流体力学に関する誤情報の拡散

（上流域と下流域における曲がる川の比較）

抄録

Elementary school textbooks say that in a curved river, the flow is slow on the inside and fast on the outside. On the other hand, from a fluid-dynamic point of view, the inside is fast and the outside is slow. We have investigated why such a contradiction occurs. Previous measurements in downstream rivers have confirmed that sedimentation occurs inside bends in plain rivers, and many rivers slow inside. In this report, measurements were taken in the upstream river. As a result, we observed several cases in which the inner part was faster and the outer part was slower in the upper reaches. Further experiments are needed to confirm this result. In addition, since most people usually see rivers in the lower reaches, it is speculated that elementary school textbooks have described that the inside of the river is slow.