Prediction for Irregular Ocean Wave and Floating Body Motion by Regularization: Part 1. Irregular Wave Prediction

Abstract

SummaryOcean waves can be explained in terms of many factors, including wave spectrum, which has the characteristics of wave height and periodicity, directional spreading function, which has a directional property, and random phase, which randomly represents a certain property. Under the assumption of a linear system, ocean waves show irregular behaviours, which can be observed in the forms of wave spectrum, directional spreading function, and complex phase calculations using the method of linear superposition. Ocean waves, which include a variety of periodic elements, exhibit direct proportionality between their period and propagation velocity. The purpose of this study was to understand the phase components of the period and to make exact calculations on the deterministic phase in order to make predictions on ocean waves. However, measurements of actual ocean waves exist only in the form of information on wave elevation, so we faced an inverse problem of having to analyse this information and calculate the deterministic phase. Regularization was used as part of the solution, and various methods were used to obtain stable values.

Short-time deterministic prediction of individual waves based on space-time X-band Marine radar measurements

“…There are many functional models in the literature to represent the directional spreading of the sea surface. Here, we adopt a normal frequency independent spreading function: 9…”

“…A remained practical issue is to determine the minimum requisite wave data for the phase-resolved wave prediction at the desired location for a desired duration (e.g. to obtain a short-time deterministic forecast of waves around a vessel 9 allowing for maneuvering and active control of the vessel). The associated theoretical problem is to find the spatial-temporal domain inside which the phase-resolved irregular wave motion can be accurately predicted for the given wave data.…”

Real-Time Simulation of a Rescue Ship Maneuvering in Short-Crested Irregular Waves

“…The significant wave height is H s = 5.0 m, corresponding to the sea state 6, and the wave elevation ζ generated by using the existing MPM spectrum is similar to that in Figure 9. Wave conditions in this sea area in rough weather can be measured by wave height meters or an x-band radar [42], which has not been carried out yet in this study. The frame rate is 20 Frames Per Second (FPS) based on the interpolation step h 2 = 0.05 s, which is greater than the minimum of 15 FPS for real-time visualization.…”