  In this work, the influence of the geometry of lightweight perforated
breakwaters on their performance against green water impact loads is
investigated systematically through a series of numerical simulations. For this
purpose, a fully Lagrangian meshfree particle-based method is adopted to model
transient and impulsive hydrodynamic phenomenon with free surface and complex
geometry. The green water flow is represented by a dam-break problem; the
breakwater is modeled as a perforated plate and the protected installation as a
vertical wall. Computed impact force, moment, and impulse on the breakwater and
protected wall show nonlinear effects, and the main geometric parameter is the
open-area ratio. In addition, the increase in the breakwater height is
effective only for low open-area ratios. The influence of the arrangement of
the holes are also investigated. Different flow patterns are obtained for small
and large gaps between the breakwater and the wall. The relation between the
loads on the breakwater and the wall also provides the basis for the optimal
design of the breakwater, considering the tolerant hydrodynamic loads of
protected structures.
