Development of the sea-surface bursting layer model for microscopic evaluation of wind wave breaker effects on currents

利用双层斜底风浪水池和计算机控制造波机，对波浪破碎和气流分离作用下风向水流的动量传递过程和水面下强湍动突增边界层的湍流结构进行了实验研究。得到的主要结果如下：1)PIV和LDV测量结果表明，在近地表区域，破碎波产生了具有强烈湍流动能和雷诺应力的爆发边界层。2)风生流作用下，爆发层的湍流动能超过切变流边界层的10倍左右。突发层内的湍流分量将作用于水面的风应力和破碎器应力的约30%传递到水深约为H_1/3&GT的7倍水深；3)采用VOF方法和κ-ε模型进行数值模拟，结果表明，线性代数雷诺应力模型适用于除掺气孔前以外的波浪破碎过程。4)风应力和破碎应力驱动的水面流速度与风速成正比，但与破碎的发生无关。5)突破层内的湍动能和涡粘性系数显著高于无破碎的风浪下的普通湍流边界层。

Experimental investigations using a wind-wave tank with a double deck, a sloping bottom and a computer-controlled wavemaker were made on the processes of momentum transfer from winds to currents through breaking waves and the turbulent structure of a bursting boundary layer with strong turbulence underneath water surface affected by wave breaking and air-flow separation. The obtained primary results are summarized as follows :1) Measurements using PIV and LDV demonstrated that the bursting boundary layer retaining the intensive turbulent kinetic energy and Reynolds stress is generated in near-surface area by breaking waves.2) The turbulent kinetic energy of the bursting layer exceeds about ten times of that of shear flow boundary layer caused by wind-induced current. The turbulent flow components within the bursting layer transmit about 30% of wind and breaker stresses acting on water surface to the water depth of about 7 times of H_<1/3>.3) A numerical simulation using the VOF method and the κ-ε model showed that the algebraic linear Reynolds stress model is applicable to the wave breaking processes except for the aerated bore front.4) The velocity of water surface currents driven by wind and breaker stresses is proportional to the wind speed but is independent of the occurrence of wave breaking.5) The values of turbulent kinetic energy and eddy viscosity coefficient within the bursting layer remarkably exceed those in the ordinary turbulent boundary layers underneath wind waves without breakers.