Putting scale in perspective: CFD for design exploration in the marine industry looks into the differences in CFD simulation at model and full scale and the assumptions involved.

The American Bureau of Shipping (ABS) is the latest company to share results of some tests they ran to help answer this model scale vs full-scale debate. They used STAR-CCM+ to run simulations on multiple hull variants, based on the KCS 3600 TEU container vessel geometry. ABS ran the same cases at both model scale and full scale, then compared the results, along with extrapolated model scale to full-scale results (using ITTC 1978). The results (shown below) gave two conclusions. For situations where viscosity is not dominant, such as bulbous bow investigations, all three methods ranked the different hull variants in the same order of efficiency (figure 1). In cases where hull changes mostly affect the viscous part of the overall resistance, such as aftbody optimization, each of the three methods gave different results: as figure 2 shows, the ranking was completely different for each method (though the relative differences were small in most cases).

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