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A numerical study of hydrodynamic influence on collision of brash ice with a structural plate

Journal of Hydrodynamics 2022年第1期34卷 43-51页

作者： Li Zhou zhi zong Jia-nan Li School of Naval Architecture Dalian University of TechnologyDalian116024China Tianjin Branch HuaDian Heavy Industries Co.Ltd Tianjin300010China

The ice-structure collision is a transient process, which is further complicated by the presence of the water. It remains unclear how important the hydrodynamic influences are during the collision. This problem is partially investigated in this paper using numerical methods. To simplify the problem as much as possible without loss of generality, a short ice cylinder of circular section is assumed to collide with a vertical large structure plate under a variety of collision scenarios. Among them the most important cases are: (1) the rigid ice cylinder collision with the rigid or elastic structural plate at different collision velocities, (2) the elastic ice cylinder collision with the rigid or elastic structural plate at different collision velocities and (3) the elastoplastic ice cylinder collision with the rigid or elastic structural plate at different collision velocities. The numerical results show that: (1) the hydrodynamic influences are negligible in the first case, (2) the hydrodynamic influences in the second and third cases are not negligible, and become very significant in the third case. The influences are numerically estimated to be in the range of 20%–60% in terms of the momentum change. If the ice response is approximately decomposed into the rigid-body motions and the deformation modes at the instant of the collision with the structure, the previous conclusions show that the hydrodynamic influences on the rigid-body motions of the ice are negligible, but those on the elastic and elastoplastic modes of the ice are significant. Comparison with the case of a submerged ice cylinder (although not a practical case) reveals that the hydrodynamic influences are small in the first case due to the fact that the energy loss is used to produce the water splash and the cavity behind the ice cylinder. Through this study we come into the conclusion that the hydrodynamic influences are not important for the rigid-body motions, but important for the elastic or elastoplastic modes.

关键词： Ice-structure collision hydrodynamic influence numerical rigid mode elastic mode

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The fungal mycobiome:a new hallmark of cancer revealed by pan-cancer analyses

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Signal Transduction and Targeted Therapy 2023年第3期8卷 872-873页

作者： zhi zong Fangfang Zhou Long Zhang International Biomed-X Research Center Second Affiliated Hospital of Zhejiang University School of MedicineZhejiang University310058 HangzhouChina Institute of Biology and Medical Science Soochow University215123 SuzhouChina MOE Key Laboratory of Biosystems Homeostasis&Protection and Innovation Center for Cell Signaling Network Life Sciences InstituteZhejiang University310058 HangzhouChina Cancer Center Zhejiang University310058 HangzhouChina

In a recent study published in Cell,1 a group led by Ravid Straussman and Rob Knight characterized fungi across multiple types of cancer and revealed their distribution,relationships with immune cells,and possible prognostic value.Meanwhile,another study led by Anders B.Dohlman and Iliyan D.Iliev2 reported a similar pan-cancer mycobiome analysis of diverse body sites and identified tumor-associated fungi.

关键词： cancer fungal value.

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Numerical study of air layer drag reduction of an axisymmetric body in oscillatory motions

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Journal of Hydrodynamics 2021年第5期33卷 1007-1018页

作者： Xiao-jie Zhao zhi zong Yi-chen Jiang School of Shipbuilding Engineering Dalian University of TechnologyDalian 116024China School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian 116024China

The air layer drag reduction(ALDR)of an axisymmetric body in oscillatory motions is investigated in this paper with open source toolbox OpenFOAM.The unsteady Reynolds-averaged Navier-Stokes(URANS)equations are used to determine the viscous flow and the volume of fluid(VOF)model is adopted to capture the interface of the air-water two-phase flow.The k-e turbulence model is adopted to simulate the turbulence.The dynamic mesh technique is applied to model the movement of the axisymmetric body.Firstly,the ALDR results are validated by the experimental data.Then,the effects of the movements of the body on the drag reduction during the ALDR state are investigated.Two representative kinds of movements are considered,namely,the pitch and the heave.The numerical results show that the drag reduction varies during the movements and the average drag reduction rates will be reduced.The variation of the drag reduction is related to the morphological change of the air layer.The heave motion is more likely to reduce the effects of the ALDR than the pitch motion.For both oscillatory motions,the large motion amplitude and the low motion period are not conductive to improving the effects of the ALDR.The effects of the oscillatory motion on the ALDR are more sensitive at high water speeds than at low water speeds.Besides,increasing the air flow ratio can be considered as one way to improve the effects of the ALDR.

