Nonchaotic Rayleigh-Bénard Convection with Four and Five Incommensurate Frequencies

The onset of time dependence of Rayleigh-B\'enard convection in water is studied in a rectangular container with aspect ratio 9.5\ifmmode\times\else\texttimes\fi{}4.6. Quasiperiodic states are observed exhibiting four and five incommensurate frequencies. All but one of the modes are predominantly localized in different parts of the cell; this localization may explain the coexistence of more than three incommensurate frequencies without chaos.