A CFD-Based Surrogate for Duct-Jet AUV Maneuvering

A maneuver model for a duct-jet propelled autonomous underwater vehicle is developed based on unsteady Reynolds averaged Navier–Stokes solutions. The target meter-class vehicle is cylindrical equipped with four cross-type rudders and a ducted propeller operating at a Froude number of 0.39. A conventional propulsion modelling approach based on propeller open water characteristics is employed to embed the duct-jet propulsive model, while axial flow speeds near the duct inlet are additionally extracted from both propeller open-water and static-drift tests. For practical implementation, the number of captive simulations required to extract maneuvering coefficients is reduced, with the kinematic model compensating for the limited dataset. Validation against the high-fidelity simulation indicates that the surrogate model effectively reproduces free-running results for kinematic variables, forces and moment by manifesting dominant features. For the evaluation of solution sensitivity due to spatial discretization, verification studies employing a grid triplet are focused on hull body resistance and propulsion characteristics.