## Fluids

#### riding water buoy simulation in ansys aqua/ workspace

• Krisztián Mihályi
Subscriber

Hi, I'm student, and new in simulation and now I'm stucked. Water-buoy hydrodinamic diffraction is counted, Hydrodynamic response is ready,. BUT for real animation these need to be put together somehow and I didn't find any tutorial how to do. See pictures what I have.  I  didn't find simulation what is showing reality on Youtube.

What is the right software for it, or what is the next step in the workbench for real visualisation ? (water and buoy movement together) Can somebody help?

Thanks

• Mike Pettit
Ansys Employee

Hello,

Time domain incident wave surface animation will be included in Release 2023 R1, which should be available soon. This will allow you to display the long- or short-crested wave motions at the same time as the buoy movement in an Animation result.

In the current versions (Release 2022 R2 or older), you would need to use the Aqwa Graphical Supervisor (AqwaGS), which can only display a long-crested wave.

I hope this helps.

Mike

• Krisztián Mihályi
Subscriber

Meanwhile I founded a realistic simulation (made in fluent) where waves and ship interact well. Can I do the simulation based  on this video with some added mechanical computation due to cables to reach the desired result? Than what can be the order of steps?  Can it be works at all?

• Mike Pettit
Ansys Employee

Including the cables would be very complicated to set up, as you would need a two-way coupling between Mechanical (ship + mooring system forces/motions) and Fluent (fluid forces/motions), plus additional modelling for the drag forces on the cables.

What results are you trying to calculate? If you want to check the air gap between the incident wave surface and a point on the buoy, you can do this in the Hydrodynamic Response system by adding a Connection Point to the buoy at the position of interest, and then adding a Structure Motions > Structure Position > Actual Response result with 'Component' set to 'Global Z'; 'Reference Point' set to your Connection Point, and 'Motion Relative To' set to 'Wave Surface'.

Mike

• Krisztián Mihályi
Subscriber

The buoy movement what I calculated is too chaotic, and without see how buoy riding on the waves I have no clue what to modify. So nothing elso to calculate, but result I got need to fine tune.https://files.fm/u/r923vwrjf?ak=7f03d

• Mike Pettit
Ansys Employee

Unfortunately I’m not allowed to download anything from this forum – if you have a customer account, please create a Support Request on the Customer Portal and upload the files there (or contact your account manager/channel partner).

For a small buoy structure I would expect that the Keulegan-Carpenter number is relatively large, i.e. the drag forces are significant compared to the diffraction forces. It sounds like you may need to add some drag modelling to your Aqwa model, which you can do by including Morison Disc elements on each end of the buoy cylinder; and/or by adding Morison Hull Drag/Current Force Coefficients tables, and defining appropriate force coefficients for the structure.

Mike