Fluid dynamics simulation assumptions

P 11] Simulations were carried with a simplified chamber and air-bubble pocket geometry. Details on this geometry and the several assumptions taken for describing the fluid dynamics can be found in [23] and are not described further here. Generally, the experimental known fluid dynamic features were taken into account, e.g. the convective motion based on vortices was assumed also in the model. 

Although it turned out that a number of essential features concerning dynamics of molecular liquids can be well captured by the theory of the previous subsection (see Secs. 3 and 5), an intense investigation through experimental, theoretical, and molecular-dynamics simulation studies for simple liquids has revealed that the microscopic processes underlying various time-dependent phenomena cannot be fully accounted for by a simplified memory-function approach [18, 19, 20]. In particular, the assumption that the decay of memory kernels is ruled by a simple exponential-type relaxation must be significantly revised in view of the results of the kinetic framework developed for dense liquids (see Sec. 5.1.4). This motivated us to further improve the theory for dynamics of polyatomic fluids. 

Traditional non-slip assumptions have been doubted for a long time in microfluidic systems. Recently, the results from molecular dynamics simulations and experiments on micro- and nanoscales strongly indicate the existence of slip flow. Theoretically, fluids will slip when the attraction between fluids molecules is stronger than the wall/fluid molecule attraction. The amount of slip is descrihed as the slip length which is the notional distance inside the surface at which the velocity equals to zero (Fig. 6a). 

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