Wave kinematics factor in real and simulated storms

This paper presents wave kinematics factors (F_S)¹ 1 Also known as wave spreading factor or kinematics reduction factor. for the storm data collected in the northern North Sea from three wave height altimeters mounted on a jacket platform. Directional wave spectra and spreading functions are computed from the surface elevation measurements of the storm data, from which wave kinematic factors are derived. The hybrid wave model of [Zhang, J., Yang, J., Wen, J., Prislin, I., Hong, K., 1999. Deterministic wave model for short-crested ocean waves. Part I. Theory and numerical scheme. Applied Ocean Research, 21, 167-188] is used to predict wave particle kinematics of the storm data and the predicted kinematics are also used to compute the wave kinematics factor. Experimental investigations have also been undertaken in a multidirectional wave basin, wherein the storms recorded at the platform are reproduced with a scale of 1:55. Wave elevations and wave particle velocities beneath the waves are measured in the wave basin for both long-crested and short-crested waves using arrays of wave probes and velocimeters and the measured wave kinematics are utilised to calculate the wave kinematics factor for the reproduced storms. The wave kinematic factors computed for the full-scale measurements compare well with the values for the reproduced storms in the wave basin. This investigation show that the wave kinematics factors vary with the spreading parameter s and for the northern North Sea the values, F_s=0.78 (s=2); F_s=0.85 (s=4); F_s=0.88 (s=6) and F_s=0.92 (s=8) are appropriate. © 2005 Elsevier Ltd. All rights reserved.