Wave‐current Models for Design of Marine Structures

Ismail, Nabil M.

doi:10.1061/(asce)0733-950x(1984)110:4(432)

Cited by 22 publications

(10 citation statements)

References 8 publications

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“…They have then been applied to marine structures. () For ocean renewable energy application, they have been used for studying the performance of marine current turbines,() and the result was found to be consistent with experimental results . This analytical model has been also used in fatigue loading analysis of offshore wind turbines considering the wave‐current interaction where a fixed‐bottom wind turbine was studied.…”

Section: Introductionmentioning

confidence: 68%

“…For small‐amplitude waves propagating on currents, the resulting velocity fields are represented by the sum of the flow due to the current and the wave as

u_{T} (x,z,t) = U(z) + u(z) \cos false(κ normalx - ω normalt false),

w_{T} (x,z,t) = w(z) \sin false(κ normalx - ω normalt false),

p_{T} (x,z,t) = - ρ gz + p(z) \cos false(κ normalx - ω normalt false),

where ρ is the density of water, g is the gravitational acceleration, and κ and ω are the wavenumber and the angular frequency of the wave, respectively. Note that ω is the apparent frequency considering the current effect . Correspondingly, u T (x,z,t) and w T (x,z,t) are the total flow velocities in horizontal and vertical directions and p T is the total pressure, while u(x,z,t), w(x,z,t), and p(x,z,t) are the corresponding wave like first‐order terms …”

Section: Wave‐current Interaction Modelsmentioning

confidence: 99%

“…Note that is the apparent frequency considering the current effect. 16 Correspondingly, u T (x,z,t) and w T (x,z,t) are the total flow velocities in horizontal and vertical directions and p T is the total pressure, while u(x,z,t), w(x,z,t), and p(x,z,t) are the corresponding wave like first-order terms. 28 In Airy wave theory, 36 the free surface elevation is written as…”

Section: Regular Wave-current Interaction Modelmentioning

confidence: 99%

“…The first difficulty has been overcome recently as many dynamic models have been developed in the last several years . The latter issue, modeling wave‐current interactions, is still challenging; however, in the regime of linear waves on uniform currents, there are validated analytical models available for offshore structure design . Modeling wave‐current interactions considering nonlinear waves and varying current profile is an ongoing topic.…”

Section: Introductionmentioning

confidence: 99%

“…15 The latter issue, modeling wave-current interactions, is still challenging; however, in the regime of linear waves on uniform currents, there are validated analytical models available for offshore structure design. 16 Modeling wave-current interactions considering nonlinear waves and varying current profile is an ongoing topic. The interested readers are referred to previous studies [17][18][19][20][21][22][23] for some recent developments.…”

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confidence: 99%

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Wave‐current interaction effects on structural responses of floating offshore wind turbines

Chen

Basu

2018

Wind Energy

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This paper proposes a model considering the wave‐current interactions in dynamic analyses of floating offshore wind turbines (FOWTs) and investigates the interaction effects on the FOWT responses. Waves when traveling on current are affected by the current, leading to frequency shift and shape modification. To include such interactions in FOWT analysis, which has not been considered by the researchers till date, a nonlinear hydrodynamic model for multicable mooring systems is presented that is able to consider the cable geometric nonlinearity, seabed contact, and the current effect. The mooring model is then coupled with a spar‐type FOWT model that handles the structural dynamics of turbine blades and tower, aerodynamics of the wind‐blade interaction, and wave‐current effects on the spar. The analytical wave‐current interaction model based on Airy theory considering the current effect is used in the computation of flow velocity and acceleration. Numerical studies are then carried out based on the NREL offshore 5‐MW baseline wind turbine supported on top of the OC3‐Hywind spar buoy. Two cases, (1) when the currents are favorable and (2) when the currents are adverse, are examined. Differences of up to 15% have been observed by comparing the cable fairlead tension obtained excluding and including the wave‐current interactions. In particular, when irregular waves interact with adverse current, a simple superposition treatment of the wave and the current effects seems to underestimate the spar motion and the cable fairlead tension. This indicates that the wave‐current interaction is an important aspect and is needed to be considered in FOWT analysis.

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Section: Introductionmentioning

confidence: 68%

“…For small‐amplitude waves propagating on currents, the resulting velocity fields are represented by the sum of the flow due to the current and the wave as