Numerical investigation of local scour around USAF with different hydraulic conditions under currents and waves

Peng, Yu; Hu, Ruigeng; Yang, Jinmu; Liu, Hongjun

doi:10.1016/j.oceaneng.2020.107696

Cited by 26 publications

(10 citation statements)

References 54 publications

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“…ln T * = −2.58U cw + 3.48 (10) Similar to the results of Welzel et al [29] and Petersen et al [40] for the jacket and single pile, the linear formula (see Figure 6) was used to fitting the present data in the range of 0.347 < U cw < 0.739. As shown in Figure 6, the linear formula can well depict the relationship between T* and U cw .…”

Section: Time Scalementioning

confidence: 62%

“…In ocean environments, waves generally coexist with current [9]. The local scour around monopiles in combined waves and current involves the interaction between fluids, monopile and sediments, and the scour processes may be more complicated than the conditions of waves-only or current-only [9][10][11]. Due to the blockage effects of foundation, the adverse pressure gradient emerged at the upside of monopile, resulting in a separation of wave-current boundary layer close to the seabed, and it made the formation of horseshoe vortexes [3,12,13].…”

Section: Introductionmentioning

confidence: 99%

“…According to Eadie and Herbich [17], compared with the condition of current-only, the time scale to reach the equilibrium state decreased and the equilibrium scour depth increased significantly in combined waves and current. The equilibrium scour depth in combined waves and current is related with KC number and the ratio of velocities U cw (=U c /(U c + U wm )), in which U c denotes the undisturbed near-bed current velocity and U wm represents the maximum undisturbed wave-induced oscillatory flow velocity above the wave boundary layer [10,12,14,18]. The adverse pressure gradient at the upside of monopile increased apparently when a current was superimposed on waves, and the higher U c /U m led to the lower critical KC number for the threshold of horseshoe vortex [9,15,16,18].…”

Section: Introductionmentioning

confidence: 99%

“…The adverse pressure gradient at the upside of monopile increased apparently when a current was superimposed on waves, and the higher U c /U m led to the lower critical KC number for the threshold of horseshoe vortex [9,15,16,18]. The scour around a single pile occurred when KC > 6 in waves [3,12], but the scour was initiated even when KC < 6 in combined waves and current [10,13,19]. For a relatively small KC (KC < 4), the equilibrium scour depth around a single pile could be still great when U cw ≥ 0.6 [9,15,18].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study of Local Scour around Tripod Foundation in Combined Collinear Waves-Current Conditions

Wang

Liu

et al. 2021

JMSE

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A series of laboratory experiments were conducted in a wave-current flume to investigate the scour evolution and scour morphology around tripod in combined waves and current. The tripod model was made using the 3D printing technology, and it was installed in seabed with three installation angles α = 0°, 90°and 180° respectively. In the present study, the scour evolution and scour characteristic were first analyzed. Then, the equilibrium scour depth Seq was investigated. Furthermore, a parametric study was carried out to study the effects of Froude number Fr and Euler number Eu on equilibrium scour depth Seq respectively. Finally, the effects of tripod’s structural elements on Seq were discussed. The results indicate that the maximum scour hole appeared underneath the main column for installation angle α = 0°, 90° and 180°. The Seq for α = 90° was greater than the case of α = 0° and α = 180°, implying the tripod suffered from more severe scour for α = 90°. When KC was fixed, the dimensionless time scale T* for α = 90° was slightly larger than the case of α = 0° and α = 180° and the T* was linearly correlated with Ucw in the range of 0.347 < Ucw < 0.739. The higher Fr and Eu both resulted in the greater scour depth for tripod in combined waves and current. The logarithmic formula can depict the general trend of Seq and Fr (Eu) for tripod in combined waves and current.

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Section: Time Scalementioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental Study of Local Scour around Tripod Foundation in Combined Collinear Waves-Current Conditions

Wang

Liu

et al. 2021

JMSE

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“…Given that, an innovative foundation called umbrella suction anchor foundation (USAF) has been designed for nearshore wind power. The previous studies indicated the USAF was characterized by the favorable lateral bearing capacity with the low cost [6,13,14]. The close-up of USAF is shown in Figure 1, and it includes six parts: 1-interal buckets, 2-external skirt, 3-anchor ring, 4-anchor branch, 5-supporting rod, 6telescopic hook.…”

Section: Introductionmentioning

confidence: 99%

Scour Characteristics and Equilibrium Scour Depth Prediction around Umbrella Suction Anchor Foundation under Random Waves

Liu

Leng

et al. 2021

JMSE

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A series of numerical simulation were conducted to study the local scour around umbrella suction anchor foundation (USAF) under random waves. In this study, the validation was carried out firstly to verify the accuracy of the present model. Furthermore, the scour evolution and scour mechanism were analyzed respectively. In addition, two revised models were proposed to predict the equilibrium scour depth Seq around USAF. At last, a parametric study was carried out to study the effects of the Froude number Fr and Euler number Eu for the Seq. The results indicate that the present numerical model is accurate and reasonable for depicting the scour morphology under random waves. The revised Raaijmakers’s model shows good agreement with the simulating results of the present study when KCs,p < 8. The predicting results of the revised stochastic model are the most favorable for n = 10 when KCrms,a < 4. The higher Fr and Eu both lead to the more intensive horseshoe vortex and larger Seq.

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Numerical study on local scour characteristics around submarine pipelines in the Yellow River Delta silty sandy soil under waves and currents

Yu,

Hu,

Zhang

et al. 2024

Deep Underground Science and Engineering

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Due to their high reliability and cost‐efficiency, submarine pipelines are widely used in offshore oil and gas resource engineering. Due to the interaction of waves, currents, seabed, and pipeline structures, the soil around submarine pipelines is prone to local scour, severely affecting their operational safety. With the Yellow River Delta as the research area and based on the renormalized group (RNG) k‐ε turbulence model and Stokes fifth‐order wave theory, this study solves the Navier–Stokes (N–S) equation using the finite difference method. The volume of fluid (VOF) method is used to describe the fluid‐free surface, and a three‐dimensional numerical model of currents and waves–submarine pipeline–silty sandy seabed is established. The rationality of the numerical model is verified using a self‐built waveflow flume. On this basis, in this study, the local scour development and characteristics of submarine pipelines in the Yellow River Delta silty sandy seabed in the prototype environment are explored and the influence of the presence of pipelines on hydrodynamic features such as surrounding flow field, shear stress, and turbulence intensity is analyzed. The results indicate that (1) local scour around submarine pipelines can be divided into three stages: rapid scour, slow scour, and stable scour. The maximum scour depth occurs directly below the pipeline, and the shape of the scour pits is asymmetric. (2) As the water depth decreases and the pipeline suspension height increases, the scour becomes more intense. (3) When currents go through a pipeline, a clear stagnation point is formed in front of the pipeline, and the flow velocity is positively correlated with the depth of scour. This study can provide a valuable reference for the protection of submarine pipelines in this area.

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Numerical investigation of local scour around USAF with different hydraulic conditions under currents and waves

Cited by 26 publications

References 54 publications

Experimental Study of Local Scour around Tripod Foundation in Combined Collinear Waves-Current Conditions

Experimental Study of Local Scour around Tripod Foundation in Combined Collinear Waves-Current Conditions

Scour Characteristics and Equilibrium Scour Depth Prediction around Umbrella Suction Anchor Foundation under Random Waves

Numerical study on local scour characteristics around submarine pipelines in the Yellow River Delta silty sandy soil under waves and currents

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