Collective waves in dense and confined microfluidic droplet arrays
arXiv:1502.05519 · doi:10.1039/C5SM01116G
Abstract
Excitation mechanisms for collective waves in confined dense one-dimensional microfluidic droplet arrays are investigated by experiments and computer simulations. We demonstrate that distinct modes can be excited by creating specific `defect' patterns in flowing droplet trains. Excited longitudinal modes exhibit a short-lived cascade of pairs of laterally displacing droplets. Transversely excited modes obey the dispersion relation of microfluidic phonons and induce a coupling between longitudinal and transverse modes, whose origin is the hydrodynamic interaction of the droplets with the confining walls. Moreover, we investigate the long-time behaviour of the oscillations and discuss possible mechanisms for the onset of instabilities. Our findings demonstrate that the collective dynamics of microfluidic droplet ensembles can be studied particularly well in dense and confined systems. Experimentally, the ability to control microfluidic droplets may allow to modulate the refractive index of optofluidic crystals which is a promising approach for the production of dynamically programmable metamaterials.
13 pages, 17 figures
References in corpus (10)
- Statistical mechanics and dynamics of solvable models with long-range interactions
- Phonons in a one-dimensional microfluidic crystal
- Transport coefficients of off-lattice mesoscale-hydrodynamics simulation techniques
- Relevance of angular momentum conservation in mesoscale hydrodynamics simulations
- Hydrodynamic interaction in confined geometries
- Anomalous Microfluidic Phonons Induced by the Interplay of Hydrodynamic Screening and Incompressibility
- Hydrodynamic crystals: collective dynamics of regular arrays of spherical particles in a parallel-wall channel
- Screening by symmetry of long-range hydrodynamic interactions of polymers confined in sheets
- Active and driven hydrodynamic crystals
- Mode Coupling of Phonons in a Dense One-Dimensional Microfluidic Crystal