CFD-based stepwise integration and analysis of hull appendages on the resistance performance of a displacement vessel

This study presents a comprehensive numerical investigation into the hydrodynamic effects of commonly adopted hull appendages, which are the bulbous bow, skeg, and sonar dome, on a displacement ship operating across a wide Froude number range (Fr = 0.16 to 0.41). Simulations were conducted using Reynolds-Averaged Navier–Stokes (RANS) equations in combination with the Volume of Fluid (VOF) method to capture free-surface effects. A four-stage stepwise configuration scheme was employed: bare hull, hull with bulbous bow, with bulbous bow and skeg, and finally the fully appended hull including the sonar dome. Results indicate that the bulbous bow contributed the most significant reduction in total resistance, which is up to 8.62% at Fr = 0.26, through wave interference and improved pressure distribution. The skeg aided aft-body flow alignment while the sonar dome showed negligible effect on resistance within typical operating conditions. All appended configurations exhibited increased frictional resistance due to surface area growth, with the full configuration showing an average increase of 6.97%. However, these increases were offset by considerable reductions in pressure resistance, particularly in transitional speeds, with a maximum pressure drag reduction of 29.03% at Fr = 0.24. The novelty of this study lies in its systematic, configuration-based evaluation of multiple appendages under consistent CFD conditions, enabling clear quantification of trade-offs between frictional and pressure resistance. The findings offer practical insights into appendage integration strategies for performance optimization in displacement vessels and guidelines for naval architects in selecting and integrating appendages to optimize resistance characteristics during the early design stages of displacement vessels.