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 comparabl e with boundary-layer damping for surface waves in small cylinders and that its incorporation yields predictions in agreement with the exper imental results of Henderson & Miles (1994) for non-axisymmetric waves on a clean surface with a fixed contact line. In the present note, He nderson & Miles's boundary-layer calculation is supplemented by a calc ulation of interior damping based on Lamb's dissipation integral for a n irrotational flow. The analysis, which omits second-order boundary-l ayer effects, is simpler than that of Martel et al. (which includes th ese effects and is based on an expansion in an inverse Reynolds number ), but yields results of comparable accuracy within the parametric dom ain of the experiments. The corresponding calculations for a fully con taminated (inextensible) surface reduce the discrepancy between calcul ation and experiment but, in contrast to the results for a clean surfa ce, leave a significant residual discrepancy. An unexplained discrepan cy also remains for axisymmetric waves on either a clean or a contamin ated surface.