Molecular Dynamics Simulation On The Migration Behavior Of Liquid

Migration refers to the phenomenon that liquid moves on the solid surface under the action of temperature gradient and wettability gradient.When there is a temperature gradient on the surface,it will produce a non-uniform tangential stress on the surface of the liquid,which will cause the liquid to move from the hot end to the cold end.In a friction system,when two surfaces slide against each other,the heat generated by friction will produce a thermal gradient in the friction area,which may cause the liquid lubricant to migration from the high temperature area to the low temperature area.In addition,micro and nano electronic components are developing in the direction of high efficiency,miniaturization and high integration in recent years,but it brings the problems of high heat generation and high local temperature.Therefore,how to solve the heat generation problem of electronic components by means of liquid transportation is the key to the progress of micro and nano electronic technology.Liquid migration is a very complex and dynamic process,which often shows non-equilibrium and non-linear behavior in the process of creep.It is not enough to understand these phenomena only from the macroscopic point of view.In this paper,molecular dynamics is used to simulate the migration behavior of liquid,which is helpful to understand the migration mechanism from a microscopic point of view.Firstly,the migration of ionic droplets on graphene surface driven by temperature gradient is simulated and its mechanism is analyzed.The results show that the droplets move from the high temperature end to the low temperature end along the direction of temperature gradient.The droplet moves faster on the surface with larger temperature gradient,and the geometry of the droplet changes during the movement.The initial velocity of droplets is large on the surface with high temperature,and the average acceleration is also large on the surface with high temperature gradient.In terms of internal structure,due to the mutual attraction between the droplet and the solid surface,a dense adsorption layer appears at the bottom of the droplet.Secondly,The migration movement of water droplets on the surfaces with different temperature gradients and wettability was simulated,and the influence of the coupling of surface wettability and temperature gradients on the migration of water droplets was explored.The results show that water droplets move from high temperature region to low temperature region driven by different temperature gradients,and the migration rate of water droplets on graphene surface increases with the increase of temperature gradient.The migration motion of water droplets on different wettability surfaces was studied.It is found that when the water drops move on the surface with different wettability,a layer with high density will be formed at the bottom of the water drops,and on the surface with high wettability,the layer with high density will be formed.On the surface with high wettability and high temperature gradient,water droplets have a high initial migration speed,but also suffer from a large friction force in the migration process,resulting in a faster reduction of creep speed.Finally,The migration movement of water droplets on surfaces with different temperature gradients and stiffness was studied to explore the influence of stiffness on the migration movement of water droplets The results show that water droplets show different wettability on surfaces with different stiffness On the surface of graphene with larger stiffness,the driving force generated by amplitude gradient decreases because of the limitation of amplitude,so the movement speed of water drop on the surface with larger stiffness is smaller than that on the surface with smaller stiffnessIn this paper,the molecular dynamics simulation of the migration behavior of liquid was carried out,and the effects of surface temperature gradient and wettability on the migration behavior of liquid were analyzed.The research results have important theoretical and practical significance for understanding the mechanism of creep and realizing the regulation of liquid migration.