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基于Shan-Chen模型的格子Boltzmann方法在微流动模拟研究中的应用 总被引:1,自引:0,他引:1
对格子Boltzmann方法的本质及Shan-Chen模型的核心机制进行了全面阐述, 并从应用实例角度对基于Shan-Chen模型的格子Boltzmann方法在微流动模拟方面的有效性、适应性进行了详细分析. 结果表明, Shan-Chen模型易于耦合微观条件下占主导作用的微观力, 拓宽了格子Boltzmann方法在微流动模拟方面的应用. 同时, Shan-Chen模型在润湿性边界条件表征方面的优势, 使得这种方法在微结构表面的滑移效应模拟方面具有很好的应用前景. 相似文献
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应用耗散粒子动力学方法研究了胶体微泵.每个胶体小球按照既定的运动规律相继运动,从而可驱动流体.首先利用耗散粒子动力学方法计算了泊肃叶流动,验证了模拟的正确性.然后模拟了由六个胶体小球组成的周期性胶体微泵的工作过程.胶体颗粒与周围流体粒子之间采用了弹性碰撞模型;模拟中选择了合适的参数,从而可提高流体的粘度并保证DPD流体的不可压缩性.模拟结果与他人的实验数据进行了对比,两者很好吻合.模拟结果显示,胶体微泵的无量纲流量的绝对值随着小球运动ω的变小而增大;而随着ω的减小,无量纲流量的振幅也相应变大. 相似文献
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基于压力隧洞模型的复合材料横向热残余应力分析 总被引:1,自引:1,他引:0
考虑碳纤维横向刚度情况下,将复合材料横向热残余应力问题简化为压力隧洞模型.利用该模型推导出复合材料固化成型过程中形成的横向热残余应力,其中分析得出了单纤维与树脂的接触压力以及该压力传递到纤维和树脂后的分布情况.结果表明接触压力传递到纤维内部后成一固定值,传递到树脂后以正比于r.函数衰减.在其基础上提出场叠加方法,得出纤维之间相互耦合的接触压力与残余应力场.通过有限元模拟,理论模型和数值模拟基本一致. 相似文献
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在衡量单个细胞力学行为的研究中,越来越多地采用结合实验的数值模拟方法. 在连续介质力学框架下,发展了一种新的心肌细胞本构模型,并与微管吮吸实验结合,探讨了心肌细胞的力学特性. 本构模型是对普遍使用的仅能用于小变形分析的标准线性固体模型的一种扩展,它将超弹性性能引入到黏弹性模型中,用以描述细胞的大变形黏弹性效应. 基于改进的本构模型,对心肌细胞微管吮吸实验过程进行了有限元模拟,并将计算结果与实验结果以及经典理论解进行了对比. 结果显示发展的本构模型适合细胞大变形问题的有限元数值模拟. 相似文献
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提出一种新的基于能量非局部模型的应变梯度理论,并应用此理论对多晶铜以及薄膜基底的微压痕硬度进行理论预测和数值分析. 首先,提出了能量非局部模型,并由此模型,得出新应变梯度理论的本构关系;其次,由变分原理,得出相应的有限元公式;再次,给出了微压痕硬度的有限元分析方法;最后,将该理论预测结果与经典理论预测结果以及实验结果进行了对比. 结果表明,计算结果与实验结果相符;而经典理论的预测结果远低于实验结果. 相似文献
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将变分多尺度方法应用于一维缆索模型,导出受力缆索的宏观有限元模型并求得细观位移解析解,总结出变分多尺度方法应用于具体模型的关键点和缺陷. 假定刚度为常值,数值模拟一定边界和受力下的缆索,得到宏观和细观位移. 将细观与宏观位移叠加,相比于精确位移得出:细观位移可视为常规有限元模型的后验误差. 变分多尺度方法在一维力学模型中的成功应用,推进了其实用性,为其在更多力学及工程问题中的运用和发展提供了参考. 相似文献
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本文使用VOF方法将微液滴在粗糙壁面上的接触现象转化为不可压缩两相流动问题,并对其进行三维数值模拟.选择具有柱形突起和槽道两种微结构的壁面进行模拟.计算了不同粗糙系数时液滴在突起结构表面的静止形态和接触角,计算结果和实验数据吻合得较好.和理论模型进行比较,分析了经典模型的适用范围.对于微槽道结构的壁面,计算给出不同方向测量得到的液滴接触角.实现了液滴在倾斜壁面上滑落过程的模拟.液滴沿斜面下滑时,前进角和后退角的变化存在周期性,这一周期性变化和表面粗糙结构密切相关. 相似文献
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随机波浪作用下近岸波流场的数值模拟 总被引:2,自引:0,他引:2
结合近岸波浪抛物型缓坡模型和近岸波流场模型,对近岸不规则波浪及其破碎后所产生的流场进行了数值模拟. 在不规则波浪场的模拟中,采用JONSWAP波浪谱对入射单向不规则波浪要素按等分频率法进行离散,应用考虑波浪不规则性和破碎效应的抛物型缓坡方程对波浪场进行数值模拟,并基于抛物型缓坡方程中的波浪势函数等参数计算波浪辐射应力,以波浪辐射应力为主要动力因素基于近岸流数学模型对近岸波浪破碎所产生的近岸流场进行数值模拟,并对数值模拟结果进行了验证. 模拟结果表明该模型可有效地用于研究波浪破碎产生的近岸波流场. 相似文献
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充气压力容器在超高速撞击下的典型损伤包括穿孔及其边缘的裂纹失稳破坏,会导致气体泄漏或爆炸,内压对容器前壁损伤的影响仍不明确。以不同内压的球形铝合金充气压力容器为研究对象,开展了球形铝合金弹丸超高速撞击实验和数值模拟计算,分析了内充气体压强对前壁穿孔形貌特征、穿孔直径、孔边环向应力等的影响规律和影响机理,讨论了气体冲击波的传播行为及影响前壁穿孔边缘裂纹失稳破坏的机制。结果表明:前壁穿孔边缘内翻边形貌与内压相关,内压越高,弯折程度越轻;穿孔直径与内充气体压强正相关,但气体对孔径的影响远小于容器壁厚及撞击速度的影响;穿孔边缘使裂纹失稳破坏的环向拉应力不仅受到后壁反射冲击波的影响,也与容器壁内应力波的传播有关,与内压成正比。 相似文献
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R. S. Maurya T. Sundararajan 《International Journal of Computational Fluid Dynamics》2013,27(5):391-400
The present work describes a numerical procedure to simulate the development of hydrodynamic entry region in a gravity-driven laminar liquid film flow over an inclined plane. It provides a better insight into the physics of developing film in entry region. A novel numerical approach is proposed which has the potential to provide solutions for the complex physics of liquid film spreading on solid walls. The method employs an incompressible flow algorithm to solve the governing equations, a PLIC-VOF method to capture the free surface evolution and a continuum surface force (CSF) model to include the effect of surface tension. To account for the moving contact line on the solid substrate, a precursor film model based wall treatment is implemented. Liquid film flow has been simulated for the Reynolds number range of 5 ≤ Re ≤ 37.5, and the predicted results are found to agree well with the available analytical and experimental data. 相似文献
