Study on the viscosity of the liquid flowing in microgeometry

While micro-fabrication technologies are under extensive exploitation to fu lly realize the applications of micromachines etc, until the present time t he basic mechanisms governing the underlying fundamental principles of thes e micro- and nano-scale systems have not been fully understood. As the char acteristic dimensions of these devices approach micro- and nano-scales, att empts to understand the working phenomena pose great challenges. Under such situations, the commonly applied theories in continuum mechanics often bec ome limiting cases or even completely unsuitable. For example, one of the c ommonly used properties, viscosity, seems to play an important role in char acterizing the behavior of these micro- or nano-scale devices. In this pape r, a theoretical study, employing a molecular theory to investigate the eff ects of the geometrical dimensions on the viscosity and flow characteristic s for polar and non-polar liquids will be presented. The results indicate t hat the effects of the geometrical dimensions on the viscosity of liquids b ecome significant as the dimensions approach the micro- or nano-scale, and these effects are more significant in polar than in non-polar fluids.