Reply To: AQWA: Hydrodynamic response error

[Shuangxing Du]

 

Nonlinearity comes from (1) nonlinear wave exciting force, (2) nonlinear hydrostic force, (3) any nonlinear hull drag force if defined, (4) nonlinear mooring force if the nonlinear cable is defined, (5) nonlinear inertia force (13.4. Inertia Forces in Time Domain Analysis) if motions are large.

The numerical model is ideal, for a port-starboard symmetric structure systems in 180 degree wave condition with other current/wind in other direction, the responses for sway/roll/yaw should be very small. But the model test is not ideal, both the model geometry and wave condition cannot be exactly port/starboard symmetric.

Please check if there is any global mooring stiffness in x-direction, which is the only contribution on the stififness in x-direction as there is no hydrostic stiffness for surge-surge. If not, the critical damping percentage in this direction may not be calculated.

If you find the hydrodynamic responses in frequency statistic analysis agree well with the reference article, the results should be considered to be reliable. Congratulations on your hard work and successful outcomes.