Confined water effects on the viscous flow around a tanker with propeller and rudder

Artikel i vetenskaplig tidskrift, 2013

A ship travelling in canals or narrow channels may encounter hydrodynamic forces and moments caused by a nearby side bank. Since most canals are shallow the effect of the bottom can also be considerable. Knowledge of these effects is crucial for safe navigation. The present paper introduces a study in the framework of a project applying Computational Fluid Dynamics (CFD) in the prediction of confined water effects. Using a steady state Reynolds Averaged Navier-Stokes solver, this study investigates the shallow-water and bank effects on a tanker moving straight ahead at low speed in a canal characterized by surface piercing banks. The tanker is fitted with a rudder and a propeller at a zero propeller rate and at self-propulsion. In the systematic computations, a series of cases are considered with varying water depth and ship-to-bank distance, as well as different canal configurations. In the computations, the double model approximation is adopted to simulate the flat free surface. The non-rotating propeller is treated as an appendage composed of shaft and blades, while the operating propeller is approximated by body forces, simulated by a lifting line potential flow model. Validation of forces and moments against experimental data has been performed in previous studies. The emphasis of the present paper is placed on the effects on the flow field and the physical explanation of these effects. © 2013 - IOS Press and the authors. All rights reserved.