Learning Forum

[pohigor]

I modeled a symmetrical ship hull in the xz plane using Aqwa to determine the hydrodynamic coefficients for added mass and potential damping. I imported the geometry into Design Modeler and aligned the xy plane with the waterline, setting the plane's origin at the ship's centerline. I divided the hull geometry into two sections—dry and wet—and successfully created a mirrored mesh, ensuring that the port side mesh was symmetrical to the starboard side. After reimporting the geometry into Aqwa, I added a mass point. As well explained in Faltinsen's book, for the case without forward speed, the relations Aij = Aji and Bij = Bji must be respected. However, in my model, this is not observed for all terms. As examples are the terms A35 and A53:

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Does anyone know why the symmetry of the matrix is ​​not respected?
Thanks in advance.

Wave directions: -180 to 180 / number of directions: 9 
Wave periods: 180s to 2s / number of periods: 21 
Ship length: 55m 
Mesh size: 0.4m

[Shuangxing Du]

Could you please set the unit of degree as [rad] in your Aqwa Workbench project?  A35 and A53 should be very close if the unit of A53 is in [kg.m/rad]. 

[pohigor]

converting to radians the values ​​become close. thanks for your help.