arXiv subjects

W. Pesch

Publications and source records attributed to W. Pesch.

3 recordsLinked to original sources

arXiv2006

Hexaroll chaos in inclined layer convection

We report experimental observations of hexaroll chaos in inclined layer convection. Two separate populations of defect complexes characterize the defect turbulent state, one the classical penta-hepta defect of hexagonal planform patterns, and the other a short-lived complex capable of self-annihilation. By measuring the defect statistics we show that short-lived defect complexes give rise to linear defect destruction rates. This observation explains previous results in other defect-turbulent pattern forming systems.

nlin.PS↗

arXiv2002

Dislocation Dynamics in Rayleigh-Bénard Convection

Theoretical results on the dynamics of dislocations in Rayleigh-Bénard convection are reported both for Swift-Hohenberg models and the Boussinesq equations. For intermediate Prandtl numbers the motion of dislocations is found to be driven by the superposition of two independent contributions: (i) the Peach-Koehler force derived from the change of a Lyapunov potential with pattern wave number; (ii) a non-potential advection force on the dislocation core by its self-generated mean flow. Their competition allows for the first time to understand the experimentally observed bound dislocation pairs.

cond-mat.soft↗

arXiv1996

Weakly Nonlinear Theory of Pattern-Forming Systems with Spontaneously Broken Isotropy

Quasi two-dimensional pattern forming systems with spontaneously broken isotropy represent a novel symmetry class, that is experimentally accessible in electroconvection of homeotropically aligned liquid crystals. We present a weakly nonlinear analysis leading to amplitude equations which couple the short-wavelength patterning mode with the Goldstone mode resulting from the broken isotropy. The new coefficients in these equations are calculated from the hydrodynamics. Simulations exhibit a new type of spatio-temporal chaos at onset. The results are compared with experiments.

patt-sol↗