富勒烯纳米流体在石墨烯纳米孔隙中的流动特性研究

发布时间：2018-01-07 12:16

本文关键词：富勒烯纳米流体在石墨烯纳米孔隙中的流动特性研究　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着微纳米技术与材料科学技术的迅速发展,纳米流体器件逐渐兴起,流体在纳米孔隙中的流动问题倍受关注。本文采用经典分子动力学方法,研究了富勒烯纳米流体在石墨烯纳米孔隙中的流动特性,并探索了富勒烯分子在石墨烯纳米孔隙内的传输特性。研究结果将对纳米流体在石墨烯孔隙中流动行为的认识以及石墨烯-纳米流体器件的设计提供一定的理论基础。对富勒烯纳米流体在石墨烯纳米孔隙中的Couette流动和Poiseuille流动特性进行了研究,探索了剪切速率、驱动外力、富勒烯体积分数、电场强度以及纳米孔隙宽度对边界滑移的影响。结果表明:边界滑移速率随着富勒烯体积分数的增加而增大。与此同时,当电场强度较小时,纳米流体的流动表现为边界正滑移,此时边界滑移速率随着电场强度的增强而减小;然而当电场强度达到临界值时,纳米流体的流动开始出现边界负滑移,此后边界滑移速率随着电场强度的增强先减小后增大。此外,在Couette流动中,当剪切应变率超过临界剪切应变率时,边界滑移速率迅速增大,并且临界剪切应变率随着电场强度的增强而增大;边界滑移速率随着纳米孔隙宽度的增大而减小。在Poiseuille流动中,随着驱动外力与纳米孔隙宽度的增大,纳米流体的流速增大,导致边界滑移速率增大。基于富勒烯纳米流体与石墨烯组成的Couette流动模型,探索了剪切速率、富勒烯体积分数以及电场强度对纳米流体粘度的影响。结果表明:富勒烯纳米流体的粘度与剪切应变率无关,却随着富勒烯体积分数的增加而增大。此外,当电场强度较小时,纳米流体的粘度随着电场强度的增强而增大;但是当电场强度达到临界值时,此后纳米流体的粘度随着电场强度的增强先减小后增大。基于富勒烯纳米流体与石墨烯组成的Poiseuille流动模型,对富勒烯分子的运动行为以及分布进行了探索。结果表明:当驱动外力与纳米孔隙宽度较小时,富勒烯分子团簇现象较明显,随着驱动外力与纳米孔隙宽度的增大,富勒烯分子团簇现象逐渐减弱,分子团个数逐渐增多;并且随着富勒烯体积分数的增加,富勒烯分子更容易发生团簇。与此同时,当电场强度较小时,随着电场强度的增强,富勒烯分子团簇现象逐渐减弱,并且富勒烯分子逐渐有向壁面运动的趋势,从而导致富勒烯分子团会在石墨烯壁面附近运动;然而当电场强度较大时,随着电场强度的增强,富勒烯分子会再次在通道中心附近运动并发生团簇现象。此外,研究还发现流动系统中富勒烯分子的总旋转动能只与富勒烯分子的个数有关,而驱动外力以及电场强度不会对其产生明显影响。
[Abstract]:With the rapid development of nanotechnology and materials science and technology, nano fluidic devices gradually rise, fluid flow problems in the pores have attracted much attention. This paper uses classical molecular dynamics method, the flow characteristics of fullerenes in fluid in the pores of Shi Moxi, and to explore the transmission characteristics of the fullerene molecules in graphene nano pore. The research results will provide a theoretical basis on the flow behavior of nanofluids in graphene pores in understanding as well as the graphene nano fluid device design. Flow characteristics of fullerenes in graphene nano pore fluid flow in Couette and Poiseuille were studied, explored the shear rate, driving force, fullerene volume fraction. Effect of electric field strength and nano pore width of boundary slip. The results show that the boundary slip rate with volume fraction of fullerene The number increasing. At the same time, when the electric field is small, the flow performance of nanofluids for boundary slip, the boundary slip rate with the increase of electric field strength decreases; however, when the electric field reaches a critical value, the nano fluid flow appeared negative slip boundary, then the boundary slip rate with the increase of electric field strength first decreases and then increases. In addition, the Couette flow, when the shear strain rate exceeds the critical shear strain rate, boundary slip rate increases rapidly, and the critical shear strain rate increases with the increase of electric field strength; the boundary slip rate decreases with the increase of nano pore width. In Poiseuille flow, with the increase of driving force with nanometer pore width, nano fluid velocity increases, resulting in the boundary slip rate increases. The fullerene and graphene nano fluid composition based on Couette flow The dynamic model of the shear rate, effects of fullerene volume fraction and electric field strength on the nano fluid viscosity. The results show that the fullerene nano fluid independent of viscosity and shear strain rate, but increases with the volume fraction of the fullerene. In addition, when the electric field is small, the nano fluid viscosity increases with the increase of electric field strength; but when the electric field reaches a critical value, then the nano fluid viscosity with increasing electric field strength decreased and then increased. The Poiseuille flow model of fullerene nano fluid Shi Moxi and composition based on fullerene molecular motion behavior and distribution are explored. The results show that when the driving force and the nano pore width is small, fullerene molecules the cluster phenomenon is obvious, with the increase of driving force and the nano pore width, fullerene cluster phenomenon gradually weakened, clusters The number gradually increased; with the increase of the volume fraction of fullerenes and fullerene molecules, are more prone to cluster. At the same time, when the electric field is small, with the increase of electric field strength, fullerene cluster phenomenon gradually weakened, and gradually a fullerene molecule wall movement trend, leading group will exercise in the vicinity of fullerene molecules of graphite vinyl wall; however, when the electric field is large, with the increase of electric field strength, fullerene molecules will again move near channel center and cluster phenomenon. In addition, the study also found that the number of the total rotational kinetic energy of fullerene molecules in flow system only with fullerene molecules, and the driving force and the electric field strength is not obvious the influence to it.

【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.71;TB383.1

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