Coupled heave and pitch motions of a high speed boat

  • Last Post 16 May 2019
Jafar posted this 14 May 2019


I'm using Ansys CFX to simulate the motion of a high-speed boat on a sea with head sinusoidal waves. I have an enquiry about how to get the coupled motions of heave and pitch (translational motion in the z-axis and rotational motion about the y-axis) of the centre of gravity of the boat. I have used the Modal analysis platform to get the two motion but separately by using remote displacement function and then fixing the other 5 motions that the boat can do. My aim now is to get the two coupled motions in one simulation. I tried to simulate the coupled motion using Modal analysis but it does not seem to be working.  

Any help would be very much appreciated. 

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SandeepMedikonda posted this 14 May 2019

What is the end goal of your simulation? Are you trying to extract the motion profiles from CFX and use it in Mechanical? If so, which analysis? Static Structural?

P.S: Pictures will help understand the problem better. 

Jafar posted this 16 May 2019

Thank you very much for your reply. My goal is to validate some analytical results I have obtained from nonlinear equations. I'm simulating to get the displacement in the vertical direction (translational displacement aka heave) and the rotational displacement about the transverse axis of the CG (aka pitch). I use the Modal platform to create a mode shape file and then insert it as profile data file in the unsteady CFX simulation. The mode shape file cannot have both motions at the same time but each separately so I have to run the unsteady case twice, once with the pitch motion as mode shape and one with heave motion as mode shape. I'm trying to simulate both motion together (coupled) in one unsteady CFX run. 

What pictures would you like to see? 

Thank you very much again your help is very much appreciated.