MARIN presentation on the TopTier project’s results during the CCC (10) plenary meeting.

The IMO Sub-Committee on the Carriage of Cargoes and Containers (CCC) met in London in September. MARIN was invited by the Dutch delegation to assist in drafting the Terms of Reference (TOR) for a Correspondence Group on Prevention of Loss of Containers at Sea.

The Correspondence Group was set up following several submissions to the IMO on the subject, including one based on the results of the TopTier project, which suggested there was room for improvement in multiple areas.

The Terms of Reference aims to establish the accepted use of Lashing Software as a supplement to the Cargo Securing Manual. This will formalise the voyage specific risk assessments that have become common practice over the past decades. In the wake of this step however, the TOR will also address operational guidance for container vessels to ensure that the vessels can indeed be operated within “in design” conditions as considered in the stowage planning. This avoids situations in adverse transits where lashing limits are exceeded under “off design” conditions such as excessive (parametric) roll or waves beyond expectations.

Last but not least, the reliability of container weights, container stowage positions, the condition and strength of containers and lashing gear will also be addressed in the agreed TOR to reduce chances of container loss due to improper stowage or securing.

PIV and CFD results comparison for the same measurement conditions. The PIV measurement area is outlined in black in the CFD figure.

Left: 3D model of the FlowPike fixed to the vessel used in the trial.
Right: View from the aft, showing the measurement area of the FlowPike.

MARIN performed full-scale PIV measurements aboard a 50k DWT tanker using our unique FlowPike PIV device in 2022. The measurements were executed within the JoRes JIP, with the aim of generating a high-quality wake-field dataset to be used for comparison with CFD.

In July 2024, the first PIV-CFD comparison using this dataset was presented at the 21^stInternational Symposium on Application of Laser and Imaging techniques to Fluid Mechanics. Here, we quantified the error of the full-scale PIV measurements and made a comparison between the PIV results with the results of a CFD calculation performed using our in-house RANS code ReFresco.

Overall, the comparison is very favourable; the CFD underpredicted the total power required for propulsion by 3.6%. The velocity fields also compared well, with a small difference observed in the axial velocity on the port side of the vessel, which is thought to originate from an insufficiently accurate roughness model.

Interested? Read the paper ‘Comparison of full-scale PIV measurements with CFD simulations of a ship propeller inflow’.