Effect of speed, sea state and wave

Courtesy DNVGL

in droplets after an impact event is much quicker and has a close resemblance to the Richtmyer-Meshkov instability process from a shock wave.

The main step in the modelling process is matching the ship motions in waves to a jet generating process. For this, the hydro- dynamic theory of wedge immersion was used. The jet thickness and velocity exceeding the bow height are then computed. Hourly volumes of spray water over the bow can be computed by applying this method to a ship transiting in an irregular sea. There is unfortunately scarce validation material available, although what we have matches satisfactorily. Results were published at the

Arctic Technology Conference in Copenhagen in March, thereby inviting the industry and other interested parties to provide further validation material.

The development of a realistic prediction method for bow spray has shown that the effect of bow shape, speed and wave direction are very strong. Previous models could hardly distinguish between ship size and they used only speed and wind parameters to predict spray formation at the bow. MARIN believes that for this reason it is fair to say that a major step forward has been made in the ability to better predict sea spray induced icing.

Safe Arctic Logistics, Transport & Operations (SALTO) JIP The main objective of the SALTO JIP is to make a PC software tool, ‘SAFE-IceTRANS’ for the design, risk evaluation and logistic planning of transport & offshore operations in areas with Arctic conditions. Risks include iceberg collision and icing accretion, which are both to be developed from a conditional probabilistic model. This simulation method is very suitable as it contains a comprehensive Arctic conditions database provided by DMI.

The JIP will deliver the ‘SAFE-IceTRANS’ package, including the Offshore Operation package.

Participants are MARIN (coordinator), DMI, AKAC Inc, Imares/WUR and Canatec as initi- ating partners, complemented with MatDan, Shell, Ulstein Sea of Solutions, Heerema Marine Contractors, Noble Drilling, ARiS-Ice and ENI.

End of March the participants decided to go ahead with phase 1 of the SALTO JIP. If you are interested, this is the best time to join!

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