Nanoscale Poiseuille flow and effects of modified Lennard–Jones potential function
Nanoscale Poiseuille flow and effects of modified Lennard–Jones potential function
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DOI：
10.1007/s00231-010-0624-4
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发表时间：
2010-06
影响因子：
2.2
通讯作者：
D. Toghraie Semiromi;A. Azimian
中科院分区：
文献类型：
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作者：
D. Toghraie Semiromi;A. Azimian
采用非平衡分子动力学模拟(NEMD)方法对纳米流道中液态Ar的Poiseuille流动进行了数值模拟。纳米通道为三维矩形棱柱几何结构，在102、108和120℃时，所涉及的Ar原子数目分别为2,700、2,550和2,400。在模拟过程中，沿着流动方向施加从1到11 Pn(皮科牛顿)的外部驱动力来进口流体颗粒。为了在通道上获得更均匀的温度分布，使用了靠近壁面的局部恒温器。此外，通过比较108K和133K外力作用下液固界面附近的密度分布，考察了其他混合规则(Lorenthz-Berthelot和Waldman-Kugler规则)对界面结构的影响。与Lorenthz-Berthelot规则相比，使用Kong和Waldman-Kugler规则时，固体壁附近的分子分布更加随机。这意味着使用孔氏规则和Waldman-Kugler规则而不是Lorenthz-Berthelot规则减弱了固体-流体原子之间的引力。计算结果还表明，平均轴向速度在流道中心线附近呈对称分布，增加外力可以提高流体的最大速度值和平均速度值。此外，滑移长度和滑移速度是驱动力的函数，随着进口驱动力的增大，滑移长度和滑移速度呈上升趋势，在很低的外力(<；1×Pn)下不满足滑移边界条件。
Numerical simulation of Poiseuille flow of liquid Argon in a nanochannel using the non-equilibrium molecular dynamics simulation (NEMD) is performed. The nanochannel is a three-dimensional rectangular prism geometry where the concerned numbers of Argon atoms are 2,700, 2,550 and 2,400 at 102, 108 and 120 K. Poiseuille flow is simulated by embedding the fluid particles in a uniform force field. An external driving force, ranging from 1 to 11 PN (Pico Newton), is applied along the flow direction to inlet fluid particles during the simulation. To obtain a more uniform temperature distribution across the channel, local thermostating near the wall are used. Also, the effect of other mixing rules (Lorenthz–Berthelot and Waldman–Kugler rules) on the interface structure are examined by comparing the density profiles near the liquid/solid interfaces for wall temperatures 108 and 133 K for an external force of 7 PN. Using Kong and Waldman–Kugler rules, the molecules near the solid walls were more randomly distributed compared to Lorenthz–Berthelot rule. These mean that the attraction between solid–fluid atoms was weakened by using Kong rule and Waldman–Kugler rule rather than the Lorenthz–Berthelot rule. Also, results show that the mean axial velocity has symmetrical distribution near the channel centerline and an increase in external driving force can increase maximum and average velocity values of fluid. Furthermore, the slip length and slip velocity are functions of the driving forces and they show an arising trend with an increase in inlet driving force and no slip boundary condition is satisfied at very low external force (<1 PN).