| With the rapid development of nanotechnology and micro-nanoelectromechanicalsystems, fluid flows have attracted particular attention in nano-scale. Flowing velocityslippage has a very important influence on the micro and nano-scale liquid flow. Inclassical fluid mechanics, it is generally assumed that the velocity of relative motionbetween the fluid and the solid surfaces is zero. Namely there is no slippage on theliquid-solid interface. This is the traditional "no-slip boundary condition". In recent years,with the development of micro and nano-testing technology and its related fields ofscience and technology, this assumption is no longer valid in some cases. Sometimesboundary slippage is existed.The so-called boundary slippage refers to the phenomenon that fluid has a relativemotion to the solid surface. Studies show that in the micro and nano-scale problemsboundary slippage occur in some particular cases. So in what cases could the boundaryslippage happen? This paper denotes the state of between with and without boundaryslippage as the critical point, and the external force corresponding to this state as criticalforce. In this paper, different parameters of boundary slippage phenomena due to theliquid flow on the solid-liquid interface have been studied extensively. The relationshipbetween different parameters and boundary slippage is obtained, especially therelationship of different parameters with the critical point. Some molecular dynamicsimulations have been conducted for nano-scale flows. Influences of material parametersand flow pressure on the critical value of boundary slippage are analyzed. The results ofthe study show that the rule of liquid flow on the solid boundary is similar to that of solidsliding friction. Critical force is a function of pressure and material constants of fluid andsolid. That is F P, where F is the critical force to generate the boundary slippage,is the a function of material constant, P is the pressure near the boundary. |
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