Related Experiment Video
Updated: Jun 8, 2026

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Front dynamics and pinning-depinning phenomenon in spatially periodic media
F Haudin1, R G Elías, R G Rojas
1INLN, Université de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, 06560 Valbonne, France.
Abstract:
Front propagation in one- and two-dimensional spatially modulated media is studied both experimentally and theoretically. The pinning-depinning phenomenon, long ago predicted by Pomeau [Physica D 23, 3 (1986)], is obtained and verified experimentally in a nematic liquid-crystal cell under various configurations of optical forcing. The front dynamics is characterized with respect to the different forcing parameters and the observations are compared with numerical simulations of a full model for the tilt angle of the liquid crystals under optical feedback. A spatially forced dissipative ϕ4 model is derived near the points of nascent bistability. From this model we derive analytical results that account qualitatively for the observed front dynamics and pinning range. Localized structures of different sizes and shapes are found to exist inside the pinning range and experimentally proved to be stable states of the spatially forced system.
Related Concept Videos
Interference and Diffraction
First Law: Particles in Two-dimensional Equilibrium
Newton's first law tells us about the...
The de Broglie Wavelength
Atomic Nuclei: Nuclear Relaxation Processes
Magnetostatic Boundary Conditions
Magnetic Damping
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
