This paper discusses the hydrodynamic characteristics of a catamaran at low speed. In this study, the Delft 372 catamaran model was selected as the target hull to analyze the hydrodynamic characteristics by using the RANS (Reynold-Averaged Navier-Stokes) numerical method. First, the turbulence study and mesh independent study were conducted to select the appropriate method for numerical calculation. The numerical method for the CFD (Computational Fluid Dynamic) calculation was verified by comparing the hydrodynamic force with that obtained experimentally at high speed condition and it rendered a good agreement. Second, the virtual captive model test for a catamaran at low speed was conducted using the verified method. The drift test with drift angle 0-180 degrees was performed and the resulting hydrodynamic forces were compared with the trends of other ship types. Also, the pure rotating test and yaw rotating test proposed by Takashina, (1986) were conducted. The Fourier coefficients obtained from the measured hydrodynamic force were compared with those of other ship types. Conversely, pure sway test and pure yaw test also were simulated to obtain added mass coefficients. By analyzing these results, the hydrodynamic coefficients of the catamaran at low speed were estimated. Finally, the maneuvering simulation in low speed conditions was performed by using the estimated hydrodynamic coefficients.

Abstract
1. Introduction
2. Theory Background
    2.1 Coordinate system
    2.2 Governing equation
    2.3 Dimensionless quantity
    2.4 CFD-Based modeling
    2.5 Captive model test
3. Results
    3.1 Case study
    3.2 CFD verification
    3.3 Results of virtual captive model test
4. Conclusion
References

• Thi Loan Mai(Graduate Sschool of Changwon National University)
• Tien Thua Nguyen(Graduate Sschool of Changwon National University)
• Myungjun Jeon(Graduate Sschool of Changwon National University)
• Hyeon Kyu Yoon(Changwon National University) Corresponding author