The objective of this study is to examine the nonlinear fluid characteristics near and inside a moonpool in various sea conditions. We estimate the flow of the free surface in a moonpool taking into account the viscosity effect and the hydrodynamic forces that affects a moonpool and hull through CFD calculations. The comparison of horizontal forces per wave length shows that the hydrodynamic force is greater for the long wave length than short wave length, and the greatest hydrodynamic force acts on the moonpool when the wave length is equal to the ship’s length. The horizontal force decreases as the wave amplitude decreases, and the hydrodynamic force acting on the moonpool in λ=LBP is 10 times that in λ=LBP/3. The free surface demonstrates the piston mode, in which it oscillates up and down while remaining essentially flat, and the rise of the free surface level increases as the wave length increases. We can assume that the hydrodynamic force acting on the moonpool increases owing to the effect of a strong vortex for λ=LBP and owing to the rise of the free surface level for λ=LBP ×2.

1. Introduction
2. Numerical calculation
3. Added resistance in waves
4. Conclusion
References

• Sang-min Lee(Dept. of Marine Science and Production, Kunsan National University)
• Nam-Kyun Im(Division of Marine Transportation System, Mokpo National Maritime University) Corresponding author