Abstract
We examine the response of a quasi-two-dimensional colloidal suspension to a localized circular driving induced by optical tweezers. This approach allows us to resolve over 3 orders of magnitude in the Péclet number (Pe) and provide a direct observation of a sharp spatial crossover from far- to near-thermal-equilibrium regions of the suspension. In particular, particles migrate from high to low Pe regions and form strongly inhomogeneous steady-state density profiles with an emerging length scale that does not depend on the particle density and is set by . We show that the phenomenological two phase fluid constitutive model is in line with our results.
- Received 1 November 2020
- Revised 24 May 2021
- Accepted 9 June 2021
DOI:https://doi.org/10.1103/PhysRevLett.127.038003
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