A spectral model for blocking of random waves

A spectral model is presented for blocking of long-crested random waves due to nonuniform collinear adverse current in the steady state situation. The spatial evolution of the spectral components in the region far from the blocking points (far field) is modeled with a spectral wave action balance, which is matched with a uniformly-valid solution in the region near the blocking points (near field). Wave-energy dissipation is taken into account both in the far and near fields, particularly dissipation due to wave breaking. Model results are compared with experimental data for the case of partial blocking and of nominally complete blocking. The value of the onset-breaking parameter γ, which is a calibration parameter, that can best reproduce the observations in both cases is γ ≈ 0.55. The fitted model is able to reproduce the observed patterns of the wave-height variation along the flume well and the observed variance spectra fairly well.