抄録
Wave generation on the surface of a liquid due to the instability of free-surface shear layer is investigated experimentally and theoretically. A laser beam refraction technique is employed for measurement of periodic two-dimensional waves arising in the jet initial region. It is shown that the linear perturbation equation has temporally-neutral, spatially-unstable solutions for local velocity profiles predicted for an initially-laminar shear layer. The frequency of the most-unstable solution shows fair agreement with the measured dominant frequency of the wave. The linear stability analysis can be simplified drastically by introducing linear or piecewise-linear approximation of the velocity profile. Such simplification does not result in large discrepancy from the detailed-model predictions, or experimental data, except in the initial region of the jet where there is arbitrariness in approximation with simplified velocity profiles.
