THE ROLE OF WIND WAVES ON THE FORMATION AND DEVELOPMENT OF LANGMUIR CIRCULATIONS IN A SHALLOW WATER REGION

摘要

The secondary circulations in wind-driven currents are well known as the Langmuir circulation. The Langmuir circulations in a shallow water region have been investigated experimentally in two cases where wind waves are fully developed and their generation is suppressed by adding surfactant into the working fluid. The results of flow visualization reveal that the Langmuir circulations can be formed independently of the development of wind waves, and that their final steady spacing does not depend on the parameters of wind waves or surface fluctuations but only on the mean water depth. However, the results of the flow visualization and the velocity measurements give the conclusion that the development of wind waves causes the Langmuir circulations to be more stable and stronger. These experimental results imply that they can be formed without the interaction between the wind-driven currents and wind waves.