A comprehensive comparison of computational methods on propeller modelling of an AUV

The propeller of a self-propelled marine vehicle is the key to understanding the hull-propeller interactions. The presence of a propeller not only provides the necessary propulsion force, but also significantly modifies the flow field around the marine vehicle. This modification made to flow field influences the hydrodynamic loading experienced by the marine vehicle and thus has an impact on its maneuvering characteristics. There are various methods to represent the actions of a propeller for a range of marine applications within CFD. Actuator disc or virtual disc is one of the earliest and most commonly used approach. This approach solves the body force generated as an equally distributed force over a cylindrical disc while ignoring the geometry of the propeller. Another method to evaluate the force of a propeller is direct simulations, which replicate a propeller based on its true geometry within CFD. This method utilizes the overset mesh technology within CFD that enables the propeller to rotate independently with respect to the background mesh. The present paper primarily used commercially available CFD software package, Star-CCM+ to investigate the accuracy and feasibility of representing the propeller of an Explorer Class AUV using the earlier mentioned methods. The solved advance ratio, and forward velocity from the two methods was benchmarked against open-water trial data.