抄録
The present paper reviews a history of turbulence research in Hydraulics and Fluid Mechanics. In particular, the recent research of coherent structures are addressed, which are the most essential and important phenomena in wall turbulence such as boundary layers and open channels, as well as in free turbulence such as mixing layers, jets and wakes, because the coherent vortices generate turbulence from mean-flow energy and because they govern various transport phenomena such as momentum, energy, heat and mass. Although these researches have been intensively conducted in only the last twenty years, it is emphasized here that Leonardo da Vinci (1452-1519) was the first researcher in the world to observe coherent vortices, i. e. hairpin vortex, in water flows. Very recent refined experiments and numerical supercomputer simulations of coherent structures such as bursting phenomena are reviewed. Lastly, the prospective research toward the 21st century is proposed. The necessity of international research project of “Geophysical Large-scale Turbulence (GLT)” is stressed to clarify the global changes of environment in water and atmospheric spheres, such as various natural disasters, warmings due to CO2 greenhouse effect and acid rains.
