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A method of constructing a database-free optimal dynamical system and a global optimal dynamical system

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Science china(Physics,Mechanics & Astronomy) 2008年第7期51卷 905-915页

作者： wu chuijie1? & wang liang2.1 state key laboratory of structural analysis for industrial equipment, dalian university of technology, dalian 11602., china 2 Research Center for Fluid Dynamics, School of Science, PLA university of Science and technology, Nanjing 2.1101, china 1. state key laboratory of structural analysis for industrial equipment Dalian University of Technology Dalian 116024 China 2. Research Center for Fluid Dynamics School of Science PLA University of Science and Technology Nanjing 211101 China

In this paper, to overcome the drawbacks of POT which minimize the reminder, not only the optimal functional with minimal residual is put forward, but also the method of global optimization is used. Under the condition of large reminder, the optimal bases can also be obtained through the method of POTres without the approaching of initial conditions. In addition, compared with local optimization, the advantage of global optimization is remarkable. On the one hand, we can expect that the dynamical system based on the global optimal bases will include more information than the ones based on the local optimal bases, since the global optimal bases are much more precise than the local optimal bases. On the other hand, from the point of view of error, the global optimal bases are independent of the choice of the object functional and the initial bases.

关键词： dynamical system residual global optimization

An adaptive version of ghost-cell immersed boundary method for incompressible flows with complex stationary and moving boundaries

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Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 923-932页

作者： wang liang1 & wu chuijie2,3 1 School of Science,PLA university of Science and technology,Nanjing 2.1101,china 2 state key laboratory of structural analysis for industrial equipment,dalian university of technology,dalian 11602.,china 3 School of Aeronautics and Astronautics,dalian university of technology,dalian 11602.,china 1. School of Science PLA University of Science and Technology Nanjing 211101 China2. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China3. School of Aeronautics and Astronautics Dalian University of Technology Dalian 116024 China

An adaptive version of immersed boundary method for simulating flows with complex stationary and moving boundaries is *** method employs a ghost-cell methodology which allows for a sharp representation of the immersed *** simplify the implementation of the methodology,a volume-of-fluid method is introduced to identify the immersed *** addition,the domain is spatially discretized using a tree-based discretization which is relatively simple to implement a fully flexible adaptive refinement ***,the methodology is validated by comparing it with numerical and experimental results on three cases:(1) the flow passing a circular cylinder at Re=40 and Re=100,(2) a periodic oscillation of a circular cylinder in fluid at rest and(3) the self-propelled fish-like swimming at Re=6400.

关键词： adaptive mesh refinement ghost-cell immersed boundary method moving boundaries

The Micro/Nanostructure Characteristics and the Mechanical Properties of Hemifusus tuba Conch Shell

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Journal of Bionic Engineering 2010年第4期7卷 3+308-313页

作者： Yan liang~1,Jie Zhao~2,Chengwei wu~1 1.state key laboratory of structural analysis for industrial equipment,Department of Engineering Mechanics,dalian university of technology,dalian 11602.,P.R.china 2.School of Materials Science and Engineering,dalian university of technology,dalian 11602.,P.R.china [a] state key laboratory of structural analysis for industrial equipment Department of Engineering Mechanics Dalian University of Technology Dalian 116024 P. R. China [b] School of Materials Science Engineering Dalian University of Technology Dalian 116024 P. R. China

The mollusk shell mobilizes calcium from environment for skeletal *** occurs through synthesizing solidsin solution in the presence of organic molecules of specific interior regions of the conch *** ultrastructure and microhardnessof the Hemifusus tuba conch shell living in the Huang/Bo sea area are investigated in the *** is shown that thecomposition and microstructure of the mollusk shell vary in different *** prodissoconch shell consists only of aragonitewith the crossed-lamellar *** the spiral shell and the body shell of the Hemifusus tuba conch shell arecomposed of one calcite layer and several aragonite *** calcite layer consists of cylindrical grains,but the aragonitelayers are crossed-lamellar ultrastructure at three size *** minimum structure size (the third-order lamella) is at about20 nm - 80 *** margin of shell aperture is only composed of calcite with cylindrical *** natural optimization of theshell microstructure is intimately due to the growth of the Organic *** different positions the microhardness of molluscshell is different due to different crystal structures and crystal *** growth process of shells allows a constantrenewal of the material,thus enabling their functional adaptation to external environments.

