A note on interior vs. boundary-layer damping of surface waves in a circular cylinder

Martel et al. (1998) have shown that interior damping may be comparable with boundary-layer damping for surface waves in small cylinders and that its incorporation yields predictions in agreement with the experimental results of Henderson & Miles (1994) for non-axisymmetric waves on a clean surface with a fixed contact line. In the present note, Henderson & Miles's boundary-layer calculation is supplemented by a calculation of interior damping based on Lamb's dissipation integral for an irrotational flow. The analysis, which omits second-order boundary-layer effects, is simpler than that of Martel et al. (which includes these effects and is based on an expansion in an inverse Reynolds number), but yields results of comparable accuracy within the parametric domain of the experiments. The corresponding calculations for a fully contaminated (inextensible) surface reduce the discrepancy between calculation and experiment but, in contrast to the results for a clean surface, leave a significant residual discrepancy. An unexplained discrepancy also remains for axisymmetric waves on either a clean or a contaminated surface.