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Some nonlinear dynamic properties of axisymmetric deformation are ex- amined for a spherical membrane composed of a transversely isotropic incompressible Rivlin-Saunders material. The membrane is subjected to periodic step loads at its inner and outer surfaces. A second-order nonlinear ordinary differential equation approximately describing radially symmetric motion of the membrane is obtained by setting the thick- ness of the spherical structure close to one. The qualitative properties of the solutions are discussed in detail. In particular, the conditions that control the nonlinear periodic oscillation of the spherical membrane are proposed. In certain cases, it is proved that the oscillating form of the spherical membrane would present a homoclinic orbit of type "∞", and the amplitude growth of the periodic oscillation is discontinuous. Numerical results are provided. 相似文献
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We perform computer simulations of using a micropipette to attach and then detach a red blood cell on a flat substrate mediated by receptor-ligand binding. The cell is initially swollen with osmotic pressure, coated with a specific kind of bio-molecular receptor, sucked into the micropipette and then allowed to approach a substrate coated with the corresponding ligand. Binding interactions between the membrane-bound receptors and the substrate-anchored ligands cause the cell to spread onto the substrate surface. While the specific interaction between a pair of receptor and ligand is described by a chemical reaction equation, a traction-separation law is adopted to describe the non-specific interactions between the receptors and the substrate. A surface diffusion model is introduced to describe the mobility of the receptors within the cell membrane. After the equilibrium state of adhesion is achieved, a pulling force is applied on the micropipette to detach the cell from the substrate. The governing equations of cell-substrate interactions and receptor diffusion are implemented in a finite element scheme to simulate the entire process of cell suction, cell spreading, receptor diffusion, and cell detachment, and to investigate the effects of membrane stiffness, cohesive parameters, micropipette size, and suction pressure on the unbinding kinetics of the cell. The simulation results are shown to agree qualitatively with existing experimental data. 相似文献
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In this paper, a method that can be used to model low Reynolds number incompressible flows with curved boundaries using SPH was presented. In contrast to that usually used for the flows with flat and straight boundaries, the hydrostatic pressure gradient is treated as a variable body force in this method, and thus, it can be applied to simulate the flows with curved boundaries. Three numerical examples of low Reynolds number incompressible flows, including Poiseuille flow, flow in a section of blood vessel with a local expansion, and flow between inclined plates were calculated to test the method. The results obtained with the proposed method were in good agreement with the analytical solutions. It implies that the method presented in this paper can be successfully used to simulate low Reynolds number incompressible flows not only with flat and straight boundaries but also with curved boundaries. