A Comprehensive Study on the Influence of Scale and Draft Variations on Form Factor Using a Combined EFD/CFD Approach

Paper in proceeding, 2025

In recent years, extensive research has been conducted on predicting a ship’s form factor and the associated scale effects, as the accuracy of these estimates has been questioned. This study examines the differences between model and full-scale CFD-based form factor calculations using a newly developed approach known as the 2-k method. This method enhances the precision of form factor estimation by applying full-scale computations, particularly in scenarios involving stern flow separation. The study evaluates three benchmark hulls and two bulk carriers, revealing a strong dependence of the form factor on grid resolution due to variations in scale factors. The results align well with findings from existing literature. Additionally, a systematic variation of transom submergence demonstrates consistency in form factor predictions at both model and full scale. Through a comprehensive analysis of scale and draft variations, the study confirms that the 2-k method is a robust and reliable approach, capable of accurately predicting the form factor even in the presence of recirculating flow behind a submerged transom.