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Abstract

Air sided flow profiles were measured in the linear wind-wave-facility of the Heidelberg Institute for Environmental Physics (IUP) to assess the wind-induced momentum transport to a water surface. Therefore, a recently developed technique of particle streak velocimetry (PSV) was used, which allows the time-resolved imaging of two-dimensional flow fields. This measurement technique, that uses the camera-imaging of particles seeded in the flow field, could thereby be tested and approved in another wind-wave-tunnel. From the flow fields, the mean total drag and its partition into turbulent and viscous shear stresses could be determined for different flow-conditions. From these, also the acting pressure forces were estimated. The measurements were made at three different fetches from 75 to 220 cm and four windspeeds each, ranging from about 1 to 6 m/s. The obtained stress-profiles match those of similar studies and furthermore allow the assessment of the influence of different fetches on the partitioning of the shear stress for the first time. During the evaluation problems occurred in the detection of particles in certain velocity-ranges. Their impact on the data could be minimized, but the problems could not be solved within the scope of this study.