纳米尺度圆柱绕流现象的分子动力学模拟研究

本文采用分子动力学模拟方法,利用Lennard-Jones(L-J)势能模型,模拟了Re为28时Ar流体流过Pt纳米圆柱的绕流现象.采用小步长时均值作为涡的瞬时值的方法,在纳米尺度、纳秒量级下得到了涡的周期性产生、组合、发展和脱落现象;在大步长时均条件下,得到了稳定的对称涡,表现出了绕流现象在不同时间范围内的不同特征.绕流过程还体现了流体的密度变化,圆柱上游密度大于下游密度、对称的两侧离轴线越远密度越大.结果表明,分子动力学模拟方法可以有效地细节刻画圆柱绕流现象.

MOLECULAR DYNAMICS SIMULATION STUDY ON FLOW AROUND A CIRCULAR CYLINDER IN NANOSCALE

Molecular dynamics simulation methods were carried out in this paper to study the flow of fluid(Ar)around a nano-circular cylinder(Pt)at a low Reynolds number(Re=8)with the Lennard- Jones(L-J)potential model.The periodic flow field was obtained by averaging streamlines within a small time scale.The common characteristics of the emergence,combination,periodic shedding and oscillation of vortices were observed from the profiles of the streamlines in nanoscale.The large time-averaged streamline forms the steady symmetric vortex.The results show that the flow indicates different characteristics in different timescales.The density profiles show that the fluid density in the upstream region is larger than that in the downstream region and the fluids become denser when it is farther from the symmetric axis.The paper also indicates that the flow phenomena can be described in details with molecular dynamics simulation methods.