The scale effect on wave loads for perforated breakwaters is not a niche technical footnote, it is a correction we can no longer afford to ignore. Physical models have long been the backbone of coastal structure design, but this study demonstrates that smaller models systematically overestimate shoreward peak forces by as much as 23 percent. For engineers relying on those results to size concrete and steel, that bias does not mean a safer structure; it means an overbuilt one, with all the cost and carbon implications that follow.
This matters most where the stakes are highest. Perforated semicircular submerged breakwaters are increasingly specified for projects that demand both wave attenuation and water exchange, think living shorelines, marine habitat restoration, and climate-resilient port infrastructure. When model-to-prototype discrepancies are tied directly to changes in wave transmission, reverse flow, and vortical motion, the message is clear: scaling laws derived from smooth, solid structures do not transfer neatly to porous, curved geometries. The research provides a calibrated correction factor, 1.23 at a 35-to-1 scale with 10 percent perforation, that designers can apply directly. That is the kind of measurable, empirical output that turns a laboratory finding into a field-ready tool.
What is especially valuable here is the methodology itself. By validating a numerical wave flume against both physical model experiments and field pressures at prototype scale, the team closed a loop that too often remains open. Many coastal engineering studies stop at the flume. This one went to the ocean and checked the numbers. That approach, integrated, peer-reviewed, and grounded in real-time validation, is exactly the standard we need more of. It moves the conversation from "this is how we have always done it" to "this is how we know it works."
One specific detail to watch: the perforation rate of 10 percent was the pivot point. Below that, scale effects were less pronounced. Above it, the flow regime changed, and so did the force overestimation. That suggests there may be a design sweet spot where perforation balances hydraulic performance with structural economy. The next logical step is to test whether that threshold holds across different wave climates and seabed conditions. Until then, the takeaway is direct: if you are designing a perforated breakwater from a 1:35 scale model, reduce your peak force coefficient by roughly 20 percent unless you want to bury extra mass on the seabed.