In the present paper experimental generated Freak Waves are investigated as they are defined as transient waves existing in one certain location in one definite instant in time (Kaldenhoff & Schlurmann, 1999). Freak Waves occur due to superposition of numerous wave components of a real sea state and are typically characterized by an extreme waveheight. Moreover, it is determined that Freak Waves are sometimes identified by spilling breaking (Schlurmann, 1999 or Kway et al., 1998). The characteristics of Freak Waves were investigated in spatial domain. Interestingly, laboratory generated waves with extreme waveheights show significant similarities to results from field observations from real sea states, e.g. observed by Sand et al. (1989), Yasuda et al. (1997) or Rozario et al. (1993). Furthermore, a state-of-the-art stereo-PIV system is used to analyse the flow phenomena underneath a transient wave at the very moment of breaking. Since velocities and accelerations can be recorded in the wave field particle image velocimetry can give important hints to new aspects in analysing the dynamics of Freak Waves. However, evaluations of flow fields using this technique are an immense improvement in hydrodynamics, but further studies have to be carried out.
Freak Waves are defined as transient waves existing in one specific location in one particular instant in time. These extreme waves occur most often in deep water environment due to the superposition of numerous dispersive wave components within an irregular sea state. Highly complex nonlinear wave-wave interaction processes inside the spectrum take place and reinforce the focussing of a Freak Wave. Under these conditions a Freak Wave is characterized by an enormous waveheight and strong velocities underneath the crest of the wave (KUhnlein, 1997). It is further known that other effects enhance the occurence of Freak Waves - strong
