Abstract
Pressure drops were measured in this study because flow properties of water and several types of surfactant solutions in capillary flows were investigated. Generally, the smaller capillary diameter was, the smaller Reynolds number was. However, even though Reynolds number was smaller, shear rate was much greater than that of macro-sized pipe. Thus, the present study paid attention to the range from laminar region to transition one. Good agreements between micro-sized pipe flows and macro-sized ones were obtained for water flows. For surfactant solutions, similar flow properties were found independing on the molar concentration ratio. Moreover, laminarization was observed in comparison with water results. In explaining this behavior, relationship between flow properties and viscosity curve was discussed, and it is suggested that non-Newtonian property is contributing factor.