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Numerical simulations of faraday waves in cylindrical and hexagonal tanks based on MPS method

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Journal of Hydrodynamics 2023年第2期35卷 278-286页

作者： Cong-yi Huang Wei-wen Zhao De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

When a partially loaded liquid container vibrates along the vertical direction,the liquid inside will oscillate regularly,which is called Faraday wave.In some cases,the wave form of the Faraday wave is stable and smooth,and sometimes there is violent wave breaking and liquid splashing.In this paper,the Faraday waves inside the cylindrical tank and the hexagonal tanks are simulated by the in-house solver MLParticle-SJTU base on the moving particle semi-implicit(MPS)method.The surface tension model is used to better model the free surfaces with large deformations.Phenomena such as wave breaking and liquid splashing are well captured and simulated.The results show that the waveforms are significantly different at different excitation frequencies.And the tank shape also has an obvious effect on the waveform.

关键词： Faraday wave moving particle semi-implicit(MPS)method wave breaking liquid splash surface tension

Research progress on the hydrodynamic performance of water-air-bubble mixed flows around a ship

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Journal of Hydrodynamics 2022年第2期34卷 171-188页

作者： Zheng Li Xiao-song Zhang De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The interaction between ship and surrounding fluids generates the water-air-bubble mixed flow laden with numerous droplets and bubbles.The water-air-bubble mixed flow is a complex multi-phase flow phenomenon,which involves intense air-water mixture,complex evolution of interface shape,interactions between multi-scale flow structures and strong turbulent fluctuations.Based on the field observations at sea,a large range of white water-air-bubble flow exists widely around a large-scale sailing ship,and directly affects the hydrodynamic performance of ship from various aspects.This paper reviews the research progress of water-air-bubble mixed flow around a ship.Current knowledge about the formation and evolution mechanism are introduced firstly.Then,the effects of the water-air-bubble mixed flow on ship performance are further reviewed,the main concerns are ship resistance,propulsion performance,slamming and maneuverability.Finally,the future research prospects are summarized.

关键词： Water-air-bubble mixed flow ship resistance propulsion performance ship slamming characteristics maneuverability

Coupling potential and viscous flow models with domain decomposition for wave propagations

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Journal of Hydrodynamics 2022年第5期34卷 826-848页

作者： Wen-jie Zhong Wen-tao wang De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China China Ship Scientific Research Center Wuxi214082China

Either potential flow or viscous flow based model may be flawed for numerical wave simulations.The two-way coupling of potential and viscous flow models with the domain decomposition utilizing respective strengths has been a trending research topic.In contrast to existing literatures in which closed source potential models were used,the widely used open source OceanWave3D,OpenFOAM-v2012 are used in the present research.An innovative overlapping two-way coupling strategy is developed utilizing the ghost points in OceanWave3D.To guarantee computational stability,a relaxation zone used both for outlet damping and data transfer is built over the overlapping region in OceanWave3D.The free surface elevation in the relaxation zone is directly probed in OpenFOAM while the velocity potential is indirectly built upon its temporal variation which is calculated by the free surface boundary condition using the probed velocity.Strong coupling is achieved based on the fourth-order Runge-Kutta(RK)algorithm.Both two-and three-dimensional tests including linear,nonlinear,irregular,and multi-directional irregular waves,are conducted.The effectiveness of the coupling procedure in bidirectional data transfer is fully demonstrated,and the model is validated to be accurate and efficient,thus providing a competitive alternative for ocean wave simulations.

关键词： Domain decomposition numerical wave tank potential/viscous flow coupling irregular waves wave-structure interaction

Numerical simulations of sloshing waves in vertically excited square tank by improved MPS method

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Journal of Hydrodynamics 2022年第1期34卷 76-84页

作者： Guan-yu Zhang Wei-wen Zhao De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

Faraday wave is a phenomenon of sloshing due to a heave motion of a partially filled tank,which is also called parametric instability or parametric resonance.In the present paper,the phenomenon of faraday wave in a pure heave excited square tank is numerically simulated through the moving particle semi-implicit(MPS)method.The surface tension effect and a new Dirichlet boundary condition for the pressure Poisson equation are considered to avert unphysical fragmentation and clustering of particles in splash simulation.In the numerical simulation,the evolution of wave motion,and the non-linearity together with breaking phenomenon of faraday wave can be observed.The agreement is good in general,both amplitude and phase.Besides,the parameter studies including the excitation frequency and the forcing amplitude are carried out to analyses the mechanism of resonances response.

关键词： Liquid sloshing faraday wave moving particle semi-implicit(MPS)method surface tension MLParticle-SJTU solver

Correlation analysis between underwater noise and Liutex for DTMB4119 propeller

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Journal of Hydrodynamics 2022年第4期34卷 585-595页

作者： Lian-jie Yu Jian-wei Wu De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Wuhan Second Ship design and Research Institute Wuhan 430205China

Propeller is an important equipment of ocean structures.It has characteristics of complex geometry and periodic vortex shed,which means high research value.This paper takes DTMB419 propeller as the research object.A detailed study is conducted on the wake vortices in non-cavitation state and cavitation state.Three vortex identification methods are used to compare the vortices capture effects from downstream sections and three-dimensional perspectives.The results show that,the third-generation vortex identification technologyΩ_(R)shows obvious advantages.At the same time,FW-H equation is used to predict propeller noise,and the relationship between nonlinear sound source distribution and vortices distribution is analyzed.It is found that the distribution of Lighthill tensor is consistent withΩ_(R),which proves the advantages and potential of third-generation vortex identification technology from acoustic perspective.

