Experimental Study on Wind-Wave Momentum Flux in Strongly Forced Conditions

A quantitative description of wind-wave momentum transfer in high wind conditions is necessary for accurate wave models, storm and hurricane forecasting, and models that require atmosphere-ocean coupling such as circulation and mixed layer models. In this work, a static pressure probe mounted on a vertical wave follower to investigate relatively strong winds (U-10 up to 26.9 m s(-1) and U-10/C-p up to 16.6) above waves in laboratory conditions. The main goal of the paper is to quantify the effect of wave shape and airflow sheltering on the momentum transfer and wave growth. Primary results are formulated in terms of wind forcing and wave steepness ak, where a is wave amplitude and k is wave number. It is suggested that, within the studied range (ak up to 0.19), the airflow is best described by the nonseparated sheltering theory. Notably, a small amount of spray and breaking waves was present at the highest wind speeds; however, their effect on the momentum flux was not found to be significant within studied conditions.