eigenfunctions with unknown coefficients that were considered as the amplitudes of the water waves for each shelf. The conservations of mass and momentum were then applied to form a system of linear equations, which was sequentially solved by a sparse-matrix solver. The proposed method degenerates to traditional EMM formulations if thin barriers, the permeability of the barrier, or bottom undulations are not considered. The validity of the suggested method was examined based on the results in the literature. Bragg resonances by bottom-standing, surface-piecing, and fully submerged permeable barriers over a series of periodic trapezoidal or half-cosine breakwaters were studied. In addition, the breakwater amplitudes, permeable parameters of the barriers, and incident angles of water wave scattering by different types of periodic breakwaters were discussed.

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Effect of bottom topography on wave scattering by multiple porous barriers

Cited by 26 publications

References 27 publications

Using a porous-media approach for CFD modelling of wave interaction with thin perforated structures

Using a porous-media approach for CFD modelling of wave interaction with thin perforated structures

Influence of Impermeable Elevated Bottom on the Wave Scattering due to Multiple Porous Structures

Bragg Resonance of Water Waves by Multiple Permeable Thin Barriers over Periodic Breakwaters

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