Author(s): Ang Gao; Shiqiang Wu; Xiufeng Wu; Jiangyu Dai
Linked Author(s): Jiangyu Dai, Wu Shiqiang
Keywords: Shallow lakes Wind drag coefficient Wind-waves-flow mutual feedback mode
Abstract: Wind drag coefficient （Cd） is a key parameter in momentum flux at the water-air interface. Currently, the widely used parametric methods of Cd are mostly proposed based on the ocean situation, where the characteristics of ocean wave and current and their mutual-feed mechanism（MFM） are less affected by the wind blowing fetch (F) and water depth（d）, and Cd is mostly a function of wind speed（u）. Due to the limited range and water depth characteristics of Limited Waters（LW）, such as lakes and wetlands, the characteristics and MFM of wave and current are synthetically affected by u, F and d based on measured data. Therefore, the widely used " Cd -u " relation has limited adaptability in LW, and it is urgent to propose a suitable Parametric scheme for Cd in LM. Based on this, the dynamic process in the water-air boundary layer is analyzed, two dimensionless numbers, namely wind blowing fetch Froude number（FrF） and wind blowing fetch Reynolds number（ReD）, were innovatively constructed to characterize the combined action of water and air in LW. The paradigm scheme of Cd was proposed considering the comprehensive influence of u, F and d for the first time. Finally, the quantitative expression of Cd is obtained by fitting multiscale（i. e. flume, lakes, offshore and open sea） measured data. The results show that Cd is positively correlated with u and F, and negatively correlated with d. The proposed expression overcomes the limitation of traditional expression use in the LW, and maintains the overall consistency with the traditional expression.
Year: 2025