NONLINEAR COMPETITION BETWEEN SMALL AND LARGE HEXAGONAL PATTERNS

Recent experiments by Kudrolli, Pier, and Gollub [Physica D (to be pub lished)] on surface waves, parametrically excited by two-frequency for cing, show a transition from a small hexagonal standing wave pattern t o a triangular ''superlattice'' pattern. We show that generically the hexagons and the superlattice wave patterns bifurcate simultaneously f rom the flat surface state as the forcing amplitude is increased, and that the experimentally observed transition can be described by consid ering a low-dimensional bifurcation problem. A number of predictions c ome out of this general analysis. [S0031-9007(98)07195-6].