Wave Runup Loading Behind a Semipermeable Obstacle

This paper describes an investigation of the interaction of breaking solitary wave runup with a two-dimensional semipermeable (vegetated) obstacle and the resulting wave loading on a downstream cylinder. The OpenFOAM model, together with an IHFOAM module for mangrove-fluid interaction, are used for 276 numerical experiments, performed for a wide range of damping coefficients. In general, wave heights inside and just downstream of the obstacle were found to increase, compared with the bare earth case, with reflection from and inside the obstacle as the major factor. By contrast, wave loads decreased strongly when sheltered by the obstacle, with increasing damping coefficients leading to lower loads, but with considerable scatter. This paper provides several different methods to estimate wave runup loads behind semipermeable obstacles, with results presented in forms that may prove useful for design.