Mechanistic, empirical and numerical perspectives on wind-waves interaction

Abstract: A mechanistic theory of wind-wave interaction must rely on verifiable assumptions and offer reproducible observable predictions. For decades, the limited mechanistic grasp on the problem has motivated RANS and LES modeling and has driven a vast empirical effort to describe the interaction in terms of wave-induced modifications of standard statistical characteristics of the wind, such as wind profile, kinetic energy balance or exchange coefficients. Because the mechanistic, empirical and numerical approaches are all concerned with the same phenomenon occurring in the same media, consistency here requires that the assumptions on which the approaches rest and the predictions they generate are compatible with each other and supported by measurements. Recent findings from theoretical analysis and field experiments advanced the understanding of the statistical and dynamic patterns of the wave-coherent flow, which is at the core of the mechanistic description of the wind-wave exchange. The progress prompts reexamining of earlier concepts, efforts and findings to evaluate their suitability, validity and usefulness. For the purpose, this survey traces the development of ideas, methods and results in the study of the wind wave generation.