Abstract
We investigate the acoustic normal modes ("phonons") of a 1D microfluidic droplet crystal at the crossover between 2D flow and confined 1D plug flow. The unusual phonon spectra of the crystal, which arise from long-range hydrodynamic interactions, change anomalously under confinement. The boundaries induce weakening and screening of the interactions, but when approaching the 1D limit we measure a marked increase in the crystal sound velocity, a sign of interaction strengthening. This nonmonotonous behavior of the phonon spectra is explained theoretically by the interplay of screening and plug flow.
Original language | American English |
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Article number | 124502 |
Journal | Physical Review Letters |
Volume | 99 |
Issue number | 12 |
DOIs | |
State | Published - 20 Sep 2007 |
Externally published | Yes |