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cybergalactic / MSS

The Marine Systems Simulator (MSS) is software that supplements the textbook "Handbook of Marine Craft Hydrodynamics and Motion Control," 2nd Edition, by T. I. Fossen, published in 2021 by John Wiley & Sons Ltd.

Home Page:https://mss.fossen.biz

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Question about the difference between zero-frequency and infinite-frequency added mass matrix

wtllll opened this issue · comments

commented

Hi @cybergalactic,
I'm really confused about the physics meaning of the zero-frequency added mass matrix $A(0)$ and infinite-frequency added mass matrix$A(\infty)$ . Also, the physics meaning of the zero-frequency potential damping $B(0)$ and infinite-frequency potential damping $B(\infty))$.

In my imagination, the zero-frequency added mass matrix $A(0)$ and the zero-frequency potential damping $B(0)$ are the added mass matrix and potential damping when the vehicle in calm water, right? Then, what's the physics meaning of the infinite-frequency?

Best regards

commented

It might help to think about this by considering a regular wave, z = A * sin(omega * t), exciting your vessel. When you do a physical experiment, generating a wave with infinite frequency is impossible. In practice, the waves will have a positive nonzero frequency omega. The zero frequency gives z = 0, and there are no incoming waves. The infinity frequency is a non-physical value. It is the asymptotic value and the waves can never reach the infinity frequency. However, they can have a very high frequency close to the infinity value.

commented
commented

Got it! Thanks for your explanations!