关键词： Third-generation vortex DTMB4119 propeller cavitation FW-H formulation

Scale effects on bow wave breaking of KCS ship model:Insights from DdeS investigations

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Journal of Hydrodynamics 2023年第4期35卷 668-678页

作者： Jian-hua wang Wen-tao wang De-cheng wan Computational Marine Hydrodynamics Laboratory(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China China Ship Scientific Research Center Wuxi214082China

Ship bow wave breaking is a common phenomenon during navigation,involving complex multi-scale flow interactions.However,the understanding of this intense free surface flow issue is not sufficiently deep,especially regarding the lack of research on the impact of scale effects on bow wave breaking.This paper focuses on the benchmark ship model KCS and conducts numerical simulations and comparative analyses of bow wave breaking for three model scales under the condition of Fr=0.35.The numerical calculations were performed using the in-house computational fluid dynamics(CFD)solver naoe-FOAM-SJTU,which is developed on the open source platform OpenFOAM.delayed detached eddy simulation(DdeS)method is utilized to calculate the viscous flow field around the ship hull.The present method was validated through measurement data of wave profiles and wake flows obtained from model tests.Flow field results for three different scales,including bow wave profiles,vorticity at various sections,and wake distribution,were presented and analyzed.The results indicate that there is small difference in the bow wave overturning and breaking for the first two occurrences across different scales.However,considerable effects of scale are observed on the temporal and spatial variations of the free surface breaking pattern after the second overturning.The findings of this study can serve as valuable data references for the analysis of scale effects in ship bow wave breaking phenomena.

关键词： Scale effects wave pattern bow wave breaking KRSIO Container Ship(KCS) delayed detached eddy simulation(DdeS)approach

Omega-Liutex method for the interaction among wave, current and fixed vertical cylinder

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Journal of Hydrodynamics 2023年第1期35卷 83-94页

作者： Bo Han Zhi Pan Wei-wen Zhao De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Wuhan Second Ship design and Research Institute Wuhan430205China

This paper presents a numerical investigation of the interaction among wave,flow and a fixed cylinder using the naoe-FOAM-SJTU solver,which is a viscous solver for hydrodynamics based on OpenFOAM.The simulation considers the strong nonlinear interaction among a regular wave,flow,and a single fixed cylinder due to viscosity,which is common in offshore structures.The study focus on the vortex induced by viscosity and its significant role in hydrodynamic performance computation.A mesh convergence study is conducted prior to the simulation,and a proper set of mesh is chosen.The simultaneous generation of the regular wave and flow is realized using the numerical field boundary,and the wave propagation is validated.The results of wave elevation and pressures captured by wave gauges and probes around the fixed cylinder are compared with experiment results.The structure of vortices is displayed at significant times,and the phenomena of wave elevation and pressure changes around the cylinder are analyzed in detail using the Omega-Liutex identification method.

关键词： Wave-current interaction vortex Omega-Liutex method naoe-FOAM-SJTU solver numerical simulation

Numerical simulations of FPSO with sloshing tanks in a random freak waves

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Journal of Hydrodynamics 2022年第3期34卷 491-498页

作者： Yuan Zhuang Guo wang De-cheng wan Jian-wei Wu Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Marine design and Research Institute of China Shanghai200011China Wuhan Second Ship design and Research Institute Wuhan430205China

This paper presents a potential-viscous coupled method to simulate a floating production storage and offloading(FPSO)with two liquefied natural gas(LNG)sloshing tanks in a random freak wave.The potential theory uses high-order-spectral(HOS)method.The random wave is generated by HOS for 2000 s,and a freak wave is observed around 1830 s.The FPSO LNG model was firstly verified in regular waves using HOS-computational fluid dynamics(CFD)coupled method and validated the HOS-CFD coupled method can solve the ship motion coupled with sloshing tanks accurately.The FPSO with LNG tanks are then simulated in the freak wave,showed the coupling effects when the freak wave passes.With the existence of the sloshing tanks,the amplitude of the roll motion decreases and the period of roll motion changed.Wave breaking phenomenon can be observed when the wave crest of the freak wave encounters with the ship.

关键词： Ship motion with sloshing tank high-order-spectral-computational fluid dynamics(HOS-CFD)method naoe-FOAM-SJTU solver freak waves

Hydrodynamic performances and wakes induced by a generic submarine operating near the free surface in continuously stratified fluid

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水动力学研究与进展B辑:英文版 2023年第3期35卷 396-406页

作者： Liu-shuai Cao Gang Gao En-kai Guo De-cheng wan School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The wake of a submarine is a crucial element that greatly affects its stealth and hydrodynamic performance.To investigate the propagation and evolution characteristics of submarine wakes in a stratified fluid,particularly under free surface conditions,a numerical method to simulate the linearly stratified environment was developed.A thermocline model based on Boussinesq assumption was introduced to match the continuously stratified fluid.The volume of fluid(VOF)method was utilized to capture free surface waves,while a fully structured grid and the SST k-ωturbulence model were combined to solve the complex flow of submarines.Grid independence study in homogenous flow near the free surface was initially conducted.Furthermore,the hydrodynamic performance,wake evolution characteristics,free surface signatures as well as decay of velocity under different stratification levels were analyzed.Results demonstrated that the numerical method employed was efficient in simulating stratified flows.Moreover,it showed that density stratification had a significant impact on the hydrodynamics and wake characteristics of a submarine,especially under strong density stratification circumstances.

关键词： Wakes submarine free surface stratified fluid hydrodynamics