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The resistance of a large Pure Car Truck Carrier (PCTC) with a bulbous bow and a transom stern is evaluated in the present paper. Several cases at nine different ship speeds in calm water are simulated and results are compared with the experimental measurements. The maximum relative error is 0.93% at a Froude number (Fr) of 0.209. The total resistance coefficient of the ship in calm water shows a parabolic trend with increasing Fr, and it reaches a minimum value at Fr = 0.1794. Furthermore, the cases of the ship in regular waves with six different wavelengths and three wave heights are simulated. It is observed that the total resistance exhibits a quadratic relationship with the wavelength when the wave height is fixed. The wave-making resistance increases with the increase in wave height at any fixed wavelength, and it reaches a maximum value when the wave-length is 1.2 times the ship length (Lpp). Additionally, we also investigated the resistance in three different sea states at four different speeds. When the significant wave height of irregular waves is the same as regular waves, the wave-making resistance under irregular waves is much smaller than that of the regular waves. All of these results indicate that the bulbous bow and transom stern can reduce the wave-making and residuary resistances, which can provide a useful reference for the subsequent design and manufacturing of related ships. [ABSTRACT FROM AUTHOR]

The subsea tree acts as an important role in underwater production system. During its installation procedure, hydrodynamic loads significantly affect its dynamic performance. Hence, the drag coefficient of the subsea tree is addressed in detail in the paper by experiment and numerical simulation. Numerical simulation was carried out with finite difference method to get the drag force and drag coefficient. A new experimental method was proposed to conduct an array of model experiments for drag coefficient of subsea tree. The numerical results in drag coefficient were slightly different with experimental results, that was to say, the accuracy and reliability of the experimental data were proved. The drag coefficient is 0.432 in x-direction, 0.479 in y-direction and 0.446 in z-direction, which provide the accurate fundamental hydrodynamic data for underwater production system installation. • Hydrodynamic coefficient plays an important role in hydrodynamic and motion response. • Towing test in the tank can obtain the hydrodynamic data of subsea equipment. • Drag force has a gradual rise with the increase of flow velocity. • Drag coefficient is slightly differ with different flow velocity. [ABSTRACT FROM AUTHOR]