抄録
The dilute addition of natural foods such as fermented soy-beans, grated yams and a kind of seaweeds to water flow within a circular pipe is newly recognized to control turbulent flow and to be effective for the degradation of frictional loss of the pipe flow. It should be noted that these natural foods are harmless to the environment. These additives show the degradation of the frictional loss of pipe flow as same as the usual artificially-synthetic additives, which are generally harmful to the environment. The net-structure of natural foods in pipe flow is iced instantaneously using liquidized nitrogen and is visualized by using optical and electronic microscopes. As the results the degradation effect of frictional loss of pipe flow is newly made clear to be caused by the control of turbulent flow near the pipe wall.
