Fatigue damage prediction of top tensioned riser subjected to vortex-induced vibrations using artificial neural networks

Ocean Engineering, Journal Year: 2022, Volume and Issue: 268, P. 113393 - 113393

Published: Dec. 18, 2022

Several marine structures are subjected to critical loads resulting in their fatigue failure. Among these structures, the riser is an essential component that transports hydrocarbons and fluids from platform subsea well vice versa. Risers vortex-induced vibrations (VIV) caused by current, leading damage (Lekkala et al., 2022a; 2022b). Therefore, developing a simplified valid approach estimate behaviour necessary. Though semi-empirical methods available for analysis, deployments demand immense computational time costs. In this study, we propose novel framework based on data-driven analysis utilising artificial neural networks (ANN) predict VIV-induced of top-tensioned (TTR). To build reliable database, OrcaFlex, SHEAR7, used riser's modal due VIV, respectively. A total 24,686 models combinations eight input parameters (outer diameter riser, wall thickness water depth, surface, bottom velocities, top tension, buoyancy modules thickness, coverage ratio) corresponding output as results training multi-layered ANN. The prediction surrogate model has been achieved tuning hyperparameters improve model's accuracy. findings ANN-based confirm ANN exhibits mean absolute percentage error (MAPE) between predictions truths SHEAR7 9.29%. Also, proposed can reduce cost compared conventional methods. Finally, detailed parametric investigations carried out using optimised evaluate accuracy with tool. These metrics suggest method could be determine risers real-world field conditions.

Language: Английский

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Three-dimensional wake transition of rectangular cylinders and temporal prediction of flow patterns based on a machine learning algorithm

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(9)

Published: Sept. 1, 2024

This study investigates the three-dimensional (3D) wake transition in unconfined flows over rectangular cylinders using direct numerical simulation (DNS). Two different cross-sectional aspect ratios (AR) and Reynolds numbers (Re) are scrutinized: AR = 0.5 at Re 200 3 600. The investigation focuses on characterizing flow patterns forecasting their temporal evolution utilizing proper orthogonal decomposition (POD) technique coupled with a long short-term memory (LSTM) network. DNS results reveal emergence of an ordered mode A for 3, attributed to stabilizing effect elongated AR. On other hand, case smaller (= 0.5) exhibits mode-swapping regime characterized by modes B's distinct simultaneous manifestation. spanwise wavelengths B approximately 4.7 1.2 D 0.5, while wavelength is 3.5 3. POD serves as dimensionality reduction technique, LSTM facilitates prediction. algorithm demonstrates satisfactory performance predicting patterns, including instabilities B, across both transverse directions. employed adeptly predicts pressure time series surrounding cylinders. duration training only about 0.5% required computations. research, first time, effectiveness POD–LSTM complex 3D instantaneous past

Language: Английский

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Vortex-induced vibration and wake interference of two-degree-of-freedom elastically mounted elliptical cylinders in tandem at various spacing

Ocean Engineering, Journal Year: 2024, Volume and Issue: 310, P. 118637 - 118637

Published: July 8, 2024

Language: Английский

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Machine Learning Approach for Flow Fields Over a Circular Cylinder Based on Particle Image Velocimetry Measurements

Measurement, Journal Year: 2023, Volume and Issue: 223, P. 113699 - 113699

Published: Oct. 13, 2023

Language: Английский

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Prediction model for multidirectional vortex-induced vibrations of catenary riser in convex/concave and perpendicular flows

Journal of Fluids and Structures, Journal Year: 2023, Volume and Issue: 117, P. 103826 - 103826

Published: Jan. 20, 2023

This study presents an advanced numerical prediction model based on nonlinear wake oscillators for the investigation of multidirectional vortex-induced vibration (VIV) responses a long catenary riser depending structural curved configuration versus incoming flow direction. By considering uniform free-stream aligned with initial curvature plane in convex or concave shape, normal velocity component is nonlinearly sheared owing to spanwise variation inclination angles. different from perpendicular case which spatially constant. To capture influence direction three-dimensionally coupled cross-flow and in-line VIV, distributed are introduced applied simulate fluctuating hydrodynamic lift drag forces that account important effects cylinder inclination, variable vortex excitation frequencies, global–local​ displacement relationships, relative flow-cylinder velocities. The amplified mean force axial tangential also considered. These empirical equations three-dimensional motion, overall governing numerically solved assess multimode, multi-frequency multi-degree-of-freedom responses. Validation carried out VIV flexible straight cylinders experimental results literature. Parametric investigations performed by varying velocities perpendicular, configurations low mass-damping ratio. In-plane (horizontal vertical) out-of-plane features presented discussed terms space–time amplitudes, drag-amplified shape reconfigurations, oscillation lock-in occurrences, dual resonances, orbital motion trajectories, fluid–structure energy transfer, multimodal contributions. Overall highlight geometric orientation characteristics should be recognised incorporated into practical analysis tools.

