Reynolds Number Dependence of the Form Factor in Low L/B Fishing Vessels

Abstract

Traditional resistance extrapolation methods, such as the Prohaska approach, assume that the form factor (k) stabilizes as the Reynolds number (Rn) increases, a behavior typically observed in conventional ships with high length-to-beam (L/B) ratios, as shown in Korkmaz et al. (2021) and Terziev et al. (2021). However, our recent combined EFD-CFD study on a fishing vessel with L/B < 4revealed a strong Rn-dependence of the form factor, with discrepancies in 1 + k of up to 40 % between model and full-scale conditions. This behavior, primarily attributed to significant viscous losses in the stern region, contrasts sharply with benchmark hulls such as the KCS. The present work extends this analysis to three fishing vessels with low L/B ratios using double-body (DB) CFDsimulations at multiple scales. The objective is to identify consistent trends in form factor behavior for geometries that remain underrepresented in the literature and to assess the implications for full-scale effective power prediction.