To quantify loading due to breaking waves, model tests are currently the option of choice. However, during such tests it is suspected that scale effects can lead to an overestimation of the prototype loading. To gain more insight in how conservative impact load measurements at model scale are, the BreaKin Joint Industry Project was started. Wave-in-deck model tests were carried out in MARIN’s Depressurised Wave Basin (DWB) at two scales (1:25 and 1:50) in atmospheric and depressurized condition, to quantify scale effects and investigate to which extend entrapped air in the wave and during the impact is of influence. The results of the model tests have shown that:

• The direct impact was the dominant loading process involved in the measured global impact loads for the specific type of tests.
• The shape of the wave just before impact is strongly affected by the ambient pressure (density ratio) and has a large influence on the resulting impact load.
• The negative vertical impact loads appear to be reduced in depressurized condition, and when testing at larger scale (scale 1:25 vs scale 1:50).
• Based on the comparisons between the measured loads at both scales, it appears that the measured loads at scale 1:50 are on the conservative side.
• Air entrapment and building jets on the front of the deck are observed, resulting mainly in variations in local loading.

To further understand the underlying physical processes responsible for the observations made within the BreaKin JIP, CFD simulations are proposed. In CFD, parameters can be systematically varied one-by-one to assess their individual influence, and detailed visualisations can provide in-depth understanding of the flow phenomena. As a starting point, one specific impact test of the BreaKin JIP was recalculated in CFD. A close match with the model tests results was obtained, indicating the potential value of the proposed scope of work (and also helping to quantify the dynamic response in the measurements).