On the accuracy of the numerical prediction of scale effects on ship viscous resistance

This paper presents a numerical study on the prediction of scale effects on ship resistance, including uncertainty analysis. Grid refinement studies at five different Reynolds numbers have been performed for the calculation of the flow along a flat plate with the Menter and Spalart & Allmars one-equation eddy-viscosity turbulence models; and around three highblock ships (two tankers and a bulkcarrier) with Menter’s model. The numerical uncertainty of the friction resistance coefficient is estimated and the predictions are compared with friction lines available in the literature. The results show that for the level of grid refinement adopted, the numerical uncertainty is negligible and smaller than the differences between the predictions of the two turbulence models. However, these differences are smaller than those between various friction lines. The results of this paper give strong indications that extrapolation of model test results for high-block ships might benefit from including a Rn-independent component in the viscous resistance.