关键词： conch shell microstructure aragonite calcite crossed-lamellar

Large-eddy simulation of formation of three-dimensional aeolian sand ripples in a turbulent field

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 945-960页

作者： wu chuijie1,wang Ming2 & wang liang3 1 state key laboratory of structural analysis for industrial equipment,dalian university of technology,dalian 11602.,china 2 Yellow River Institute of Hydraulic Research,Zhengzhou 450003,china 3 Research Center for Fluid Dynamics,Science School,PLA university of Science and technology,Nanjing 2.1101,china state key laboratory of structural analysis for industrial equipment Dalian University of Technology Dalian 116024 China Yellow River Institute of Hydraulic Research Zhengzhou 450003 China Research Center for Fluid Dynamics Science School PLA University of Science and Technology Nanjing 211101 China

With the method of large-eddy simulation,the equation of spherule motion and the method of immersed boundary condition,numerical simulations of three-dimen-sional turbulent aeolian motion and the formation of sand ripples under three-di-mensional turbulent wind and the mutual actions of saltation and creeping motion were carried out. The resulting sand ripples have the form that is flat on the upwind side and steep on the leeward,which is identical to the sand ripples in nature. We also realized the self-restoration process of three-dimensional sand ripples,which shows the correctness of the method of numerical simulation and the models of saltation and creeping. Finally,We analyzed the influence of sand ripples on the three-dimensional turbulent wind field,and found that due to the appearance and development of sand ripples,in the normal direction of ground there exists stronger energy exchange,and moreover,there is close correspondence between the forms of sand ripples and the vorticity close to the ground surface.

关键词： large-eddy simulation equation of spherule motion sand ripples saltation creep

Numerical simulations of self-propelled swimming of 3D bionic fish school

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中国科学:技术科学 2010年第3期 334-334页

Numerical simulations of self-propelled swimming of a three dimensional bionic fish and fish school in a viscous fluid are carried *** is done with the assistance of a parallel software package produced for 3D moving boundary *** computational fluid dynamics package combines the adaptive multi-grid finite volume method,the immersed boundary method and VOF (volume of fluid) *** using the package results of the self-propelled swimming of a 3D bionic fish and fish school in a viscous fluid are *** comparison to the existing experimental measurements of living fishes,the predicted structure of vortical wakes is in good agreement with the measurements.

关键词： adaptive multi-grid immersed boundary method self-propelled swimming fish school 3D bionic fish

Where is the rudder of a fish?:the mechanism of swimming and control of self-propelled fish school

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Acta Mechanica Sinica 2010年第1期26卷 45-65页

作者： chuijie wu liang wang tate key laboratory of structural analysis for industrial equipment Dalian University of Technology 116024 Dalian China School of Aeronautics and Astronautics Dalian University of Technology 116024 Dalian China Research Center for Fluid Dynamics PLA Universityof Science and Technology 211101 Nanjing China

Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- and three-dimensional moving boundary problem, which combines the adaptive multi-grid finite volume method and the methods of immersed boundary and volume of fluid, it is found that due to the interactions of vortices in the wakes, without proper control, a fish school swim with a given flap- ping rule can not keep the fixed shape of a queue. In order to understand the secret of fish swimming, a new feedback con- trol strategy of fish motion is proposed for the first time, i,e., the locomotion speed is adjusted by the flapping frequency of the caudal, and the direction of swimming is controlled by the swinging of the head of a fish. Results show that with this feedback control strategy, a fish school can keep the good order of a queue in cruising, turning or swimming around circles. This new control strategy, which separates the speed control and direction control, is important in the construction of biomimetic robot fish, with which it greatly simplifies the control devices of a biomimetic robot fish.

