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A Cell-Centered Lagrangian Scheme with an Elastic-Perfectly Plastic Solid Riemann Solver for Wave Propagations in Solids

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Advances in Applied Mathematics and Mechanics 2022年第3期14卷 703-724页

作者： Qian Chen Li Li Jin Qi Zhiqiang Zeng baolin tian Tiegang Liu Institute of Applied Physics and Computational Mathematics Beijing 100094China LMIB and School of Mathematics and Systems Science Beihang UniversityBeijing 100191China

A cell-centered Lagrangian scheme is developed for the numerical simula-tion of wave propagations in one dimensional(1D)elastic-plasticﬂow.The classical elastic-plastic material model initially proposed by Wilkins is adopted.The linear elas-tic model(Hooke’s Law),perfectly plastic model and von Mises yield criterion are used to describe the constitutive relationship of elastic-plastic solid.The second-order ex-tension of this scheme is achieved by a linear reconstruction method.Various numer-ical tests are simulated to check the capability of this scheme in capturing nonlinear elastic-plastic waves.Compared with the well-developed operator splitting method used in simulating elastic-plasticﬂow,this scheme is more accurate due to the con-sideration of a list of 64 different types of the nonlinear elastic-plastic waves when constructing the elastic-perfectly plastic Riemann solver.The numerical simulations of typical examples show competitive results.

关键词： Elastic-plasticﬂow cell-centered Lagrangian scheme elastic-perfectly solid Riemann problem wave propagation

Watt Linkage–Based Legged Deployable Landing Mechanism for Reusable Launch Vehicle: Principle, Prototype Design, and Experimental Validation

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Engineering 2023年第1期20卷 120-133页

作者： Haitao Yu baolin tian Zhen Yan Haibo Gao Hongjian Zhang Huiqiang Wu Yingchao Wang Yuhong Shi Zongquan Deng State Key Laboratory of Robotics and Systems Harbin Institute of TechnologyHarbin 150080China Beijing Institute of Aerospace Systems Engineering Beijing 100076China

The reusable launch vehicle (RLV) presents a new avenue for reducing cost of space transportation. The landing mechanism, which provides landing support and impact absorption, is a vital component of the RLV at final stage of recovery. This study proposes a novel legged deployable landing mechanism (LDLM) for RLV. The Watt-II six-bar mechanism is adopted to obtain the preferred configuration via the application of the linkage variation approach. To endow the proposed LDLM with advantages of large landing support region, lightweight, and reasonable linkage internal forces, a multi-objective optimization paradigm is developed. Furthermore, the optimal scale parameters for guiding the LDLM prototype design is obtained numerically using the non-dominated sorting genetic algorithm-II (NSGA-II) evolutionary algorithm. A fully-functional scaled RLV prototype is developed by integrating the gravity-governed deploying scheme to facilitate unfolding action to avoid full-range actuation, a dual-backup locking mechanism to enhance reliability of structure stiffening as fully deployed, and a shock absorber (SA) with multistage honeycomb to offer reliable shock absorbing performance. The experimental results demonstrate that the proposed LDLM is capable of providing rapid and smooth deployment (duration less than 1.5 s) with mild posture disturbance to the cabin (yaw and pitch fluctuations less than 6°). In addition, it provides satisfactory impact attenuation (acceleration peak less than 10g (g is the gravitational acceleration)) in the 0.2 m freefall test, which makes the proposed LDLM a potential alternative for developing future RLV archetype.

关键词： Reusable launch vehicle(RLV) Deployable mechanism Optimization desi gn

Transport diffuse interface model for simulation of solid-fluid interaction

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Applied Mathematics and Mechanics(English Edition) 2019年第3期40卷 321-330页

作者： Li LI Qian CHEN baolin tian Institute of Applied Physics and Computational Mathematics

For solid-fluid interaction, one of the phase-density equations in diffuse interface models is degenerated to a "0 = 0" equation when the volume fraction of a certain phase takes the value of zero or unity. This is because the conservative variables in phasedensity equations include volume fractions. The degeneracy can be avoided by adding an artificial quantity of another material into the pure phase. However, nonphysical waves,such as shear waves in fluids, are introduced by the artificial treatment. In this paper,a transport diffuse interface model, which is able to treat zero/unity volume fractions, is presented for solid-fluid interaction. In the proposed model, a new formulation for phase densities is derived, which is unrelated to volume fractions. Consequently, the new model is able to handle zero/unity volume fractions, and nonphysical waves caused by artificial volume fractions are prevented. One-dimensional and two-dimensional numerical tests demonstrate that more accurate results can be obtained by the proposed model.

