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Time-Dependent Tsunami Source Following the 2018 Anak Krakatau Volcano Eruption Inferred from Nearby Tsunami Recordings

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China ocean engineering 2021年第1期35卷 145-152页

作者： ZHU Yi-fan AN Chao WANG Teng LIU Hua Key Laboratory of Hydrodynamics(Ministry of Education) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China School of Earth and Space Sciences Peking UniversityBeijing 100871China

The eruption of the Anak Krakatau volcano,Indonesia,on 22 December 2018 induced a destructive tsunami(the Sunda Strait tsunami),which was recorded by four nearby tidal *** this study we invert the tsunami records and recover the tsunami generation *** tsunami sources are obtained,a static one of instant initial water elevation and a time-dependent one accounting for the continuous evolution of water *** time-dependent results are found to reproduce the tsunami recordings more *** complete tsunami generation process lasts approximately 9 min and features a two-stage evolution with similar *** stage lasts about 3.5 min and elevates a water volume of about 0.13 *** time,duration and volume of the volcano eruption in general agree with seismic records and geomorphological *** also test different sizes of the potential source region,which lead to different maximum wave height in the source area,but all the results of time-dependent tsunami sources show the robust feature of two stages of wave *** results imply a time-dependent and complex process of tsunami generation during the volcano eruption.

关键词： 2018 Anak Krakatau tsunami static tsunami source time-dependent tsunami source tsunami source inversion

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Comparison of different control strategies for brushless direct current (BLDC) motors on AUVs 33rd

Comparison of different control strategies for brushless dir...

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33rd International ocean and Polar engineering Conference, ISOPE 2023

作者： Jiang, Sijie Zhang, Baoquan Shuai, Changgeng Yu, Saier National Key Laboratory on Ship Vibration and Noise Naval University of Engineering Hubei Wuhan China Laboratory of Low Frequency Electromagnetic Communication Technology with the 722 Research Institute CSSC Hubei Wuhan China School of Naval Architecture & Ocean Engineering Huazhong University of Science and Technology Hubei Wuhan China School of Electrical Engineering Xi'an Jiaotong University Shaanxi Xian China

ISBN: (纸本)9781880653807

The research of BLDC motors control has become the key to the overall control characteristics of AUVs. This paper presents a comparison study on three most popular control strategies for BLDC motors. These three strategies are six-step commutation control (SCC), field-oriented control (FOC) and direct torque control (DTC). After a series of simulations and evaluations of these three control strategies which are performed using actual parameters of BLDC motors powered by an MOSFET inverter, a conclusion about the comparison from multiple aspects on different control strategies in these simulation experiments will be revealed. © 2023 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Pulse width modulation

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Modeling free surface flow pass solid obstructions by Immersed Boundary Method (IBM) 32nd

Modeling free surface flow pass solid obstructions by Immers...

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32nd International ocean and Polar engineering Conference, ISOPE 2022

作者： Luo, Pengxuan Zhang, Jingxin School of Naval Architecture Ocean & Civil Engineering Shanghai Jiao Tong University Shanghai China MOE Key Laboratory of Hydrodynamics Shanghai Jiao Tong University Shanghai China

ISBN: (纸本)9781880653814

Immersed Boundary Method (IBM) is used to numerically model boundaries with complex geometry and moving boundaries in the fixed grid system. The core idea of this method is to add virtual force terms into momentum equations to replace physical boundaries in the computational domain. The virtual force term is used to meet the boundary conditions in a body non-fitted grid system. In this paper, a numerical model combined IBM for free surface flow has been developed. The main algorithm is based on the framework of codes in-house. The model is used to simulate the fluid-structure interaction with the uniform flow and solitary wave in the present work. In the first part, the fundamental governing equations and numerical method of IBM model are briefly introduced. The core algorithm of immersed boundary identification and interpolation method is described in detail in this part. In the second part, a classical numerical case of flow around a cylinder under Re = 40 is used to validate this model. And a study case with experimental results of solitary wave interacting with vertical cylinders is designed to prove the practicability of the model. The free surface elevations recorded at eight wave gauges were used to validate the simulations. The numerical cases show that the model achieves good results with enough stability and accuracy. © 2022 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Solitons

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Energy harvesting by applying VIV with a circular cylinder and galloping with a triangle cylinder in a low-speed water flume 32nd

Energy harvesting by applying VIV with a circular cylinder a...

