Maneuverability is crucial for ship operators to understand the performance of escort tugs and improve seamanship. In this work, an escort tug model is taken as the studied ship. Oblique towing tests (OTT) are numerically simulated via the Reynolds-averaged Navier-Stokes (RANS) method. In addition, the details of the flow field under different working conditions are analyzed. The numerical simulation results of the tug provide a basis for obtaining the hydrodynamic derivatives of the bare hull, which is the basis for the subsequent establishment of the maneuvering motion model.
As significant vessels for harbor operations, tugs have a relatively simple hull form, excellent propulsion performance, and great flexibility. It is commonly employed to assist large ships with berthing, departure, escorting, and emergency rescue. Considering that tugs have high requirements for maneuverability, it is necessary to investigate the hydrodynamic performance related to the maneuverability of tugs. Also, understanding the flow around the hull in different states of navigation is important for many designs and operational aspects.
Combining mathematical models and computer simulations to simulate ship motion is an effective way to study ship maneuverability. The hydrodynamic coefficient is one of the essential model parameters in the ship maneuvering motion model. The computational fluid dynamics (CFD) method produces more accurate hydrodynamic coefficients at a cheaper cost. This method has steadily evolved into one of the most widely used ways for calculating hydrodynamic coefficients. Taking the KVLCC2 model as the research object, Feng (Feng, Zou et al. 2015), Liu (Liu 2019) carried out numerical simulation and verification of the oblique towing tests. Zhang (Zhang, Wu et al. 2022) investigated the resistance and moments by carrying out OTT and circular motion tests (CMT). Piaggio (Piaggio, Viviani et al. 2018, Piaggio, Villa et al. 2020, Piaggio, Villa et al. 2020) studied the hydrodynamic force and moment of the escort tug using virtual static and dynamic constraint model tests.