Learning Forum

[r.abbasi]

Hi, I would appreciate an answer to this question. I have solved the RAO in a JONSWAP spectrum for different floats in the frequency domain, but there are significant discrepancies with my experiments, especially for one of the floats (blue line) which has a slope on its body, also after resonance frequency for the orange one. How can I improve the accuracy?

How can I increase the frequency resolution for the numerical RAOs, especially around resonance? I set the total number of frequencies to 100, but I don't see any changes

RAO in experiments is done with displacement of the float relative to wave amplitude, with consistent wave heights maintained throughout all experiments, and wave height was equal to significant wave height in numerical analysis in irregular waves.

[Shuangxing Du]

What are the ratios of the wave amplitudes and the model sizes in the model tests?  In the blue-line and orange-line floats, some or all the hull surfces near mean water level are not in vetical, the non-linear effects will be involved in the model tests if the wave amplitudes are relatively high. The incident wave may also not be the Airy wave (linear wave) at higher wave frequencies.  If it is the case, please try to run the time domain hydrodynamic response in the regular wave, the response amplitude divided by the incident wave amplitude could be more comparable to the model test data, as this time domain response data contains the nonlinear hydrodynamic and hydrostatic effects.  The frequencies in the RAO output in the frequency domain statistic analyis are determined by the program, among which the refined frequency points are given at (1) peak frequency of the wave spectrum, (2) response natural frequencies.