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32nd International ocean and Polar engineering Conference, ISOPE 2022

作者： Shen, Yu Wang, Jiasong School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai China MOE Key Laboratory of Hydrodynamics Shanghai Jiao Tong University Shanghai China

ISBN: (纸本)9781880653814

This paper presents energy harvesting results by applying vortex-induced vibration (VIV) and galloping excited with a circular cylinder and a triangular cylinder, respectively in a low-speed water flume. The voltage and power were obtained by the energy harvesters under different resistances (0-∞) and flow velocities (0.05~0.35m/s). The results demonstrate that for the VIV harvester, when the flow velocity increases, the voltage and power of the cylindrical cantilever beam increase initially, then decrease. The harvested maximum power density is 97.09μW/cm3 at the flow velocity of 0.16m/s. For the galloping harvester, the voltage and power of the triangular cylinder cantilever beam increase with the increase of flow velocity. The harvested maximum power density is 502.04μW/cm3 at the flow velocity of 0.35m/s. The triangular cylindrical cantilever beam has better performance in energy collection efficiency because of applying the galloping response of structure. © 2022 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Flow velocity

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Numerical investigation of the ship propeller load under reversed propulsion condition

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Journal of hydrodynamics 2021年第2期33卷 361-369页

作者： Xiang Fan Jin-jing Tang Yu-xin Zhang Hai-su Sun Yi-qing Gu Jing-xin Zhang Shanghai Merchant Ship Design and Research Institute Shanghai 201203China Key Laboratory of Hydrodynamics(Ministry of Education) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Stopping maneuver is an important research topic in ship *** stopping ability of ship is not only related to the hydrodynamic characteristics of hull,rudder and propeller,but also related to the capacity of main ***,there are few researches on the capacity of main engine under reversed propulsion *** the paper,a numerical water tank is established to simulate the propeller loads using the computational fluid dynamics(CFD)software STAR CCM+.The numerical model is firstly validated by experimental data,and then is used to investigate the propeller loads on a full-scale model with different ship speed and propeller *** dimensionless,the relations between the advance coefficient and the load coefficients are shown as J-KT curves and J-KQ ***,the flow structures near the propeller and the pressure on the propeller with different J values are *** simulations reveal that the flow velocities induced by the reversed propulsion of the propeller is similar to the wake flow by ship with J=-*** is the reason for the minimum points of J-KT and J-KQ curve occurring in cases with J=-***,the capacity of the main engine and the output load of the propeller are considered *** relations between the ship speeds and the maximum output loads on the propeller are discussed in details.

关键词： Propeller load reverse propulsion computational fluid dynamics(CFD)simulation

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The Tcn-Lstm Deep Learning Model for Real-Time Prediction of Ship Motions

SSRN

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SSRN 2023年

作者： He, Guolian Chaobang, Yao Guohua, Dong Xiaoshuai, Sun School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology Wuhan China Hubei Key Laboratory of Naval Architecture and Ocean Engineering Hydrodynamics HUST Wuhan China China Marine Development and Research Center Beijing China

Real-time and accurate ship motion prediction is of great significance for safe navigation and maritime decision-making. The difficulty lies in the nonlinearity and randomness of ship motion. The long short-term memory model has a strong nonlinear processing capability, which provides a potential way. However, the shortcoming of LSTM makes it difficult to achieve long-term dependencies motion prediction tasks. In present study, a hybrid model by combination of temporal convolutional network and long short-term memory (TCN-LSTM) is proposed, aiming at improving the performance of LSTM model. Based on the ship motion data collected in the Bohai Sea, the performance of the new model is analyzed. It can be found that the TCN-LSTM model can solve longer temporal durations prediction problem than LSTM model. Moreover, the TCN-LSTM model has good applicability under different ship navigation states, and the prediction accuracy is higher with a maximum improvement of 53.43%. Meanwhile, the performance of TCN-LSTM model under different input-output strategies are investigated. Numerical results show that TCN-LSTM has good prediction ability in both strategies, and the prediction accuracy is higher than 99% at the error level of 10%. The TCN-LSTM model has good superiority and applicability for nonlinear and random ship motions prediction. © 2023, The Authors. All rights reserved.

关键词： Forecasting

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Improved Delayed Detached Eddy Simulation of the NACA0015 Airfoil Stalled Flows 15

Improved Delayed Detached Eddy Simulation of the NACA0015 Ai...

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15th Asia Conference on Mechanical and Aerospace engineering, ACMAE 2024

作者： Ma, Kaifang Wang, Jiasong School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai200240 China MOE Key Laboratory of Hydrodynamics Shanghai Jiao Tong University Shanghai200240 China SJTU-Sanya Yazhou Bay Institute of Deepsea Science and Technology Sanya572024 China

ISBN: (纸本)9781643685892

Three-dimensional numerical simulations of the flow around the NACA 0015 airfoil were conducted by using the unsteady Reynolds-averaged Navier-Stokes (URANS) and improved delayed detached eddy simulation (IDDES) based on k-ω shear stress transport (SST) turbulence model. The angle of attack range (AoA) is from 0° to 75°. The solver in this paper is developed on an in-house platform HRAPIF based on the finite volume method (FVM) with the elemental velocity vector transformation (EVVT) approach. It uses a density-based method with a low Mach preconditioning technique to accelerate convergence. The inviscid spatial discretization is the 5th-order modified weighted essentially non-oscillatory (WENO-Z) scheme. The results show that the IDDES model can effectively predict lift and drag coefficients at all the studied AoAs and has significant advantages over URANS, both in predicting aerodynamic forces and in simulating flow vortex structures at post-stall AoAs. © 2025 The Authors.

