Nonlinear square patterns in Rayleigh-Bénard convection
Institut für Physik, Universität Potsdam -
Postfach 60 15 53, 14415 Potsdam, Germany
Accepted: 8 November 2000
We numerically investigate nonlinear asymmetric square patterns in a horizontal convection layer with up-down reflection symmetry. As a novel feature we find the patterns to appear via the skewed varicose instability of rolls. The time-independent nonlinear state is generated by two unstable checkerboard (symmetric square) patterns and their nonlinear interaction. As the bouyancy forces increase, the interacting modes give rise to bifurcations leading to a periodic alternation between a nonequilateral hexagonal pattern and the square pattern or to different kinds of standing oscillations.
PACS: 47.20.Ky – Nonlinearity (including bifurcation theory) / 47.20.Bp – Buoyancy-driven instability / 47.54.+r – Pattern selection; pattern formation
© EDP Sciences, 2001