Analysis of flow electrification in micro rough capillaries

In this paper we analyze some experiments made previously on streaming current in glass capillaries. As the "classic Poiseuille flow" and the hypothesis of smooth pipes do not seem to give a good agreement with the experiments, we have tried to see if a model taking into account the roughness of the tubes and a possible slip on the wall could give a better agreement. Indeed, for a liquid flowing inside a capillary of very small diameter, the non-slip hypothesis on the wall seems to be questionable. Experiments to determine the validity of such hypothesis are very difficult to develop and results are often not that clear, especially because of the large number of parameters. This was not our purpose, but just to see if the slip hypothesis combined with the effect of roughness could give a better model of the streaming current phenomenon in micro capillaries.