关键词： Navier Stokes equations

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Research on mechanism-data dual-driven ship manoeuvring mathematical modeling 34th

Research on mechanism-data dual-driven ship manoeuvring math...

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34th International ocean and Polar engineering Conference, ISOPE 2024

作者： Shen, Wenhe Liu, Jialun Hu, Xinjue Li, Shijie Zhang, Song State Key Laboratory of Maritime Technology and Safety Wuhan University of Technology Hubei Wuhan China School of Naval Architecture Ocean and Energy Power Engineering Wuhan University of Technology Hubei Wuhan China Hubei Longzhong Laboratory Wuhan University of Technology Xiangyang Demonstration Zone Xiangyang China Intelligent Transportation Systems Research Center Wuhan University of Technology Hubei Wuhan China School of Transportation and Logistics Engineering Wuhan University of Technology Hubei Wuhan China

ISBN: (纸本)9781880653784

Ship dynamics models are the foundation to predict ship movement. Traditionally, mechanism-driven models have low accuracy and datadriven models have high data dependency. Thus, a novel mechanismdata dual-driven method is proposed to address the above problems. An MMG model is constructed to generate virtual data for the offline identification. An online model is established with reference to the offline model. The online model is trained by two state-of-the-art online algorithms, kernel adaptive projection and projection support vector machine. It has been verified that the proposed method can improve the prediction accuracy and reduce the data dependency. © 2024 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Support vector machines

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Research on Multi-objective Comprehensive Optimization of Underwater Vehicle’s Resistance and Wake Performance 33rd

Research on Multi-objective Comprehensive Optimization of Un...

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33rd International ocean and Polar engineering Conference, ISOPE 2023

作者： Zhu, Wenda Wang, Jian Feng, Baiwei Key Laboratory of High Performance Ship Technology Wuhan University of Technology Ministry of Education Hubei Wuhan China School of Naval Architecture Ocean and Energy Power Engineering Wuhan University of Technology Hubei Wuhan China China Ship Development and Design Center Hubei Wuhan China

ISBN: (纸本)9781880653807

The rapidity is an important index to measure the shape of underwater vehicles, the resistance and wake performance are important components that can not be ignored. The energy saved from propulsion power of the vehicle, which is often hundreds of kilowatts, can provide greater redundancy to the power *** on the DARPA SUBOFF AFF-8 model, this paper takes the underwater resistance and average wake as the optimization object, uses the parametric geometry reconstruction method to deform the hull line, and uses the uniform design test method to obtain uniformly distributed test samples in the design *** the long computation time required for direct optimization, the radial basis function neural network method was used to construct an approximate model after evaluating the resistance and average wake performance of the test samples with the help of CFD solver, and the results obtained by the approximate model and the numerical calculation results were ***, NSGA-II algorithm is used to find the optimization in the design space with constraints. After obtaining the Pareto front, several optimized ship types that meet the requirements are selected. After numerical calculation and verification, the performance of the optimized ship type is compared and analyzed with that of the parent ship type. The research results show that: (1) Full parametric modeling techno-logy can provide a better deformation scheme for the shape optimization of underwater vehicles. By exploring the relationship between optimization variables and characteristic parameters, it can ensure the surface smoothness of the model while only selecting a few control parameters to achieve the deformation of the vehicle body;(2)According to SUBOFF, under the premise of meeting the engineering constraints, the approximate model evaluation and optimization algorithm are combined to optimize the resistance and wake performance of underwater vehicle, which can accurately predict th

关键词： Multiobjective optimization

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Numerical investigation of aerodynamic and wake characteristics of a twin-rotor floating wind turbine: Under different wind directions 33rd

Numerical investigation of aerodynamic and wake characterist...

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33rd International ocean and Polar engineering Conference, ISOPE 2023

作者： Zhang, Zhihao Han, Zhaolong Zhou, Dai Bao, Yan Zhu, Hongbo Zhao, Yongsheng School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai200240 China Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure Shanghai Jiao Tong University Shanghai200240 China Key Laboratory of Hydrodynamics of Ministry of Education Shanghai Jiao Tong University Shanghai200240 China

ISBN: (纸本)9781880653807

The large size of wind turbines has posed many problems, an ideal alternative that is the multi-rotor wind turbine, has received attention. The deployment of a tightly arranged two-rotor floating wind turbine can theoretically improve power generation. Thus, it is high priority to understand in detail the physical mechanisms of aerodynamic and wake interference for different arrangements of two-rotor floating wind turbines. In this study, we investigate in detail the power and wake characteristics of two floating horizontal-axis wind turbines (FHAWTs) arranged side-by-side based on Unsteady Reynolds Averaged Navier Stokes (URANS) model. The aerodynamic and wake characteristics of a twin-rotor floating turbine are compared in detail under surge motion with three different wind directions (0°, 45°, 90°). When the twin rotors are arranged in tandem, the mean power output of the system is reduced by 44%. This study can deliver a scenario for the tight arrangement method of floating wind farms. © 2023 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Wakes

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