关键词： Self-propelled swimming Feedback controlstrategy of fish swimming ~ Direction control - Locomotionspeed control Three-dimensional biomimetic fish

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基于SPH方法的二维液舱晃荡特性研究

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

Topology Optimization for Harmonic Excitation Structures with Minimum Length Scale Control Using the Discrete Variable Method

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Computer Modeling in Engineering & Sciences 2023年第6期135卷 1941-1964页

作者： Hongliang Liu Peijin wang Yuan liang Kai Long Dixiong Yang key laboratory of Liaoning Province for Composite structural analysis of Aerocraft and Simulation College of Aerospace EngineeringShenyang Aerospace UniversityShenyang110136China state key laboratory of structural analysis for industrial equipment Department of Engineering MechanicsDalian University of TechnologyDalian116023China state key laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing102206China

Continuumtopology optimization considering the vibration response is of great value in the engineering structure *** aimof this studyis toaddress the topological designoptimizationof harmonic excitationstructureswith minimumlength scale control to facilitate *** topology design based on discrete variables is proposed to avoid localized vibration modes,gray regions and fuzzy boundaries in harmonic excitation topology *** topological design model and sensitivity formulation are *** requirement of minimum size control is transformed into a geometric constraint using the discrete ***,thin bars,small holes,and sharp corners,which are not conducive to the manufacturing process,can be eliminated from the design *** present optimization design can efficiently achieve a 0–1 topology configuration with a significantly improved resonance frequency in a wide range of excitation ***,the optimal solution for harmonic excitation topology optimization is not necessarily symmetric when the load and support are symmetric,which is a distinct difference fromthe static optimization ***,one-half of the design domain cannot be selected according to the load and support *** examples are presented to demonstrate the effectiveness of the discrete variable design for excitation frequency topology optimization,and to improve the design manufacturability.

关键词： Discrete variable topology optimization harmonic excitation minimumlength scale control geometric constraint manufacturability

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面向应力约束的独立连续映射方法

力学学报 2019年第2期51卷 620-629页

作者：龙凯王选吉亮华北电力大学新能源电力系统国家重点实验室北京102206 大连理工大学工业装备结构分析国家重点实验室大连116024

大多数已有的拓扑优化研究为系统刚度最大化设计,尤其以体积比约束下的静态柔顺度最小化问题为典型.从工程角度出发,结构强度设计至关重要.以往的应力研究表明,应力约束拓扑优化存在着奇异性、约束数目庞大、高度非线性特性等诸多数值困... 详细信息

大多数已有的拓扑优化研究为系统刚度最大化设计,尤其以体积比约束下的静态柔顺度最小化问题为典型.从工程角度出发,结构强度设计至关重要.以往的应力研究表明,应力约束拓扑优化存在着奇异性、约束数目庞大、高度非线性特性等诸多数值困难.为了实现应力约束下的拓扑优化设计,采用归一化p范数应力指标以减少单元应力约束数目.遵循独立连续映射建模方式,引入密度变量的倒变量函数作为设计变量.推导了应力约束函数和体积目标函数对设计变量的敏度,并基于一阶和二阶泰勒近似得到各自的显式表达式.通过构造的系列二次规划子问题,原拓扑优化问题采用序列二次规划算法高效求解.二维数值算例考察了结构刚度和强度设计结果的异同,以及不同应力约束上限值对应力约束拓扑优化结果的影响.通过提出方法与传统变密度法结果的比较,说明提出的独立连续映射方法在应力约束下具有可行性和有效性.优化结果也表明了考虑应力约束的连续体拓扑优化具有必要性.

关键词：拓扑优化应力约束独立连续映射法序列二次规划连续体结构