Examinando por Autor "Falcón, Claudio"

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Emergence of spatiotemporal dislocation chains in drifting patterns
(American Institute of Physics, 2014-06-16) Clerc, Marcel G.; Falcón, Claudio; García-Ñustes, Mónica A.; Odent, Vincent; Ortega-Piwonka, Ignacio
One-dimensional patterns subjected to counter-propagative flows or speed jumps exhibit a rich and complex spatiotemporal dynamics, which is characterized by the perpetual emergence of spatiotemporal dislocation chains. Using a universal amplitude equation of drifting patterns, we show that this behavior is a result of a combination of a phase instability and an advection process caused by an inhomogeneous drift force. The emergence of spatiotemporal dislocation chains is verified in numerical simulations on an optical feedback system with a non-uniform intensity pump. Experimentally this phenomenon is also observed in a tilted quasi-one-dimensional fluidized shallow granular bed mechanically driven by a harmonic vertical vibration.
Subharmonic wave transition in a quasi-one-dimensional noisy fluidized shallow granular bed
(American Physical Society, 2010-04-19) Ortega-Piwonka, Ignacio; Clerc, Marcel G.; Falcón, Claudio; Nicolás, Mujica
We present an experimental and theoretical study of the pattern formation process of standing subharmonic waves in a fluidized quasi-one-dimensional shallow granular bed. The fluidization process is driven by means of a time-periodic air flow, analogous to a tapping type of forcing. Measurements of the amplitude of the critical mode close to the transition are in quite good agreement with those inferred from a universal stochastic amplitude equation. This allows us to determine both the bifurcation point of the deterministic system and the corresponding noise intensity. We also show that the probability density distribution is well described by a generalized Rayleigh distribution, which is the stationary solution of the corresponding Fokker-Planck equation of the universal stochastic amplitude equation that describes our system.
Symmetry-induced pinning-depinning transition of a subharmonic wave pattern
(American Physical Society, 2012-03-05) Garay, Jeremías; Ortega-Piwonka, Ignacio; Clerc, Marcel G.; Falcón, Claudio
The stationary to drifting transition of a subharmonic wave pattern is studied in the presence of inhomogeneities and drift forces as the pattern wavelength is comparable with the system size. We consider a pinning-depinning transition of stationary subharmonic waves in a tilted quasi-one-dimensional fluidized shallow granular bed driven by a periodic air flow in a small cell. The transition is mediated by the competition of the inherent periodicity of the subharmonic pattern, the asymmetry of the system, and the finite size of the cell. Measurements of the mean phase velocity of the subharmonic pattern are in good agreement with those inferred from an amplitude equation, which takes into account asymmetry and finite-size effects of the system, emphasizing the main ingredients and mechanism of the transition.