Report from Working Group on Deep Water Wave Kinematics: Fid-Bau Portal

Report from Working Group on Deep Water Wave Kinematics

Lambrakos, K. F. / Gudmestad, O. T.

Abstract There are presently many wave kinematics procedures that are used by the offshore engineer to calculate design kinematics. These procedures include the highly nonlinear, two-dimensional breaking wave methods, the linear, random three-dimensional methods and others. In many cases the application determines the procedure to be used, e.g. for steel piled jacket (SPJ) static design the Stokes type procedures have traditionally been used. In other instances, the choice of the procedure depends on regulatory agency requirements, familiarity, available experimental verification, and also simplicity. The argument can be made that all these procedures have served the offshore industry well since there have been no major offshore platform failures that are directly attributed to wave kinematics inaccuracies. This success, however, may be due to general conservative approaches used in platform design, and to compensating factors. All procedures represent approximations to the real offshore kinematics problem, and as design procedures become more sophisticated, aiming to improve safety while reducing platform costs, there is a two-fold need (1) for additional verification and improvement of the various available procedures and (2) for development of procedures that solve satisfactorily the general problem of three-dimensional irregular waves with currents. The additional verification and establishment of ranges of applicability of present procedures is of utmost importance since some of the procedures, e.g. stretching methods for irregular waves, give significantly different kinematics in the wave crest region.