Etude expérimentale du coefficient de frottement d'écoulements laminaires en microtubes

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We highlight an original method to determine precisely the friction factor of laminar flows in capillaries. The experiments are performed at Reynolds numbers ranging from 10 to 1000 using a transient method. We carry out a set of experiments and develop a specific treatment method. The friction factor obtained for capillary diameters ranging from 50 to 530 µm is experimentally determined. Experiments are also developed for two fluids : distilled and tap water. Experimental results for tap water and fused silica surfaces indicate a deviation to the Moody's theory. An increase of the friction factor is observed for decreasing diameters using tap water. This result seems to be to due to the fluid's ionic composition (Electrical Double layer).