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.
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References
Abe Y, Yamamoto Y, Hyuga D, Aoki K, Fujiwara A (2007) Interfacial stability and internal flow of a levitated droplet. Microgravity Sci Technol 19:33–34
Basu S, Cetegen BM (2008) Modeling of thermophysical processes in liquid ceramic precursor droplets heated by monochromatic irradiation. J Heat Transf 130:071501.1–071501.8
Brandt EH (2001) Acoustic physics suspended by sound. Nature 413:474–475
Bremer LGB, Walstra P, von Vilet T (1995) Estimations of the aggregation time of various colloidal systems. Colloids Surf A: Physicochem Eng Aspects 99:121–127
Bremson MA (1968) Infrared radiation: a handbook for applications. Plenum Press, NY
Deegan RD, Bakajin O, Dupont TF, Huber G, Nagel SR, Witten TA (1997) Capillary flow as the cause of ring stains from dried liquids. Nature 389:827–829
Deegan RD, Bakajin O, Dupont TF, Huber G, Nagel SR, Witten TA (2000) Contact line deposits in an evaporating drop. Phys Rev E 62:756–765
Kumar R, Tijerino E, Saha A, Basu S (2010) Structural morphology of acoustically levitated and heated nanosilica droplet. Appl Phys Lett 97:1231061–1231063
Lage PLC, Rangel RH (1993) Single droplet vaporization including thermal radiation absorption. J Thermophys Heat Transf 7:502
Lierke EG, Holitzner L (2008) Perspectives of an acoustic-electrostatic/electrodynamic hybrid levitator for small fluid and solid samples. Meas Sci Technol 19:115803
Mason SG (1977) Orthokinetic phenomena in disperse systems. J Colloid Interf Sci 58:275–285
Omrane A, Santesson S, Aldéna M, Nilsson S (2004) Laser techniques in acoustically levitated micro droplets. Lab Chip 4:287–291
Park B, Armstrong RL (1989) Laser droplet heating: fast and slow heating regimes. Appl Opt 28:3671–3680
Park J, Moon J (2006) Control of colloidal particle deposit patterns within picoliter droplets ejected by ink-jet printing. Langmuir 22:3506–3513
Prasad A, Adrian R, Landreth C, Offutt P (1992) Effect of resolution on the speed and accuracy of particle image velocimetry interrogation. Exp Fluids 13:105–116
Raffel M, Willert C, Kompenhans J (1998) Particle image velocimetry: a practical guide. Verlag, Berlin
Rednikov AY, Zhao H, Sadhal SS, Trinh EH (2006) Steady streaming around a spherical drop displaced from the velocity antinode in an acoustic levitation field. Q J Mech Appl Math 59(3):377–397
Saha A, Basu S, Suryanarayana C, Kumar R (2010) Experimental analysis of thermo-physical processes in acoustically levitated heated droplets. Int J Heat Mass Transf 53:5663–5674
Santiago JG, Wereley ST, Meinhart CD, Beebe DJ, Adrian RJ (1998) A particle image velocimetry system for microfluidics. Exp Fluids 25:316–319
Sazhin SS (2006) Advanced models of fuel droplet heating and evaporation. Prog Energy Combust Sci 32(2):162–214
Sazhin SS, Sazhina EM, Heikal MR (2000) Modelling of the gas to fuel droplets radiative exchange. Fuel 79:1843–1852
Scarano F, Riethmuller ML (1999) Iterative multigrid approach in PIV image processing with discrete window offset. Exp Fluids 26:513–523
Sirignano WA (1999) Fluid dynamics and transport of droplets and sprays. Cambridge University Press, Cambridge
Tian Y, Apfel R (1996) A novel multiple drop levitator for the study of drop arrays. J Aerosol Sci 27:721–737
Trinh E, Wang TG (1982) Large-amplitude free and driven drop-shape oscillations: experimental observations. J Fluid Mech 122:316–338
Wolfe WI, Zissis GJ (1978) The infrared handbook. Office of Naval Research, Department of Navy, Washington DC
Xie J, Wei B (2007) Sound field inside acoustically levitated spherical drop. Appl Phys Lett 90:204104.1–204104.3
Yarin AL, Keller J, Pfaffenlehner M, Ryssel E, Tropea C (1997) Flowfield characteristics of an aerodynamic acoustic levitator. Phys Fluids 9:3300–3314
Yarin A, Pfaffenlehner M, Tropea C (1998) On the acoustic levitation of droplets. J Fluid Mech 356:65–91
Yarin AL, Brenn G, Kastner O, Tropea C (2002) Drying of acoustically levitated droplets of liquid–solid suspensions: evaporation and crust formation. Phys Fluids 14:2289–2298
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The authors wish to acknowledge Mr. Erick Tijerino for the data acquired in Fig. 6.
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Saha, A., Basu, S. & Kumar, R. Particle image velocimetry and infrared thermography in a levitated droplet with nanosilica suspensions. Exp Fluids 52, 795–807 (2012). https://doi.org/10.1007/s00348-011-1114-2
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DOI: https://doi.org/10.1007/s00348-011-1114-2