Experimental Study on Transitional Flow in a Circular Microtube

We investigate the characteristics of the transition from laminar to turbulent flow in the microtube with a diameter of 310μm. The microscopic particle image velocimetry is used to measure the water flow at Re=1600--2500 in the microtube. It is found that the flow transition occurs at Re=1600--1900, and the streamwise streaks and vortices appear in the transitional flow fields. These experimental observations provide a validation for the theoretical prediction of unstable travelling waves in pipe flow.