{
  "abstract": "We perform 3D hydrodynamic simulations of two idealized convection setups: a cooling-driven model (Model C) and an entropy-gradient-driven model (Model S). The two setups exhibit clear differences: while Model S develops large, relatively stationary eddies excited at depth, Model C is dominated near the surface by intermittent plume-like downflows that produce broad non-Gaussian velocity distributions and a turbulent energy flux that exceeds that in Model S by nearly an order of magnitude in the upper convection zone. Conventional gradient-diffusion (GD) closures reproduce the transport in Model S but significantly underestimate it in Model C, demonstrating that the plume-dominated transport realized in our cooling-driven setup cannot be reproduced by a local, gradient-based model. To address this, we introduce a time-space double averaging method that extracts coherent fluctuations, yielding a diagnostic variable $\\tilde{\\boldsymbol {u}}$ that peaks where the flux is largest. Building on this insight, we propose a modified GD closure in which the turbulent diffusivity is corrected by a plume-mediated term, achieving quantitative agreement with simulation results. Although the closure requires a calibrated model parameter and a careful choice of the averaging window, it provides a physically transparent framework that links coherent plume dynamics to mean-field transport and offers a pathway toward improved subgrid models for non-equilibrium stellar convection zones.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Applied Physics, Faculty of Science, Fukuoka University , Fukuoka 814-0180 ,",
    "Division of Science, National Astronomical Observatory of Japan (NAOJ) , Osawa, Mitaka, Tokyo 181-8588 ,",
    "Institute of Industrial Science, University of Tokyo , Komaba, Meguro, Tokyo 153-8505 ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Youhei Masada"
    },
    {
      "affs": [
        1
      ],
      "name": "Tomoya Takiwaki"
    },
    {
      "affs": [
        2
      ],
      "name": "Nobumitsu Yokoi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/21fngmwmrd88c.bib",
  "cited_by": 0,
  "doi": "10.1093/mnras/stag1988",
  "fulltext_url": null,
  "id": "21fngmwmrd88c",
  "issns": [
    "0035-8711",
    "1365-2966"
  ],
  "landing_url": "https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1988/8965441",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W4416378479",
  "pdf_url": "https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag1988/72259374/stag1988.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": "Oxford University Press (OUP)",
  "ris": "https://research.draconitic.com/paper/21fngmwmrd88c.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:17Z",
      "native_id": "10.1093/mnras/stag1988",
      "source": "crossref",
      "url": "https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1988/8965441"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Stellar, planetary, and galactic studies",
      "subfield": "stellar"
    }
  ],
  "title": "Modelling stellar convective transport with plumes – II. Transport properties of locally and non-locally driven convection",
  "title_text": "Modelling stellar convective transport with plumes – II. Transport properties of locally and non-locally driven convection",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:17Z",
  "url": "https://research.draconitic.com/paper/21fngmwmrd88c",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": []
}