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旋涡动力学方程非定常动边界条件 总被引:3,自引:2,他引:3
详细讨论了旋涡动力学方程非定常动边界条件。给出了任意非定常运动边界上速度旋度的确定方法。并采用了“局部线性化及再校正”技术、时间滞后求解方法,求解每一时间步边界上速度旋度值。这样可以很大程度上节省计算时间。并讨论了数值实验结果,指出动边界问题的非线性特征,对这样复杂的非线性问题不宜作过份简化。 相似文献
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液固两相流中流体旋涡对固体粒子运动影响的数值研究 总被引:9,自引:0,他引:9
基于离散涡方法求得的非定常、不稳定流场和颗粒的Lagrangian运动方程,数值计算了四种St数下的泥沙粒子在圆柱绕流场中的运动。计算结果证明了颗粒运动与流体旋涡存在着明确的相关结构:在钝体(圆柱)表面附着泥沙,当流体流过钝体时产生具有剧烈分离的不稳定流动,带动钝体表面泥沙起浮。对于小St数(0.15~0.59)与中等St数(1.33~2.36)的泥沙颗粒被流体旋涡所带起,井被卷入流体旋涡结构内,被卷入流体旋涡结构内的泥沙颗粒在运动过程中始终分布于旋涡区,即在旋涡区聚集。 相似文献
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Flow behavior of the driven two-dimensional vortex lattice is numerically studied with different densities of randomly distributed pointlike pinning centers. Different features in the curves of velocity-force dependence are found between the elastic and plastic regimes. Scaling fit between force and velocity above the critical driving force can be obtained in the elastic regime but fails in the plastic regime. Transition from the lastic to plastic regimes is accompanied by maximum peaks in the differential curves of velocity-force dependence in the disordered vortex lattice. 相似文献
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The thermodynamics of the vortex lattice of high-temperature superconductors has been studied by solving the generalized Ginzburg-Landau equations derived microscopically. Our numerical simulation indicates that the structure of the vortex lattice is oblique at the temperature far away from the transition temperature Tc, where the mixed s-dx2-y2 state is expected to have the lowest energy. Whereas, very close to Tc, the dx2-y2 wave is slightly lower energetically, and a triangular vortex lattice recovers. The coexistence and the coupling between the s and d waves would account for the unusual dynamic behaviours such as the upward curvature of the upper critical field curve HC2(T), as observed in dc magnetization measurements on single-crystal YBa2Cu3O7 samples. 相似文献
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动电学效应对微通道内流体流动特性影响很大,其对通道内粒子分布特性的影响使得通道近壁面流体流动特性极不稳定。本文采用分子动力学方法模拟了二维矩形微通道内NaCl稀电解质溶液的流动特性,考虑存在于不同粒子间的Lennard-Jones势能、静电力、以及带电离子与水分子间的相互作用,得到了粒子在通道内的分布特征。结果显示在动电学效应主要作用于通道壁面附近,而主流区域影响极小。Na~+离子在无量纲通道高度达到0.08和0.91时其浓度达到最大值,沿远离壁面其浓度逐渐降低,与壁面电性相反的Cl~-离子则在无量纲通道高度达到0.15和0.84附近浓度最高。其结果与基于连续介质解理论的Boltzamnn统计分布一致。水分子的浓度在壁面附近也较通道中心处高。 相似文献
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概述了二维流体力学程序YGX等在银河-1和银河-2巨型计算机上的向量化和并行化工作,总结了一些具有一般意义的实际经验,给出了程序在计算机上执行所获得的重要测试数据。 相似文献
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THE INFLUENCE OF GRAIN SIZE AND TEMPERATURE ON THE MECHANICAL DEFORMATION OF NANOCRYSTALLINE MATERIALS: MOLECULAR DYNAMICS SIMULATION 总被引:2,自引:0,他引:2 下载免费PDF全文
Nanocrystalline (nc) materials are characterized by a typical grain size of 1-100nm. The uniaxial tensile deformation of computer-generated nc samples, with several average grain sizes ranging from 5.38 to 1.79nm, is simulated by using molecular dynamics with the Finnis-Sinclair potential. The influence of grain size and temperature on the mechanical deformation is studied in this paper. The simulated nc samples show a reverse Hall-Petch effect. Grain boundary sliding and motion, as well as grain rotation are mainly responsible for the plastic deformation. At low temperatures, partial dislocation activities play a minor role during the deformation. This role begins to occur at the strain of 5%, and is progressively remarkable with increasing average grain size. However, at elevated temperatures no dislocation activity is detected, and the diffusion of grain boundaries may come into play. 相似文献
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高温超导体相对定量的磁通钉扎力分析 总被引:1,自引:0,他引:1
为了更准确地分析高温超导体在高温如液氮温区的磁通钉扎机制,基于Dew—Hughes模型,对传统的钉扎力标度方法进行了改进,发展了钉扎力密度的多源分析方法.在高温超导体中芯钉扎机制处于主导地位,由正常相和Ginzburg参量(△k)变化引起的点、面和体缺陷在改进分析方法中均将考虑.论中通过几个Bi-2223/Ag带材的钉扎力分析实例对传统的单函数方法和改进多源分析方法进行了比较.结果表明,采用多源分析方法可以更准确地给出样品中起作用的钉扎机制的信息,例如,样品中对磁通钉扎有贡献钉扎中心类型及其相对强度等. 相似文献
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