关键词： Air layer drag reduction volume of fluid(VOF)model axisymmetric body pitch heave numerical simulation

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农地确权、“三权分置”与增收效应——基于集体与农户的双重视角

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山西财经大学学报 2024年第1期46卷 40-53页

作者：刘宗志周力南京农业大学经济管理学院江苏南京210095

以农地“三权分置”为切入点,研究农地确权的增收效应。基于劳动力动态调查(CLDS)数据研究发现,实行“三权分置”前农地确权的增收效应有限,“三权分置”后,农地确权显著促进村集体经济及农户的收入增长。机制分析表明,“三权分置”后... 详细信息

以农地“三权分置”为切入点,研究农地确权的增收效应。基于劳动力动态调查(CLDS)数据研究发现,实行“三权分置”前农地确权的增收效应有限,“三权分置”后,农地确权显著促进村集体经济及农户的收入增长。机制分析表明,“三权分置”后的农地确权通过促进农地向新型经营主体集中,进而增加集体经济收入,同时通过优化农户要素配置增加农户收入。异质性分析显示,“三权分置”后的农地确权促进东部地区村集体经济收入增长和中西部地区农户收入增加。

关键词： “三权分置” 农地确权集体经济农户收入新型经营主体

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A boundary element method for the simulation of non-spherical bubbles and their interactions near a free surface

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Acta Mechanica Sinica 2012年第1期28卷 51-65页

作者： Zhang-Rui Li Lei Sun zhi zong Jing Dong State Key Laboratory of Structural Analysisfor Industrial EquipmentSchool of Naval Architecture Dalian University of Technology116023 DalianChina Grenland Group(China)Ltd. 201206 ShanghaiChina

The basic principle and numerical technique for simulating two three-dimensional bubbles near a free surface are studied in detail by using boundary element method. The singularities of influence coefficient matrix are eliminated using coordinate transformation and so-called 4π rule. The solid angle for the open surface is treated in direct method based on its definition. Several kinds of configurations for the bubbles and free surface have been investigated. The pressure contours during the evolution of bubbles are obtained in our model and can better illuminate the mechanism underlying the motions of bubbles and free surface. The bubble dynamics and their interactions have close relation with the standoff distances, buoyancy parameters and initial sizes of bubbles. Completely different bubble shapes, free surface motions, jetting patterns and pressure distributions under different parameters can be observed in our model, as demon- strated in our calculation results.

关键词： Boundary element method- Singularities - Solid angle Bubble jetting

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基于SPH方法的二维液舱晃荡特性研究

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船舶力学 2024年第5期28卷 676-688页

作者：张之凡王越美李昌良张桂勇宗智大连理工大学船舶工程学院辽宁大连116024 大连理工大学工业装备与结构分析国家重点实验室辽宁大连116024 北京理工大学爆炸科学与技术国家重点实验室北京100081 中国石油大学(华东)石油工程学院山东青岛266580 高新船舶与深海开发装备协同创新中心上海200240

本文基于流固耦合动力学理论,建立二维液舱晃荡的光滑粒子流体动力学模型,并引入Dummy边界处理固定边界问题。首先,与实验结果对比验证模型的有效性;随后,分析不同横摇激励、多种载液率下自由液面的运动规律,研究液体抨击舱壁产生的压... 详细信息

本文基于流固耦合动力学理论,建立二维液舱晃荡的光滑粒子流体动力学模型,并引入Dummy边界处理固定边界问题。首先,与实验结果对比验证模型的有效性;随后,分析不同横摇激励、多种载液率下自由液面的运动规律,研究液体抨击舱壁产生的压力特性;在此基础上,设计单一隔板和组合隔板等不同制荡结构,探究共振频率、30%载液率下,自由液面形态和壁面冲击压力的特性。结果表明:在共振频率下,横摇幅值对压力峰值的影响最大;随着载液率的增加,壁面抨击压力双峰特性逐渐消失;当隔板尺度较小时,T型隔板更有利于降低压力的整体水平;双T型隔板可有效降低舱底冲击。

关键词： SPH方法 Dummy边界液舱晃荡抨击压力隔板结构设计

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低速船舶微气泡减阻数值研究

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船舶力学 2024年第3期28卷 368-378页

作者：赵晓杰宗智王加夏洪智超胡俊明江苏科技大学船舶与海洋工程学院江苏镇江212000 大连理工大学船舶工程学院辽宁大连116024 工业装备结构分析国家重点实验室辽宁大连116024 江苏省船舶与海洋工程装备技术创新中心江苏南通226100

为了研究船舶微气泡减阻规律,本文基于OpenFOAM中两相欧拉数值模型,对低速散货船进行微气泡减阻数值研究。对气液两相分别建立控制方程,考虑五种相间作用力及气泡聚合和破碎,采用考虑气泡影响的改进k-ε湍流模型,忽略自由面影响,采用叠... 详细信息

为了研究船舶微气泡减阻规律,本文基于OpenFOAM中两相欧拉数值模型,对低速散货船进行微气泡减阻数值研究。对气液两相分别建立控制方程,考虑五种相间作用力及气泡聚合和破碎,采用考虑气泡影响的改进k-ε湍流模型,忽略自由面影响,采用叠模模型研究喷气量、气泡直径、航速及吃水等因素对船舶微气泡减阻的影响,分析气体体积分数、湍流粘度和气泡直径分布等。结果表明:微气泡可以同时减少船舶摩擦阻力、粘压阻力和总阻力;喷气量直接影响减阻率,喷气量越大,减阻率越高;较小气泡的平均气体体积分数较大且气体分布更均匀,同时湍流运动粘度较小,可以更有效减阻;气泡沿着流向会聚并,气泡越小聚并越剧烈;较高航速和小吃水更有利于减阻。

