A piston-cylinder apparatus was established to measure the solubility and diffusivity of air in dimethyl silicone oils and in hydraulic oils based on the PVT state equation of air and the solution of unsteady one-dimensional diffusion equation.The measured diffusivity-temperature relation can be well fitted by the Arrhenius equation for engineering applications.The correlation between the solute diffusivity D and solvent viscosity μ is examined.In terms of Eyring＇s activation theory,the activation in the air-silicone-oil diffusion process is quite different from that in the momentum transport of the silicone oil：the activation entropy of the former is positive while that of latter is negative.However,the activation enthalpies of the two processes are in the same order of magnitude,which leads to the observation that Dμ/T is roughly constant.
A semi-empirical spectrum model is proposed to describe the experimental data of the steady shear properties of a Shengli waxy crude oil near its gel point, where sophisticated structural effects become apparent due to the existence of waxy crystals in the crude oil. The model, consisting of a time spectrum, can well fit the steady shear viscosities of the waxy crude oil over the whole experimental shear rate region from 10-4 to 102 s- 1. Two other experiments on complex fluids reported recently in the literature are also well described by this model demonstrating the applicability and accuracy of the model.
With the development of analytical instrumentation to minimization,integration and automation,the microfluidic chips,which are more integrated,complex and diversified,have been applied widely on the manufacturing of analytical instrumentation.However,the present photolithography-based microfabrication technology,which is only able to pattern microchannels with simple inside structures,can not follow the rapid development of requirements.For solving the problem,a fabrication method based on the restricting effect of laminar flow is proposed for the micro etching on isotropic substrates.Experiments were conducted inside glass-based microchannels,in which certain etchant was used to form complicated microstructures.The flow parameters＇ effects on the aspect ratio,side wall profile and etching rate were revealed by the experiments.The experimental results reveal that the topography of micro structures patterned with the restricted flow etching method is mainly determined by the flowrates of separator and etchant.The computational fluid dynamics（CFD） model on the interface between multiple streams was established for the etching process,and analysis on the causes of various micro topographies was conducted based on the CFD simulation results.The experimental data consisted with the simulation results very well.The investigation depicted in this paper indicate that the flow restricted etching method provides sufficient references for the research and understanding on the mass transport at the liquid-liquid surface in the microchannel and can be used to pattern complex micro structures with high aspect ratios,meantime,it greatly enriches the microfabrication technology for microfluidic chips.
