Nonlinearity in periodic media

The dynamics of the acoustic waves travelling through periodic structures show very special properties, e.g. anisotropic dispersion. In addition, when intense waves are considered, the interaction of nonlinear waves with the material dispersion lead to the emergence of a wide range of intrinsically nonlinear phenomena. I'm working on nonlinear localized waves in different media: supersonic excitations in lattices, solitons and nonlinear waves in layered acoustic media, sonic crystals and macroscopic lattices of oscillators.

Lines:

• Nonlinear waves in phononic crystals
• Nonlinear waves in lattices

Nonlinear waves in phononic crystals

I'm studying nonlinear wave processes in spatially modulated media such as multilayered acoustic media, phononic crystals or sonic crystals. The rich nonlinear dynamics of these system are characterized by its strong dispersion. Here, harmonic generation processes and its relation with their band structure are explored. We found that the nonlinear processes can be enhanced, strongly minimized or simply modified by tuning the material dispersion relation. Thus, the combined action of nonlinearity (harmonic generation) and periodicity (different propagation velocities and attenuation for the different harmonics) results in novel and unexpected phenomena with respect to the linear counterpart, and opens the door to new mechanisms of acoustic wave control and manipulation.

Asymmetric propagation using enhanced self-demodulation in a chirped phononic crystal
A. Cebrecos, N. Jiménez, V. Romero-García, R. Picó, V. Sánchez-Morcillo, L. García-Raffi,
AIP Advances, 6, pp 121601, (2016)

Nonlinear propagation and control of acoustic waves in phononic superlattices
N. Jiménez, A. Mehrem, R. Picó, L. M. García-Raffi, V. Sánchez-Morcillo,
Comptes Rendus Physique, 17 (5), pp 543 - 554, (2016)

Nonlinear self-collimated sound beams in sonic crystals
E. M. Hamham, N. Jiménez, R. Picó, V. Sánchez-Morcillo, L. G. Raffi, K. Staliunas,
Phys. Rev. B, 92, pp 054302, (2015)

Nonlinear waves in lattices

I'm also exploring intense nonlinear waves in lattices of coupled oscillators. An example are strain waves in a chain of cations coupled by realistic interatomic potentials. In this case, the nonlinear ionic interactions and lattice dispersion lead to the formation of supersonic kinks. These intrinsically-nonlinear localized dislocations travel long distances without changing its properties and can explain the formation of dark traces found in muscovite-mica crystals.

Ultradiscrete kinks with supersonic speed in a layered crystal with realistic potentials
J. F. Archilla, Y. A. Kosevich, N. Jiménez, V. Sánchez-Morcillo, L. M. García-Raffi,
Phys. Rev. E, 91 (2), pp 022912, (2015)

Nonlinear dispersive waves in repulsive lattices
A Meherem, N Jiménez, LJ Salmerón-Contreras, X García-Andres, LM Raffi, R Picó, VJ Sánchez-Morcillo,
Physical Review E, 91 (1), pp 002200, (2017)

Macroscopic acousto-mechanical analogy of a microbubble
J. Chaline, N. Jiménez, A. Mehrem, A. Bouakaz, S. D. Santos, V. Sánchez-Morcillo,
The Journal of the Acoustical Society of America, 138 (6), pp 3600-3606, (2015)