关键词：两相欧拉模型微气泡减阻船舶摩擦阻力数值模拟

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Numerical Investigation on Two-dimensional Boundary Layer Flow with Transition

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Journal of Marine Science and Application 2014年第4期13卷 388-393页

作者： Yong Zhao Tianlin Wang zhi zong Transportation Equipment and Ocean Engineering College Dalian Maritime University Dalian 116026 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China School of Naval Architecture Dalian University of Technology Dalian 116024 China

作为在许多设计应用程序的一个基本问题，到骚乱的从 laminar 的转变在计算液体动力学(CFD ) 仍然是一个困难的问题。一过渡流动在的数字研究二维被雷纳兹进行在这份报纸的平均数字模拟(RANS ) 。骚乱模型戏在复杂流动模拟的一个重要角... 详细信息

作为在许多设计应用程序的一个基本问题，到骚乱的从 laminar 的转变在计算液体动力学(CFD ) 仍然是一个困难的问题。一过渡流动在的数字研究二维被雷纳兹进行在这份报纸的平均数字模拟(RANS ) 。骚乱模型戏在复杂流动模拟的一个重要角色，和四个先进骚乱模型被评估。摩擦抵抗系数的数字答案与在过渡地区的测量那个相比，它显示有修正的那个威尔科克斯(2006 )k- 模型是最好的候选人。平均无尺寸的速度介绍的 streamwise 的无尺寸的速度表演的数字、分析的解决方案的比较在过渡区域很快改正形状。而且，象骚乱动能，旋涡粘性，和雷纳兹应力那样的骚乱数量也被学习，它是有用的学习转变行为。

关键词：流动数值模拟二维边界层计算流体动力学湍流模型摩擦阻力系数雷诺应力 RANS

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Numerical simulation of micro-bubble drag reduction of an axisymmetric body using OpenFOAM

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Journal of Hydrodynamics 2019年第5期31卷 900-910页

作者： Xiao-jie Zhao zhi zong Yi-chen Jiang Yu Pan School of Naval Architecture Dalian University of TechnologyDalian 116024China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian 116024China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Dalian 116024China Liaoning Engineering Laboratory for Deep-Sea Floating Structures Dalian 116024China

The two-phase micro-bubble flow over an axisymmetric body is investigated using the OpenFOAM framework.The numerical model consists of an Eulerian-Eulerian two-fluid model with closure relationships for the interfacial momentum transfer to capture the multiphase flow,a standard A:-￡*model for the continuous phase and one turbulence model inside the OpenFOAM for the dispersed phase.The bubble sizes are calculated based on the solution of the transport equation of the interfacial area density.The simulations in this work are carried out with different air injection rates and different flow velocities.The effects of bubble size on drag reduction are analyzed.The numerical results are compared against some available experiments and other numerical simulations.The numerical results indicate that the airflow rate and air volume fraction within the boundary layer near the body play important roles in micro-bubble drag reduction.The frictional drag reduction effect by micro bubbles is larger for lower water speed,and the presence of the micro bubbles can increase the pressure resistance of the body.Drag reduction rates are generally higher when the bubble diameter is smaller.

关键词： Eulerian-Eulerian two-fluid model axisymmetric body micro bubbles drag reduction numerical simulation

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On the properties of the Rational Function Spectrum describing waves near islands and reefs in South China Sea

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Journal of Hydrodynamics 2021年第5期33卷 879-888页

作者： Yi-geng Wang zhi zong Li Zhou Xiao-long Liu Xue-kang Gu School of Naval Architecture Dalian University of TechnologyDalian 116024China China Ship Scientific Research Center Wuxi 214082China

On-site measurements show that water waves near islands and reefs in South China Sea exhibit different properties of wave energy distributions with regard to wave frequencies,among which the most prominent factor is the interplay of swells arising from the West Pacific Ocean and the local wind waves.Observations also show that the breaking waves continuously appear,containing more energy in high frequency components,and the nonlinear characteristics of the waves are important in adjusting the energy distribution.These properties may explain the large discrepancies between the well-accepted wave spectra(for example the P-M spectrum,Neumann spectrum,ITTC spectrum etc.)and the measured wave spectra near islands and reefs in South China Sea.Therefore,a new Rational Function Spectrum is proposed in this paper to describe waves near islands and reefs which turns out to show satisfactory accuracy.It well captures wave power distributions in the form of single and double peaks,at low-and high-frequency regions,as well as nonlinear scale power law.Based on the investigation of the measured data near an island in South China Sea,the relation between the parameters used in the Rational Function Spectrum and the statistical parameters of water waves(significant wave height and wave period)is established.It is noted that the wave properties at low-and high-frequencies are controlled by the local wind velocities at the wave growth stage,but remain constant at the wave decay stage.The parameter peak frequency is only dependent on the wave period corresponding to the maximum wave height.The parameter spectral peak is determined from the wave height and the wave period.These relations help to clarify the physical meanings of the parameters used in the Rational Function Spectrum,and thus provide an alternative spectral form to describe random waves near islands and reefs.

关键词： Rational Function Spectrum double peak near islands and reefs swell nonlinear

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