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Simulation of the deformable lateral boundaries in biaxial test using DEM

Particuology 2024年第5期88卷 161-175页

作者： Ali Momeni Barry Clarke Yong Sheng Ali Hassanpour WSP 3 Wellington PlaceLeedsLS1 4APUK hull University HullHU6 7RXUK School of Civil Engineering University of LeedsLeedsLS2 9JTUK School of Computer Science University of HullHullHU6 7RXUK School of Chemical and Process Engineering University of LeedsLeedsLS2 9JTUK

Applying the discrete element method(DEM)in soil mechanics can provide abundant information at the particle-scale and facilitates illustration of the macro-mechanical behaviour of soils based on the inter-particle *** triaxial test is one of the most common laboratory methods to study the macro-mechanical behaviour of particulate materials such as ***,many problems in geotechnical design can be assumed and simplified as a plane strain *** a biaxial test can be conducted to reproduce the macro-mechanical behaviour of soil,where the sample is enclosed by two horizontal rigid platens and a vertical latex membrane,which is a deformable continuous element and allows the enclosed specimen to deform freely while maintaining confining stress during *** paper presents an algorithm to represent physical and mechanical characteristics of latex membrane in the 2D DEM simulation of biaxial test using the PFC^(2D) *** investigate the impact of the lateral boundary conditions on the micro-macro mechanical behaviours of soil samples,two sets of DEM biaxial tests are conducted,*** rigid and deformable lateral boundary *** DEM modeling results indicate that the lateral boundary conditions have a significant effect on the micro-scale fabric properties,thickness and inclination of the shear *** comparison between these two simulations also demonstrates that the lateral boundary conditions play a major role in the peak and post-peak stress-strain behaviours as well as the dilation and critical state behaviours of granular soils.

关键词： Discrete element method Biaxial test Deformable boundaries Shear band Critical state Fabric anisotropy Geometrical stability index

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Application of CFD and FEA Coupling to Predict Structural Dynamic Responses of A Trimaran in Uni-and Bi-Directional Waves

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China Ocean Engineering 2024年第1期38卷 81-92页

作者： LIAO Xi-yu XIA Jin-song CHEN Zhan-yang TANG Qin ZHAO Nan ZHAO Wei-dong GUI Hong-bin Marine design&Research Institute of China Shanghai 200011China Ship Structure Division China Ship Scientific Research CenterWuxi 214082China College of Ocean Engineering Harbin Institute of TechnologyWeihaiWeihai 264209China State Key laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of TechnologyDalian 116024China School of Foreign Studies Jiangnan UniversityWuxi 214122China

To predict the wave loads of a flexible trimaran in different wave fields,a one-way interaction numerical simulation method is proposed by integrating the fluid solver(Star-CCM+)and structural solver(Abaqus).Differing from the existing coupled CFD-FEA method for monohull ships in head waves,the presented method equates the mass and stiffness of the whole ship to the hull shell so that any transverse and longitudinal section stress of the hull in oblique waves can be ***,verification study and sensitivity analysis are carried out by comparing the trimaran motions using different mesh sizes and time step *** on the wave elevation of uni-and bi-directional waves is also carried *** a comprehensive analysis on the structural responses of the trimaran in different uni-directional regular wave and bi-directional cross sea conditions is carried out,***,the differences in structural response characteristics of trimaran in different wave fields are *** results show that the present method can reduce the computational burden of the two-way fluid-structure interaction simulations.

关键词： CFD-FEA fluid-structure coupling structural responses trimaran bi-directional cross sea

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Fully distributed dynamic event-triggered formation-containment tracking for multiagent systems with multiple types of disturbances

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Science China(Information Sciences) 2024年第1期67卷 168-186页

作者： Weihua LI Huaguang ZHANG Juan ZHANG Rui WANG College of Information Science and Engineering Northeastern University State Key laboratory of Synthetical Automation for Process Industries Northeastern University

This paper is dedicated to addressing the time-varying output formation-containment tracking(TVOFCT) problem for heterogeneous linear multiagent systems(MASs) with multiple types of disturbances under directed communication *** agents are divided into tracking leaders,formation leaders,and *** the output space,the formation leaders are required to form an expected geometric formation while tracking the tracking leader,and the followers are required to enter the convex hull spanned by formation ***,a disturbance observer is designed to observe the disturbance with deterministic ***,by combining adaptive technology with event-triggered technology,an independent fully distributed dynamic event-triggered(FDDET) compensator is designed to estimate the state of the tracking *** main advantages of this compensator lie in the following three aspects:(1) the adaptive weight does not increase unboundedly;(2) the interval time between events is expanded;(3) the design does not rely on any global *** to the design of this compensator,an independent FDDET convex hull observer is further designed to observe the convex hull spanned by formation ***,based on the designed disturbance observer,compensator,and convex hull observer,the adaptive disturbance rejection control input which can make the MASs achieve TVOFCT is ***,a numerical simulation is provided to clearly verify the validity of the theoretical results.

