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arXiv · 1510.06911

Time reversal sub-wavelength focusing in bubbly media

Maxime Lanoy·Romain Pierrat·Fabrice Lemoult·Mathias Fink·Valentin Leroy·Arnaud Tourin
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Abstract

Thanks to a Multiple Scattering Theory algorithm, we present a way to focus energy at the deep subwavelength scale, from the far-field, inside a cubic disordered bubble cloud by using broadband Time Reversal (TR). We show that the analytical calculation of an effective wavenumber performing the Independant Scattering Approximation (ISA) matches the numerical results for the focal extension. Subwavelength focusings of lambda/100 are reported for simulations with perfect bubbles (no loss). A more realistic case, with viscous and thermal losses, allows us to obtain a $λ/14$ focal spot, with a low volume fraction of scatterers (phi = 0.01). Bubbly materials could open new perspective for acoustic actuation in the microfluidic context.

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Maxime Lanoy, Romain Pierrat, Fabrice Lemoult, Mathias Fink, Valentin Leroy, Arnaud Tourin. 2015-10-23. Time reversal sub-wavelength focusing in bubbly media. https://doi.org/10.1103/physrevb.91.224202

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