排序方式: 共有99条查询结果,搜索用时 15 毫秒
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A highly efficient three-dimensional (31)) Lattice Boltzmann (LB) model for high-speed compressible flows is proposed. This model is developed from the original one by Kataoka and Tsutahara [Phys. Rev. E 69 (2004) 056702]. The convection term is discretized by the Non-oscillatory, containing No free parameters and Dissipative (NND) scheme, which effectively damps oscillations at discontinuities. To be more consistent with the kinetic theory of viscosity and to further improve the numerical stability, an additional dissipation term is introduced. Model parameters are chosen in such a way that the von Neumann stability criterion is satisfied. The new model is validated by well-known benchmarks, (i) Riemann problems, including the problem with Lax shock tube and a newly designed shock tube problem with high Mach number; (ii) reaction of shock wave on droplet or bubble. Good agreements are obtained between LB results and exact ones or previously reported solutions. The model is capable of simulating flows from subsonic to supersonic and capturing jumps resulted from shock waves. 相似文献
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利用分子动力学模拟方法对含纳米孔洞的单晶铁在冲击波压缩下的结构相变(由体心立方结构α到六角密排结构ε)进行了研究,单晶铁样品的尺寸为17.2nm×17.2nm×17.2nm,总原子数428341个,在样品的中央预置一个直径为1.12nm的孔洞,利用一活塞分别以350,500,1087m/s的速度撞击样品产生冲击波,对应的冲击波压缩应力分别为12,17,35GPa.撞击方向沿单晶铁的[100]晶向.计算结果表明,在冲击波压缩下,孔洞对铁中的相变起了诱导作用,伴随着孔洞的塌陷,相变首先出现在孔洞周围的(011)面和(011)面上,然后扩展到整个样品.通过分析冲击压缩下原子的位移历史,解释了相变的微观机制,发现孔洞周围的原子在{011}面上沿〈011〉晶向滑移,离孔洞中心距离越近的{011}面上的原子容易滑移,间隔一层的{011}面与相邻层原子的移动位移幅度不同,这种相对滑移导致出现了新的结构(hcp结构).
关键词:
相变
分子动力学
冲击波
纳米孔洞 相似文献
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液膜马达作为一种新颖的实验装置在基础研究和技术应用方面都将会发挥着重要的作用, 深入研究各种条件下液膜马达的电致流动特征是非常有意义的. 本文从理论上研究了均匀恒定外电场中的液膜马达在方波电泳电场驱动下的动力学特征, 解析地给出了液膜转动的线速度随时空变化的规律. 理论结果表明, 液膜会随着电泳电场频率的增大由对称性往复转动逐渐转变为振动, 这不仅有助于从理论上认识液膜马达振动的物理根源, 也为在实际应用中设计液膜搅拌机提供了一种新思路. 相似文献
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This work focuses on the characteristics of the Rayleigh-Taylor Instability (RTI) of the interfaces formed by two semi-infinitely distributed fluids and one interlayer. In consideration of the coupling effects between the interfaces, the expression of the growth rate is obtained. The result reveals that the instability growth rate depends on the density and thickness of the interlayer. It is found that /f the interlayer thickness is less than 0.6 times of the disturbing wavelength, the coupling effects should be considered. 相似文献
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利用加权本质上无振荡(WENO)方法模拟超声速流体Kelvin-Helmholtz(KH)不稳定性,研究速度梯度对KH不稳定性线性增长率和后期非线性演化的影响.模拟发现超声速流体中的速度梯度对KH不稳定性具有较强的致稳作用,给出了包含速度梯度致稳的线性增长率经验公式.数值模拟和经验公式符合得很好.模拟给出了清晰的流场密度等值线,这说明WENO方法模拟超声速流体KH不稳定性具有较好的界面变形捕捉能力.模拟结果表明速度梯度影响KH涡的演化,在给定密度梯度的情况下速度梯度越大KH涡的横向尺度越小.
关键词:
Kelvin-Helmholtz不稳定性
超声速流体
速度梯度 相似文献
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