Particle image velocimetry and infrared thermography in a levitated droplet with nanosilica suspensions

    Authors

    A. Saha; S. Basu;R. Kumar

    Comments

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    Abbreviated Journal Title

    Exp. Fluids

    Keywords

    ACOUSTIC LEVITATION; EVAPORATION; SYSTEMS; FLOW; Engineering, Mechanical; Mechanics

    Abstract

    Preferential accumulation and agglomeration kinetics of nanoparticles suspended in an acoustically levitated water droplet under radiative heating has been studied. Particle image velocimetry performed to map the internal flow field shows a single cell recirculation with increasing strength for decreasing viscosities. Infrared thermography and high speed imaging show details of the heating process for various concentrations of nanosilica droplets. Initial stage of heating is marked by fast vaporization of liquid and sharp temperature rise. Following this stage, aggregation of nanoparticles is seen resulting in various structure formations. At low concentrations, a bowl structure of the droplet is dominant, maintained at a constant temperature. At high concentrations, viscosity of the solution increases, leading to rotation about the levitator axis due to the dominance of centrifugal motion. Such complex fluid motion inside the droplet due to acoustic streaming eventually results in the formation of a ring structure. This horizontal ring eventually reorients itself due to an imbalance of acoustic forces on the ring, exposing larger area for laser absorption and subsequent sharp temperature rise.

    Journal Title

    Experiments in Fluids

    Volume

    52

    Issue/Number

    3

    Publication Date

    1-1-2012

    Document Type

    Article

    Language

    English

    First Page

    795

    Last Page

    807

    WOS Identifier

    WOS:000300848900020

    ISSN

    0723-4864

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