关键词： solid-fluid interaction diffuse interface model phase-density equation Mie-Gruneisen equation of state(EOS) Eulerian method

Numerical investigation of Richtmyer-Meshkov instability driven by cylindrical shocks

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Acta Mechanica Sinica 2006年第1期22卷 9-16页

作者： baolin tian Dexun Fu Yanwen Ma LNM Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China

In this paper, a numerical method with high order accuracy and high resolution was developed to simulate the Richtmyer-Meshkov（RM） instability driven by cylindrical shock waves. Compressible Euler equations in cylindrical coordinate were adopted for the cylindrical geometry and a third order accurate group control scheme was adopted to discretize the equations. Moreover, an adaptive grid technique was developed to refine the grid near the moving interface to improve the resolution of numerical solutions. The results of simulation exhibited the evolution process of RM instability, and the effect of Atwood number was studied. The larger the absolute value of Atwood number, the larger the perturbation amplitude. The nonlinear effect manifests more evidently in cylindrical geometry. The shock reflected from the pole center accelerates the interface for the second time, considerably complicating the interface evolution process, and such phenomena of reshock and secondary shock were studied.

关键词： Richtmyer-Meshkov instability Atwoodnumber cylindrical shock

Galectin-7 overexpression destroys airway epithelial barrier in transgenic mice

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Integrative Zoology 2021年第2期16卷 270-279页

作者： Jing tian Ruxuan HE Yimu FAN Qianqian ZHANG baolin tian Chunju ZHOU Chunyan LIU Mingjing SONG Shunying ZHAO Department of Respiratory Medicine II Beijing Children’s HospitalCapital Medical UniversityNational Center for Children’s HealthBeijingChina Virus Laboratory Beijing Children’s HospitalCapital Medical UniversityNational Center for Children’s HealthChina Key Laboratory of Human Disease Comparative Medicine National Health Commission of China(NHC)Beijing Engineering Research Center for Experimental Animal Models of Human DiseasesInstitute of Laboratory Animal SciencePeking Union Medicine CollegeChinese Academy of Medical SciencesBeijingChina

When the integrity of airway epithelium is destroyed,the ordered airway barrier no longer exists and increases sensitivity to viral infections and allergens,leading to the occurrence of airway inflammation such as asthma.Here,we found that galectin-7 transgenic(+)mice exhibited abnormal airway structures as embryos and after birth.These abnormalities included absent or substantially reduced pseudostratified columnar ciliated epithelium and increased monolayer cells with irregular arrangement and widening of intercellular spaces.Moreover,airway tissue from galectin-7 transgenic(+)mice showed evidence of impaired cell–cell junctions and decreased expression of zonula occludens-1(ZO-1)and E-cadherin.When treated with respiratory syncytial virus(RSV)or ovalbumin(OVA),galectin-7 transgenic(+)mice developed substantially increased bronchial epithelial detachment and apoptosis,airway smooth muscle and basement membrane thickening,and enhanced airway responsiveness.We found that Galectin-7 localized in the cytoplasm and nucleus of bronchial epithelial cells,and that increased apoptosis was mediated through mitochondrial release of cytochrome c and upregulated JNK1 activation and expression of caspase-3 in galectin-7 Tg(+)mice.These findings suggested that Galectin-7 causes airway structural defects and destroys airway epithelium barrier,which predispose the airways to RSV or OVA-induced epithelial apoptosis,injury,and other asthma responses.

关键词： airway epithelial barrier epithelial apoptosis galectin-7

A Gas Kinetic Scheme for the Simulation of Compressible Multicomponent Flows

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Communications in Computational Physics 2013年第10期14卷 1347-1371页

作者： Liang Pan Guiping Zhao baolin tian Shuanghu Wang Institute of Applied Physics and ComputationalMathematics Beijing 100088China Key Laboratory of Computational Physics Institute of Applied Physics and ComputationalMathematicsBeijing 100088China The Graduate School of China Academy of Engineering Physics Beijing 100088China National Natural Science Foundation of China Beijing 100085China

In this paper,a gas kinetic scheme for the compressible multicomponent flows is presented by making use of two-species BGK model in[A.D.Kotelnikov and D.C.Montgomery,A Kinetic Method for Computing Inhomogeneous Fluid Behavior,J.Comput.Phys.134(1997)364-388].Different from the conventional BGK model,the collisions between different species are taken into consideration.Based on the Chapman-Enskog expansion,the corresponding macroscopic equations are derived from this two-species model.Because of the relaxation terms in the governing equations,the method of operator splitting is applied.In the hyperbolic part,the integral solutions of the BGK equations are used to construct the numerical fluxes at the cell interface in the framework of finite volume method.Numerical tests are presented in this paper to validate the current approach for the compressible multicomponent flows.The theoretical analysis on the spurious oscillations at the interface is also presented.

