Liquid flow in smooth capillary pipes

Glass capillaries with diameters of d is an element of {280.6, 327.8, 857, 898, 1269} mu m and Re is an element of ]200, 3300[ were used to experimental study of the characteristics of frictional resistances of water flow in microtubes. It has been found that the entrance and end effects may be fully eliminated and the capillary diameters may be indirectly but accurately computed using the Hagen-Poiseuille law. This important computing may be done at nearly full laminar regime (Re <= 1900) without limitations (Re <= 400) reported in some references. It was confirmed experimentally that laminar, transitional and turbulent microflows are consistent with macroflows.