VARIATIONS IN THE CREST KINEMATICS OF WAVE GROUPS

Accurate measurements of the kinematics under wave crests in uni-direc tional, one and two component wave groups in a flume have produced the following conclusions: The wave group length affects the internal wav e kinematics. Waves in shorter wave groups can produce higher wave kin ematics above still water level than similar waves in longer groups. R egular waves can be accurately modelled using a higher order regular w ave Fourier theory provided Stokes' second definition of wave celerity is used. Steep, near-breaking two-component waves can be modelled acc urately using a derivative of linear theory, here superposition stretc hing. Measurements should be made above mean water level, if experimen tal results are to have much credence.