关键词： Multicomponent flows two-species BGK model Chapman-Enskog expansion gas kinetic scheme

APPLICATION OF MFCAV RIEMANN SOLVER TO MAIRE＇S CELL-CENTERED LAGRANGIAN METHOD

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Journal of Computational Mathematics 2015年第2期33卷 128-145页

作者： Yan Liu baolin tian Weidong Shen Shuanghu Wang Song Jiang Dekang Mao Applied Physics and Computational Mathematics Beijing 100095 P. R. China Department of Mathematics Shanghai University Shanghai 200444 P. R China

In this paper, we apply arbitrary Riemann solvers, which may not satisfy the Maire＇s requirement, to the Maire＇s node-based Lagrangian scheme developed in [P. H. Maire et al., SIAM J. Sci. Comput, 29 （2007）, 1781-1824]. In particular, we apply the so-called Multi-Fluid Channel on Averaged Volume （MFCAV） Riemann solver and a Riemann solver that adaptively combines the MFCAV solver with other more dissipative Riemann solvers to the Maire＇s scheme. It is noted that neither of the two solvers satisfies the Maire＇s requirement. Numerical experiments are presented to demonstrate that the application of the two Riemann solvers is successful.

关键词： Maire＇s node-based Lagrangian scheme Riemann solvers Riemann invariants,weighted least squares procedure.

爆轰驱动多介质问题的Lagrange多分区自适应数值模拟研究

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力学学报 2023年第11期55卷 2675-2692页

作者：周蕊李理田保林北京应用物理与计算数学研究所北京100094 北京大学应用物理与技术研究中心北京100091

凝聚炸药爆轰驱动惰性金属材料形成的多介质流动问题广泛存在于工程应用领域,Lagrange方法由于其物质界面的高保真特性一直在相关问题的数值模拟中发挥着不可替代的作用.加密网格是提高爆轰驱动多介质问题模拟精度的常用途径之一.然而,L... 详细信息

凝聚炸药爆轰驱动惰性金属材料形成的多介质流动问题广泛存在于工程应用领域,Lagrange方法由于其物质界面的高保真特性一直在相关问题的数值模拟中发挥着不可替代的作用.加密网格是提高爆轰驱动多介质问题模拟精度的常用途径之一.然而,Lagrange框架下整体密网格计算常会遇到网格畸变、计算效率低等问题.为此,针对爆轰驱动多介质流动问题,提出了一种Lagrange框架下的非结构网格多层自适应方法,在保证所关心区域局部网格分辨率的前提下,大幅缩减了整体计算规模,提升了Lagrange计算的健壮性.设计了非结构网格多层数据结构,提出了多层网格分层存储、有效网格压至一层进行Lagrange计算的AMR策略,同时还发展了自适应接触滑移耦合算法,实现了AMR计算与多分区接触滑移计算的“紧耦合”.相比于已有工作,所提出的AMR方法既保持了非结构网格多层数据结构的灵活性优势,又避免了Lagrange框架下多层网格分别计算带来的层间耦合困难,同时因实现了与接触滑移的自适应耦合,使得它能很好地适应多分区的多介质问题.在一维、二维爆轰算例验证所提出方法正确性的前提下,开展了拐角爆轰、多层炸药隔爆和有限尺寸弯道爆轰等复杂爆轰弹塑性多介质问题的数值模拟研究.计算结果显示,采用Lagrange非结构多层AMR数值模拟方法,可以有效捕捉凝聚炸药爆轰与惰性金属材料相互作用过程中的波系结构,可节省90%以上的网格规模.该方法对复杂几何边界、复杂波系结构和多分区相互作用等问题具有良好的适应性,为后续开展凝聚炸药爆轰约束问题的机理研究奠定了坚实的基础.

关键词：炸药爆轰多介质 Lagrange方法非结构网格多层自适应

可压缩湍流混合的高精度数值模拟研究（英文）

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可压缩湍流混合的高精度数值模拟研究（英文）