Ansys Learning Forum Forums Discuss Simulation Fluids Single floating structure Ansys AQWA Reply To: Single floating structure Ansys AQWA

S.S.S.ShankaVasuki
Subscriber

Hi,

I changed the units of the rotational motions to [radians] as shown in the figure below and these are the new updated the plots I get ( I have ensured the units are correct for the rotational motion in the plots):

What I now observed is that the trend of the variation is better but the values are still not correct. The pitch RAO near the natural frequency is too high and I am not sure what is happening with the surge RAO. I belive that AQWA does not take into account the effect of viscous damping and this might be the reason for this discrepancy? and it needs to be given as an input as additional damping. Maybe I should do that?

Hence, I have some similar questions as my last thread,

  1. Is the specification of the irregular wave correct? (if not could you suggest some values that I can use?)
  2. Do I need to include additional damping and additional added mass matrix in the simulation? As of now there are no additional mass/damping matrices defined. 
  3. Because in the Analysis.LIS file from the results of hydrodynamic diffraction, I get added mass and damping matrix at different frequencies. Do I have to enter them as additional damping matrix in part -> insert -> additional damping?

Please let me know where I am going wrong. 

Thanks!