Enhanced heat flux in vertical natural convection by droplet-induced turbulence

ORAL

Abstract

Bubbles are typically used in engineering applications to promote mixing or to enhance heat transport. Using direct numerical simulations with immersed boundaries, we show that light rising droplets enhance the volume-averaged heat flux in vertical natural convection for Rayleigh numbers within one decade in separation and Prandtl number of 7. Specifically, we find that the heat flux can be manipulated by changing the volume fraction occupied by the droplets and the ratio of droplet density to fluid density. The underlying mechanism can be linked to the strength of droplet-induced turbulence, which can be quantified by the ratio of droplet buoyancy to the thermal buoyancy of vertical natural convection.

*This work is part of the research programme of the Foundation for Fundamental Research on Matter (FOM), which is financially supported by the Netherlands Organisation for Scientific Research (NWO).

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Presenters

  • Chong Shen Ng

    • Univ of Twente

Authors

  • Chong Shen Ng

    • Univ of Twente

  • Vamsi Spandan

    • University of Twente
    • Harvard University

  • Detlef Lohse

    • University of Twente
    • Physics of Fluids and Max Planck Center for Complex Fluids Dynamics, University of Twente, Enschede, The Netherlands
    • Univ of Twente
    • Univ of Twente, Max Plank Institute for Dynamics and Self-Organization
    • Twente Tech Univ
    • University of Twente, Max Planck Center for complex fluid dynamics

  • Roberto Verzicco

    • Univ of Roma
    • University of Rome
    • Università di Roma Tor Vergata, PoF University of Twente
    • Univ of Roma Tor Vergata, Univ. of Twente
    • University of Roma
    • Univ of Roma "Tor Vergata"
    • University of Roma, University of Twente
    • Univ of Twente, Univ of Rome 'Tor Vergata'