Scale effects on the resistance and propulsion characteristics of the Japan Bulk Carrier

The scale effects on the propulsion characteristics of the Japan Bulk Carrier were investigated using numerical simulations of resistance and self-propulsion tests. The mathematical model was based on Reynolds-averaged Navier Stokes equations and for the closure of the governing equations, the SST $k-\omega$ turbulence model was used. The effects of the rotating propeller were modelled using the body force propeller method. Numerical simulations were systematically conducted across four scales ranging from model to full scale and for a wide range of speeds. Additional numerical simulations were performed at model scale with virtual fluid to satisfy both Froude and Reynolds similarity. A verification study was performed to assess numerical uncertainties, while a validation study was conducted using available experimental data. The obtained numerical results enable a detailed investigation of scale effects on ship resistance and propulsion characteristics. Significant scale effects were observed on the integral value of the nominal wake and the radial distribution of the non-dimensional axial velocity. Additionally, scale effects were shown on the wake fraction and hull efficiency, whereas the scale effects on the thrust deduction fraction and the quasi-propulsive efficiency were minimal. The differences between the numerical results obtained using the virtual fluid method and those at full scale with real fluid fall within the bounds of numerical uncertainty.