# Non linear analysis of ship motions and loads in large amplitude waves

G. Mortola, A. Incecik, O. Turan, S. E. Hirdaris

Research output: Contribution to journalArticle

10 Citations (Scopus)

### Abstract

A non linear time domain formulation for ship motions and wave loads is presented and applied to the S175 containership. The paper describes the mathematical formulations and assumptions, with particular attention to the calculation of the hydrodynamic force in the time domain. In this formulation all the forces involved are non linear and time dependent. Hydrodynamic forces are calculated in the frequency domain and related to the time domain solution for each time step. Restoring and exciting forces are evaluated directly in time domain in a way of the hull wetted surface. The results are compared with linear strip theory and linear three dimensional Green function frequency domain seakeeping methodologies with the intent of validation. The comparison shows a satisfactory agreement in the range of small amplitude motions. A first approach to large amplitude motion analysis displays the importance of incorporating the non linear behaviour of motions and loads in the solution of the seakeeping problem
Language English A81-A87 7 International Journal of Maritime Engineering 153 A2 10.3940/rina.ijme.2011.a2.wf2 Published - Jun 2011

### Fingerprint

Seakeeping
Nonlinear analysis
Ships
Hydrodynamics
Green's function
Motion analysis

### Keywords

• irregular frequencies
• large amplitude waves
• ship motions

### Cite this

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title = "Non linear analysis of ship motions and loads in large amplitude waves",
abstract = "A non linear time domain formulation for ship motions and wave loads is presented and applied to the S175 containership. The paper describes the mathematical formulations and assumptions, with particular attention to the calculation of the hydrodynamic force in the time domain. In this formulation all the forces involved are non linear and time dependent. Hydrodynamic forces are calculated in the frequency domain and related to the time domain solution for each time step. Restoring and exciting forces are evaluated directly in time domain in a way of the hull wetted surface. The results are compared with linear strip theory and linear three dimensional Green function frequency domain seakeeping methodologies with the intent of validation. The comparison shows a satisfactory agreement in the range of small amplitude motions. A first approach to large amplitude motion analysis displays the importance of incorporating the non linear behaviour of motions and loads in the solution of the seakeeping problem",
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Non linear analysis of ship motions and loads in large amplitude waves. / Mortola, G.; Incecik, A.; Turan, O.; Hirdaris, S. E.

In: International Journal of Maritime Engineering, Vol. 153, No. A2, 06.2011, p. A81-A87.

Research output: Contribution to journalArticle

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T1 - Non linear analysis of ship motions and loads in large amplitude waves

AU - Mortola, G.

AU - Incecik, A.

AU - Turan, O.

AU - Hirdaris, S. E.

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AB - A non linear time domain formulation for ship motions and wave loads is presented and applied to the S175 containership. The paper describes the mathematical formulations and assumptions, with particular attention to the calculation of the hydrodynamic force in the time domain. In this formulation all the forces involved are non linear and time dependent. Hydrodynamic forces are calculated in the frequency domain and related to the time domain solution for each time step. Restoring and exciting forces are evaluated directly in time domain in a way of the hull wetted surface. The results are compared with linear strip theory and linear three dimensional Green function frequency domain seakeeping methodologies with the intent of validation. The comparison shows a satisfactory agreement in the range of small amplitude motions. A first approach to large amplitude motion analysis displays the importance of incorporating the non linear behaviour of motions and loads in the solution of the seakeeping problem

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KW - large amplitude waves

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