Numerical Study on Wave-induced Motion of Offshore Structures Using Cartesian-grid based Flow Simulation Method

Title & Authors
Numerical Study on Wave-induced Motion of Offshore Structures Using Cartesian-grid based Flow Simulation Method
Nam, Bo Woo; Kim, Yonghwan; Yang, Kyung Kyu; Hong, Sa Young; Sung, Hong Gun;

Abstract
This paper presents a numerical study of the wave loads acting on offshore structures using a Cartesian-grid-based flow simulation method. Finite volume discretization with a volume-of-fluid (VOF) method is adopted to solve two-phase Navier-Stokes equations. Among the many variations of the VOF method, the CICSAM scheme is applied. The body boundary conditions are satisfied using a porosity function, and wave generation is carried out by using transient (wave or damping) zone approaches. In order to validate the present numerical method, three different basic offshore structures, including a sphere, Pinkster barge, and Wigley model, are numerically investigated. First, diffraction and radiation problems are solved using the present numerical method. The wave exciting and drift forces from the diffraction problems are compared with potential-based solutions. The added mass and wave damping forces from the radiation problems are also compared with the potential results. Next, the wave-induced motion responses of the structures are calculated and compared with the existing experimental data. The comparison results are fairly good, showing the validity of the present numerical method.
Keywords
Offshore Structure;Cartesian-grid;Wave-induced Motion;Flow Simulation Method;Wave excitation force;Added mass;Wave damping;
Language
Korean
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References
1.
Nam, B.W., Hong, S.Y., Kim, Y., 2010. Numerical Simulation of Wave Forces acting on Fixed Offshore Structures Using a Hybrid Scheme. Journal of Ocean Engineering and Technology, 24(6), 1-7.

2.
Ferziger, J.H., Peric, M., 2002. Computational Methods for Fluid Dynamics. Springer-Verlag, Heidelberg.

3.
Journee, J.M.J., 1992. Experiments and Calculations on 4 Wigley Hull Forms in Head Waves. Report0909, Delft University of Technology.

4.
Hu, C., Kashiwagi, M., 2007. Numerical and Experimental Studies on Three-Dimensional Water on Deck with a Modified Wigley Model. Proceedings of 9th International Conference on Numerical Ship Hydrodynamics, Ann Arbor, Michigan.

5.
Kim, J.W., Kyoung, J.H., Ertekin, R.C., Bai, K.J., 2003. Wave Diffraction of Steep Waves by Bottom-mounted Vertical Cylinders. Proceedings of 22th OMAE, Canvun.

6.
Pinkster, J.A., 1976. Low Frequency Second Order Wave Forces on Vessels Moored at Sea. Proc. 11th Symp. Naval Hydrodyn..

7.
Ubbink, O., Issa, R.I., 1999. A Method for Capturing Sharp Fluid Interfaces on Arbitrary Meshes. Journal of Computational Physics, 153, 26-50.