Learning Forum

[Greg Ioannou]

Hello,i have  a floating platform(cylindrical) and when i change the weight of the non diffracted part(not the dimensions) it says:

Does that influence a lot the precision of my results?When im trying to improve the mesh,it appears the below errors:

What should be the optimum mesh for having actual displacement equal to equivalent displacement and not having the above errors????When we increase the element size,must we also change the connection tolerance ?pff

Thank you!

[Mike Pettit]

Hi Greg,

The first info message indicates that your structure is not quite in hydrostatic equilibrium, and this may affect the results slightly. You could consider moving the structure in SpaceClaim so that the mass of displaced water is equal to the structural mass.

The error messages are related to the mesh quality checks that the Aqwa solver applies. In the Hydrodynamic Diffraction Analysis Settings, there is an option to 'Ignore Modelling Rules Violations' - you can use this to change the errors to warnings. However, you should only use this option when there is a small proportion of diffracting elements failing the checks.

The Connection Tolerance in the Mesh settings should not need to be changed from the default value. This is only useful where you have surfaces very close together, or close to the water surface, and you do not want the mesh engine to connect them automatically.

Cheers, Mike

[Greg Ioannou]

Thank you a lot Mike!!Your answers help a lot!May i also ask how to move the structure at spaceclaim for having the e1uilibrium we want?Is the answer here :https://forum.ansys.com/forums/topic/hydrostatic-displacement-properties/ or do i have to do sth different?

Thank you again!!

[Greg Ioannou]

 

 

I have checked it if the answer is in the above thread.

[Mike Pettit]

Hi Greg,

Please use the approach described in the thread you have linked to find the equilibrium position using Aqwa. In SpaceClaim you should use the Design > Move tool to move the structure by the required amounts (i.e. the position offsets calculated in the stability analysis).

Cheers, Mike

[Greg Ioannou]

Thanks for your every answer Mike!