Investigation of Multiply Composite Artificial Bars for Bragg Scattering of Water Waves

Abstract

The Bragg scattering of water waves by multiply composite artificial bars was investigated both theoretically and experimentally. Miles' theory is first employed to derive general formulae to calculate Bragg reflection coefficients for multiply composite artificial bars with different shapes, spacings, bar heights, bar footprint, and the number of bars. The theory provides explicit expressions in estimating Bragg reflections over multiply composite bars in practical engineering applications. The undulating oscillation components expanded with respect to the bottom slope and curvature components in the numerical model can increase the accuracy for the simulation of Bragg scattering. Experiments of Bragg reflection over multiply rectangular artificial bars were also conducted in a wave flume. Analytical solutions are in good agreement with numerical simulations of evolution equation of mild-slope equation (EEMSE) and laboratory experiments. Influence parameters that may lead to the optimal combination of a multiple artificial bar to increase the bandwidth of Bragg resonance were studied.