PATTERN-FORMATION NEAR AN OSCILLATORY INSTABILITY FOR SYSTEMS WITHOUTUP-DOWN SYMMETRY

We present the results of our numerical investigations of the order pa rameter equation associated with an oscillatory instability with a sma ll onset frequency of systems lacking ''up-down'' symmetry, Qualitativ ely different patterns arise depending on whether periodic or more rea listic boundary conditions are used. Among the patterns found are blin king hexagons, traveling rectangular patterns, and states that are dis ordered in space and time, which dominate for realistic boundary condi tions, Experimentally accessible systems for which our predictions cou ld be checked might include non-Boussinesq convection in binary fluid mixtures. (C) 1997 Elsevier Science B.V.