Particle tracking velocimetry beneath water waves. part II : water waves

Particle Tracking techniques described earlier in the first part of this paper (Hering et al. 1997) were used to study the flow field beneath mechanically generated and wind induced flow fields. Experiments were conducted at three different wind/wave facilities (Heidelberg, Delft and San Diego). Particle Tracking allows an extensive study of drift velocities, wave orbital motion and turbulent Reynolds Stress beneath water waves. Monte Carlo simulations show, that the effects of the moving water surface on the calculation of mean properties of a flow can easily be avoided by Lagrangian measurements. Due to micro-scale wave breaking friction velocity profiles show a significant increase of turbulence towards the interface.