Damping of Surface Waves by Floating Particles

B.R. Sutherland and N.J. Balmforth

Laboratory experiments are performed examining the enhanced damping of surface waves by floating spherical particles. Without particles, wave amplitudes decay exponentially in time; with the particles, the dissipation is enhanced such that waves are arrested in finite time. Initially the decay is exponential with an e-folding time that is inversely proportional to the depth of the particle layer, but independent of particle size. At later times and lower amplitudes, the decay turns into a power law (t_s-t)^q, with exponent lying between q~= 2 and 3. The stopping time, t_s, also decreases with increasing particle layer depth.