Stability of Three-Dimensional Interfacial Waves Under Subharmonic Disturbances

This study examines the stability regimes of three-dimensional interfacial gravity waves. The numerical results of the linear stability analysis extend the three-dimensional surface waves results of Ioualalen and Kharif (1994) to three-dimensional interfacial waves. An approach of the collocation type has been developed for this purpose. The equations of motion are reduced to an eigenvalue problem where the perturbations are spectrally decomposed into normal modes. The results obtained showed that the density ratio plays a stabilizing factor. In addition, the dominant instability is of three-dimensional structure, and it belongs to class I for all values of density ratio.