关键词： formation-containment tracking disturbance rejection multiagent systems fully distributed control dynamic event-triggered control

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Braking Performance of a Biomimetic Squid-Like Underwater Robot

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Journal of Bionic Engineering 2013年第3期10卷 265-273页

作者： Md. Mahbubar Rahman Sinpei Sugimori Hiroshi Miki Risa Yamamoto Yugo Sanada Yasuyuki Toda laboratory of hull form design Department of Naval Architecture and Ocean Engineering Graduate School of Engineering Osaka University Osaka 565-0871 Japan

In this study, the braking performance of the undulating fin propulsion system ofa biomimetic squid-like underwater robot was investigated through free run experiment and simulation of the quasi-steady mathematical model. The quasi-steady equa- tions of motion were solved using the measured and calculated hydrodynamic forces and compared with free-run test results. Various braking strategies were tested and discussed in terms of stopping ability and the forces acting on the stopping stage. The stopping performance of the undulating fin propulsion system turned out to be excellent considering the short stopping time and short stopping distance. This is because of the large negative thrust produced by progressive wave in opposite direction. It was confirmed that the undulating fin propulsion system can effectively perform braking even in complex underwater explorations.

关键词： biomimetics squid-like underwater robot undulating fin propulsion system braking performance motion simulation

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基于内聚力单元法的船舶与重叠冰碰撞数值模拟研究

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哈尔滨工程大学学报（英文版） 2024年第1期23卷 127-136页

作者：倪宝玉王亚婷徐莹陈绾绶 College of Shipbuilding Engineering Harbin Engineering UniversityHarbin 150001China Marine design&Research Institute of China Shanghai 200011China

The gradual increase in shipping and drilling activities in the Arctic regions has resulted in the increased importance of studying the structural safety of polar ships in various ice *** ice refers to a type of accumulated and overlapped sea ice;it is driven by external forces,such as wind and waves,and may exert high loads on ships and threaten their structural ***,the properties of rafted ice and the construction of numerical models should be studied before exploring the interaction and collision between ships and rafted *** on the nonlinear finite-element method,this paper introduces the cohesive element model for the simulation of rafted *** interaction between ships and rafted ice is studied,and the ice force of the hull is *** simulation results are compared with model test findings,and the effectiveness of the cohesive element method in the construction of the model of rafted ice materials is *** this basis,a multilayer rafted ice model is constructed,and its interaction with the ship is *** research unveils that rafted ice parts impede crack generation and slow down crack propagation to a certain extent.

关键词： Cohesive element method Rafted ice Rafting length Ship-ice collisions Finite element model Numerical simulation

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design and analysis of a novel dual source vapor injection heat pump using exhaust and ambient air

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能源与人工环境(英文) 2022年第1期3卷 95-104页

作者： Jing Li Yi Fan Xudong Zhao Xiaoman Bai Jinzhi Zhou Ali Badiei Steve Myers Xiaoli Ma Research Centre for Sustainable Energy Technologies University of HullHull HU67RXUK Environment design Centre School of Art and MediumHefei Normal UniversityHefei 230601China School of Mechanical Engineering Southwest Jiaotong UniversityChengduSichuanPR China

A novel dual source vapor injection heat pump(DSVIHP)using exhaust and ambient air is *** air exhausted from the building first releases energy to the medium-pressure evaporator and is then mixed with the ambient air to heat the low-pressure evaporator.A vapor injection(VI)compressor of two inlets is connected with the low and medium pressure ***’s first time that a VI compressor is employed to recover the ventilation *** system can minimize the ventilation heat loss and provide a unique defrosting approach by using the exhaust waste *** of the proposed DSVIHP are *** models are *** energetic and exergetic analyses are carried out under variable *** results indicate that the DSVIHP has superior thermodynamic *** superiority is more appreciable at a lower ambient *** has a higher COP than the conventional vapor injection heat pump and air source heat pump by 11.3%and 23.2%respectively at an ambient temperature of-10°C and condensation temperature of 45°*** waste heat recovery ratio from the exhaust air is more than 100%.The novel DSVIHP has great potential in the cold climate area application.

