Reply To: AQWA: Hydrodynamic response error

[S.S.S.ShankaVasuki]

 

Ah, thank you for these replies. They are very helpful!!

Also, can I rely on the results of the frequency statistical analysis as it is giving me the best match with the reference article compared to diffraction and response analysis. So my question is – can I directly rely on the results from the frequency statistical analysis? Also, does the nonlinearity influence the RAO largely? 

Another observation:

 

1. My simulation results match well with the reference article for – Surge, Heave and pitch RAOs. But they are extremly low for Sway, Roll and Yaw RAOs compared to the reference (almost by a factor of 10). So I am wondering if my simulation is correct as the dynamics seems not match with the reference. As you mentioned, when wave direction is 180 deg, these RAO will almost be zero (which is what I get in my simulation). But how does the reference article get a higher RAO in sway, roll and yaw for the same set of conditions? Also, the reference article is an experimental study.
2. The reference article mentions that additional damping has to be provided in the surge direction (x) which is approximately 11% of critical damping as shown in the figure, but when I add additional damping to each body with a very high number for x-x element in the matrix and when I check .LIS file, the percentage of critical damping remains 0. So, why is it that is not increasing irrespective of my giving a very high number?