Language: Английский

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Proper orthogonal decomposition method of constructing a reduced-order model for solving partial differential equations with parametrized initial values

Partial Differential Equations in Applied Mathematics, Journal Year: 2024, Volume and Issue: 9, P. 100654 - 100654

Published: Feb. 24, 2024

This paper proposes a novel proper orthogonal decomposition method for constructing reduced-order model. model effectively computes solutions various initial conditions in time-dependent partial differential equations. The mode obtained from the proposed captures both fluctuating component and mean-field of solution. In this mode, eigenvalues representing mean-field, are significantly larger than those component. Consequently, determining number modes required solution cannot rely solely on cumulative contribution rate. Therefore, gives scalar weight to controls magnitude energy. We propose that considers scaler alongside ratio modes. was evaluated using Burgers equation with parametric values. Our selects appropriate represent given dataset, unlike conventional method. A based time evolutions datasets several parameters by imposing condition exceeds 98%.

Language: Английский

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Numerical investigation of flow past a cylinder using cumulant lattice Boltzmann method

Physics of Fluids, Journal Year: 2024, Volume and Issue: 36(3)

Published: March 1, 2024

This paper presents simulations of flow past a circular cylinder within the subcritical Reynolds number (Re) range from 3900 to 2 × 105, utilizing parameterized cumulant lattice Boltzmann model. In this study, three-dimensional characteristic boundary condition for incompressible has been integrated into method at outflow minimize spurious reflection. The field, wake statistics, hydrodynamic force, and power spectra results Re = model are exhaustively compared with laboratory data other numerical models. Relative models employing turbulence closure, demonstrate enhanced agreement experimental even relatively coarser grid resolution. resolution-spanning feature in turbulent flows, without using explicit model, aligns previous benchmark case studies. stability-preserving regularization process present is analyzed. Results indicate that influence parameter mitigated improved A specific around recommended. Variations properties forces 105 confirm can accurately simulate practical engineering characterized by complex separation recirculation, range. Moreover, computational efficiency parallel scalability methods.

Language: Английский

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Geometrical investigation of forced convective flows over staggered arrangement of cylinders employing constructal design

International Communications in Heat and Mass Transfer, Journal Year: 2024, Volume and Issue: 155, P. 107553 - 107553

Published: May 9, 2024

The current numerical work conducted a geometrical investigation of forced convective flows over staggered arrangement four cylinders applying constructal design. main objectives are to determine designs maximizing the Nusselt number (NuD) and minimizing drag coefficient (CD) at three distinct Reynolds numbers (ReD = 10, 40, 150) considering Pr 0.71. problem involves two constraints: cross-sectional area occupation arrangement, degrees freedom: ST/D, SL1/D SL2/D. These represent ratios between transversal pitch, longitudinal pitch frontal intermediate cylinders, posterior diameter. introduction pitches enabled an exploration generation asymmetrical patterns in flow direction. Results indicated strong dependency design on number. Moreover, configurations generally benefited both performance indicators for present conditions. most favorable arrangements fluid dynamics were achieved with lowest more concentrated ReD 40 150. Concerning thermal purpose, highest magnitude ST/D led NuD. For near upstream one; length increases downstream one, 150, occupied all slight asymmetry.

Language: Английский

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Numerical Investigation of Flow and Heat Transfer from Twin Circular Cylinders Present in Double Forward-Facing Step

Fluids, Journal Year: 2025, Volume and Issue: 10(2), P. 48 - 48

Published: Feb. 12, 2025

A numerical simulation of the circular cylinder as an obstacle in a double forward-facing (DFFS) step was performed. The size and position upstream (c1) downstream (c2) were varied to explore their role heat transfer both laminar turbulent conditions. Comparative results upper lower half plotted understand flow characteristics around due effect cylinder’s dimension position. For Re = 800, when c1 is placed near bottom wall, it pair rear-side symmetrical vortices, c2 vortices become larger shifted towards top wall. Additional separation happens adjacent steps greater than c2. These strongly influence convection from step. However, Reynolds number (Re) increased 800 80,000, these vortices’ decreased. When moves 0.375H 0.75H, average Nusselt significantly. Moreover, hike higher irrespective obstacles. significantly enhances wall rather

Language: Английский

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Wake Characteristics of a Circular Cylinder with a Short Flat Plate at an Angle in one of the Separated Shear Layers

Flow Measurement and Instrumentation, Journal Year: 2025, Volume and Issue: unknown, P. 102931 - 102931

Published: May 1, 2025

Language: Английский

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