关键词： Dual source vapor injection heat pump Exhaust air Waste heat recovery COP Defrosting

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Ultralong nitrogen/sulfur Co-doped carbon nano-hollowsphere chains with encapsulated cobalt nanoparticles for highly efficient oxygen electrocatalysis

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Carbon Energy 2023年第8期5卷 15-30页

作者： Wei Zhang Xingmei Guo Cong Li Jiang-Yan Xue Wan-Ying Xu Zheng Niu Hongwei Gu Carl Redshaw Jian-Ping Lang College of Chemistry Chemical Engineering and Materials ScienceSoochow UniversitySuzhouChina State Key laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghaiChina College of Environmental and Chemical Engineering Jiangsu University of Science and TechnologyZhenjiangChina Department of Chemistry University of HullHullUK

The development of simple and effective strategies to prepare electrocatalysts,which possess unique and stable structures comprised of metal/nonmetallic atoms for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is currently an urgent ***,an efficient bifunctional electrocatalyst featured by ultralong N,S-doped carbon nano-hollow-sphere chains about 1300 nm with encapsulated Co nanoparticles(Co-CNHSCs)is *** multifunctional catalytic properties of Co together with the heteroatom-induced charge redistribution(i.e.,modulating the electronic structure of the active site)result in superior catalytic activities toward OER and ORR in alkaline *** optimized catalyst Co-CNHSC-3 displays an outstanding electrocatalytic ability for ORR and OER,a high specific capacity of 1023.6 mAh gZn^(-1),and excellent reversibility after 80 h at 10mA cm^(-2)in a Zn-air battery *** work presents a new strategy for the design and synthesis of efficient multifunctional carbon-based catalysts for energy storage and conversion devices.

关键词： Co nanoparticles N S co-doping oxygen electrocatalysts rechargeable Zn-air batteries ultralong carbon nano-hollow-sphere chains

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Numerical study on transom stern ventilation and resistance of high-speed ship in calm water

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Journal of Hydrodynamics 2022年第5期34卷 864-875页

作者： Hui Wang Ren-chuan Zhu Meng-xiao Gu Le Zha State Key laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Marine design and Research Institute of China Shanghai200011China

A transom stern is a common design feature for a high-speed *** the present study,the transom stern ventilation of NPL 3b,5b hull is investigated by three methods:H−H formula,Doctors’formula,and computational fluid dynamics(CFD)method at *** the CFD method,the ratios of the wave elevation and wetted area are used to determine the transom *** of results show that Doctors’formula is more accurate to calculate the critical transom draft Froude *** then a Rankine panel method(RPM)based on the high-order boundary element method incorporated the modified transom stern condition is implemented to evaluate the steady wave problem of a high-speed fishery patrol ship in calm ***,free-surface(FS)and double body(DB)simulations based on Star-CCM+are carried out to obtain the wave-making resistance and total *** results of the resistance and wave pattern around the fishery patrol ship computed by RPM show generally good agreement with experimental measurement and CFD *** results indicate that the developed Rankine panel method with transom condition could predict the resistance of high-speed displacement ships with good accuracy.

关键词： Transom ventilation computational fluid dynamics(CFD)method Rankine panel method(RPM) high-speed ship double body simulation resistance

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design and Development of a Lens-walled Compound Parabolic Concentrator-A Review

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Journal of Thermal Science 2019年第1期28卷 17-29页

作者： LI Guiqiang School of Engineering University of Hull

Compound parabolic concentrator(CPC) is a representative among solar concentrators, one of whose disadvantage is that the concentration ratio limits the half acceptance angle. Based on this, researchers put forward a novel structure, named the lens-walled CPC. This paper reviews the design and development of lens-walled CPC. The structure of the symmetric and asymmetric lens-walled CPC and the improved ones are presented, and their indoor and outdoor performances are also illustrated. The lens-walled CPC has a larger half acceptance angle and a more uniform flux distribution that is suitable for PV application. Furthermore, the life-cycle assessment for building integrated with PV is performed and it shows that the energy payback time of such integrated system has a significant advantage. In addition, future research areas are also indicated that may provide more functions and more stable performance. The design methods and developmental directions given in this study would provide many references in solar optical research and solar concentrator optimization.

关键词： compound parabolic concentrator lens-walled optical uniform flux distribution

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Numerical investigation of the influence of vortex generator on propeller cavitation and hull pressure fluctuation by DDES

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Journal of Hydrodynamics 2022年第3期34卷 444-450页

作者： Yun Long Han-qiao Han Bin Ji Xin-ping Long Wuhan Second Ship design and Research Institute Wuhan430064China State Key laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan430072China

In this study,the delayed detached eddy simulation(DDES)is coupled with a homogenous cavitation model to simulate the cavitating turbulent flow around a propeller behind a full body ship with special emphasis on the influence of the vortex generator(VG)on the propeller cavitation and the hull pressure *** small calculation uncertainty as evaluated by the DDES verification and validation(V&V)method indicates that the present simulation can accurately reproduce the propeller performance and cavitation,and the predicted hull pressure fluctuation is in a fairly good agreement with the available experimental *** mechanism is explored through the current numerical results how the VG affects the local velocity distribution,along with the influences of the VG on the propeller cavitation and the hull pressure *** is shown that the streamwise vortex is induced by the VG near the hull boundary *** very low velocity region in the hull wake is reduced due to the effect of the streamwise ***,the propeller cavitation develops more mildly and the hull pressure fluctuation decreases due to the influence of the VG.

关键词： Propeller cavitation delayed detached eddy simulation(DDES) vortex generator(VG) streamwise vortex

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