CFD is a useful tool for ship designers looking for accurate predictions of the fuel efficiency achieved by a certain combination of hull, propeller and Energy Saving Devices (ESDs). Such predictions are key to meeting ever-increasing demands for reductions in emissions. However, CFD simulations of propeller-hull interaction can be very costly in terms of computational effort due to the need to resolve the unsteady flow around the rotating propeller.
A popular approach to alleviate this cost, that has seen much practical use in industry, is the use of body forces (momentum sources) to represent the rotating propeller. There are many ways to describe the body force distribution in the fluid for a certain propeller and there are many options for what flow solver to use. In a previous meeting of the Society, an open-source framework for easily creating coupled solvers using an arbitrary combination of models was presented.
Here, one of these coupled solvers is used to predict the local flow behind the propeller, as well as integral coefficients indicating performance, of four different vessels: a bulk carrier fitted with an Energy Saving Device, a fast container ship, a tanker and a fully appended twin-screw navy destroyer. All simulations are compared to available experimental data. Conclusions are drawn based on the success of the coupled solver to predict the local flow behind the propeller for each individual hull and how this relates to the vessel type and the local stern geometry.
