WINDLASS JIP delivers better grip on high windage vessels in ports
In October 2022 the WINDLASS JIP concluded on the 3-D wind flow around container vessels and cruise ships in the port environment as well as the modelling and prediction of the extreme wind loads on such ships and the resulting drift angles, required tug power and mooring line loads. The 3-year project resulted in unique data, new insights and a practical laptop tool for use in ports. In total 25 organisations, including national authorities, port authorities, pilots, linesmen, ship yards, engineering contractors and R&D institutes closely co-operated in this project to conduct the ambitious scope of work.
BackgroundThe first focus of WINDLASS was to collect real world data. For this purpose an extensive measurement campaign was executed to capture storms in port, the effects of large buildings, container stacks and cranes as well as the response of large vessels entering the port and moored to the quayside. For this purpose MARIN’s 'Windcube-200' a versatile 3-D scanning lidar with a range of 6 km supplied by project partner Vaisala, was deployed in the Ports of Rotterdam, Amsterdam, Hamburg and Antwerp in close cooperation with the relevant port authorities, terminal operators, pilots and linesmen. These wind measurements with high resolution in space and time, were complimented with the monitoring of moored vessel motions and line loads. In three cases vessels and terminals were instrumented to measure mooring line loads and vessel excursions. In two cases the drift angle of passing vessels in strong cross wind were captured by 3-D video recordings from shore.
Capturing storms and line loads The monitoring campaign l at Maasvlakte Rotterdam comprised a 10,000 TEU container vessel moored at the ECT terminal when the storm Cristoph striked. on January 21, 2021. The vessel was safely moored with a dynamic mooring system provided by partner ShoreTension which also recorded the extreme tensions.
In the following winter the monitoring campaign focussed on the large car carriers moored at AET in the Port of Antwerp. On April 7, 2022, a severe storm passing the region was captured by the Windcube lidar scanner. Prior to the storm the large car carrier moored at the quayside was instrumented with advanced motion sensors and load cells in the relevant mooring lines.
Storms captured in the JIP exhibited severe wind gusts with speeds which were clearly beyond the extreme values that can be expected based on traditional wind spectra used in mooring analysis.
The measured 3-D wind fields were analysed and compared with the results of fine casting for those locations and time. These GRASP large eddy simulation accounting for the global weather and local obstructions were conducted by partner Whiffle using the global weather model as input.
Versatile laptop tool to predict wind loads and effects on vessel The actual wind loads on container vessels, cruise ships and LNG carriers were computed by the REFRESCO CFD package investigating the wind loads distribution over these vessels and at the same time providing a wind coefficient data base for these present day large vessels. Using this data set and the existing WINDOS kernel software, the dedicated WINDLASS software was then developed by MARIN as an operational laptop tool to predict wind loads, drift angles, tug boat power and mooring loads for such vessels, in arbitrary ports and in any wind condition. As WINDOS utilizes a so called ’building block’ approach, not only the vessel geometry can be modelled in a practical and fast fashion but also the neighbouring container cranes, container stacks, vessels and buildings. For 5 basic ship types, use is made of the dedicated wind load coefficients and by scaling of hull size and adding superstructures and e.g. container stacks, a dedicated geometry is readily defined. The port and terminal geometry can be predefined. In this way the tool is capable to include the effects of the specific port environment on the vessel in the wind loads and its response within minutes. The tool was extensively tested and compared with results of CFD, documented. One of tests of the WINDLASS tool was the modelling of the wind and the wind loads in the port of Tenerife including the effects of the mountains and the buildings surrounding the port.
DMA versus measured vessel excursions and mooring line loads Dynamic Mooring Analysis (DMA) with commercially available software packages were conducted by Arcadis and Siport21 for both cases where storm winds, vessel motions and line loads were captured. By using the measured wind as input for the DMA, the computed vessel motions and line loads could be compared with the measured values.
Specialist CFD analysisAdvanced RANS and LES CFD analysis of 3-D wind conditions were conducted over the port of Rotterdam by partner TU-Eindhoven to investigate and model the wind profile and the fetch over port areas. This task contributed to the modelling of the wind in the Windlass Tool and resulted in recommendations for the use of wind velocity profiles in port areas.
To investigate the detailed flow around neighbouring buildings and moored vessel, detailed numerical analysis with both REFRESCO and GRASP CFD packages were conducted for the Rotterdam Cruise terminal “Wilhelminahaven”. This locations exhibits high rise buildings in the vicinity of the moored cruise vessels. A good correlation between the RANS and LES models was found provided that the mesh was sufficiently detailed. The results also demonstrated the large effects of the high rise buildings on the wind loading of the vessel.
Tool user group Reports and results of WINDLASS JIP are confidential for a period of 3 years. The participants have already agreed to present the main conclusions and selected results in technical papers in the near future.
Last September, the final Version 1.1 of the WINDLASS software tool was released to all participating companies. On October 18, the close-out meeting with the tool users was held to demonstrate the software and to present the applications so far. It is MARIN’s intention to support the WINDLASS/ WINDOS software for a dedicated User Group to be formed soon.