On Wave Kinematics Approximate Methods
May 6, 1991
Three common approximate methods known as Wheeler stretching, linear and vertical extrapolation are investigated to evaluate their application for predicting wave kinematics. The measured horizontal velocity of regular and dual component waves, which conceptual1y represent a very narrow and broad bandwidth wave train respectively, is found to be satisfactorily consistent with numerical results based on the finite-amplitude wave theory. Both numerical results and measurements are compared with the predictions of the three methods, and this comparison indicates that the prediction accuracy of each approximate method depends upon the bandwidth of the wave spectrum. Wheeler stretching better predicts wave kinematics for a broad bandwidth spectrum and 1inear extrapol ation is the better predictor for a narrow bandwidth spectrum.