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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The development of a theoretical model for the prediction of velocity and pressure drop for the flow of a viscous power law fluid through a bed packed with uniform spherical particles is presented. The model is developed by volume averaging the equation of motion. A porous microstructure model based on a cell model is used. Numerical solution of the resulting equation is effected using a penalty Galerkin finite element method. Experimental pressure drop values for dilute solutions of carboxymethylcellulose flowing in narrow tubes packed with uniformly sized spherical particles are compared to theoretical predictions over a range of operating conditions. Overall agreement between experimental and theoretical values is within 15%. The extra pressure drop due to the presence of the wall is incorporated directly into the model through the application of the no-slip boundary condition at the container wall. The extra pressure drop reaches a maximum of about 10% of the bed pressure drop without wall effect. The wall effect increases as the ratio of tube diameter to particle diameter decreases, as the Reynolds number decreases and as the power law index increases. 相似文献
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Front‐tracking by the level‐set and the volume penalization methods in a two‐phase microfluidic network 下载免费PDF全文
Two‐phase immiscible fluids in a two‐dimensional micro‐channels network are considered. The incompressible Stokes equations are used to describe the Newtonian fluid flow, while the Oldroyd‐B rheological model is used to capture the viscoelastic behavior. In order to perform numerical simulations in a complex geometry like a micro‐channels network, the volume penalization method is implemented. To follow the interface between the two fluids, the level‐set method is used, and the dynamics of the contact line is modeled by Cox law. Numerical results show the ability of the method to simulate two‐phase flows and to follow properly the contact line between the two immiscible fluids. Finally, simulations with realistic parameters are performed to show the difference when a Newtonian fluid is pushed by a viscoelastic fluid instead of a Newtonian one. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Summary The steady laminar flow of a viscous incompressible fluid through a two-dimensional channel, having fluid sucked or injected with different velocities through its uniformly porous parallel walls is considered. A solution for small suction Reynolds number has been given by the authors in a previous paper. The purpose of this paper is to present a solution valid for large Reynolds numbers for the cases of (i) suction at both walls, and (ii) suction at one wall and injection at the other. A technique of matching outer and inner expansions is used to obtain an asymptotic solution for both of these cases. Further a perturbation solution for the case of suction at one wall and injection at the other is obtained by choosing the difference between two wall velocities as the perturbation parameter. Both asymptotic and perturbation solutions are confirmed by exact numerical solutions. As expected, the resulting solutions show the presence of the usual suction boundary layers in both types of flow considered in this paper. 相似文献