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

July 24, 2024 at 2:41 pm
Shuangxing Du
Ansys Employee

Hydrodynamic DIffraction analysis does not directly include the mooring line effects.  As there is no any hydrostatic stiffness for surge/sway and yaw motions, large differences of surge at low frequency may occur.  Please check

(1)  If the mooring line effects were included in the RAO calculation in the reference paper.

(2) If yes, please check the mooring configuration in the reference paper. If the pretension is 223.7.4 kN, and the initial attachment position distance is 161m, the unstretched length of the linear cable should be (distance - pretension/stiffness) = 161 - 2337.4/64.19=124.6m.

(3) If the mooring line effects were included in RAO calulcation in the reference paper, please set the unstretched length of the cable to be 124.6m and run Hydrodynamic Response - Stability Analysis with a very small irregular wave significant wave height. The 6x6 mooring stiffness matrix can be output. Then please use this matrix in the Hydrodynamic Diffraction by importing/defining this matrix through Connection - Insert Connection - Connection Stiffness.