Outboard engine emissions : modelling and simulation of underwater propeller velocity profile using the CFD code FLUENT

The mixing and dispersion created downstream of the marine propeller is critical to the spread and impact of pollutants introduced into the water from outboard motors. Such propulsion systems vent exhaust gases under water where a complex mass transfer of missions occurs to water. This paper presents the modelling and simulation of the propeller velocity profiles and initial plume spread created by marine propellers using the computational fluid dynamics (CFD) software code FLUENT. The model is verified with experimental data measured using a Laser Doppler Anemometer (LDA) in the controlled environment of a laboratory flume channel. A working solution has been developed by employing the sliding mesh method and inducing a rotating flow field. The model has fair agreement with experimental results however the study has exhibited potential for model refinement and improvement. Considerably more work is needed to obtain an overall understanding of the flow field and gain an accurate description of the velocity profile downstream from the propeller.