{
  "id": "2408.13087",
  "version": "v1",
  "published": "2024-08-23T14:14:02.000Z",
  "updated": "2024-08-23T14:14:02.000Z",
  "title": "Turbulent convection in emulsions: the Rayleigh-Bénard configuration",
  "authors": [
    "Abbas Moradi Bilondi",
    "Nicolò Scapin",
    "Luca Brandt",
    "Parisa Mirbod"
  ],
  "comment": "Accepted on the Journal of Fluid Mechanics",
  "categories": [
    "physics.flu-dyn"
  ],
  "abstract": "This study explores heat and turbulent modulation in three-dimensional multiphase Rayleigh-B\\'enard convection using direct numerical simulations. Two immiscible fluids with identical reference density undergo systematic variations in dispersed-phase volume fractions, $0.0 \\leq \\Upphi \\leq 0.5$, and ratios of dynamic viscosity, $\\lambda_{\\mu}$, and thermal diffusivity, $\\lambda_{\\alpha}$, within the range $[0.1-10]$. The Rayleigh, Prandtl, Weber, and Froude numbers are held constant at $10^8$, $4$, $6000$, and $1$, respectively. Initially, when both fluids share the same properties, a 10\\% Nusselt number increase is observed at the highest volume fractions. In this case, despite a reduction in turbulent kinetic energy, droplets enhance energy transfer to smaller scales, smaller than those of single-phase flow, promoting local mixing. By varying viscosity ratios, while maintaining a constant Rayleigh number based on the average mixture properties, the global heat transfer rises by approximately 25\\% at $\\Upphi=0.2$ and $\\lambda_{\\mu}=10$. This is attributed to increased small-scale mixing and turbulence in the less viscous carrier phase. In addition, a dispersed phase with higher thermal diffusivity results in a 50\\% reduction in the Nusselt number compared to the single-phase counterpart, owing to faster heat conduction and reduced droplet presence near walls. The study also addresses droplet-size distributions, confirming two distinct ranges dominated by coalescence and breakup with different scaling laws.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-08-23T14:14:02.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "turbulent convection",
      "rayleigh-bénard configuration",
      "reference density undergo systematic variations",
      "identical reference density undergo systematic",
      "droplets enhance energy transfer"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}