The dynamics of an insulating plate over a thermally convecting fluid and its implication for continent movement over convective mantle

Yadan Mao, Jin Qiang Zhong, Jun Zhang

Research output: Contribution to journalArticle

Abstract

Continents exert a thermal blanket effect to the mantle underneath by locally accumulating heat and modifying the flow structures, which in turn affects continent motion. This dynamic feedback is studied numerically with a simplified model of an insulating plate over a thermally convecting fluid with infinite Prandtl number at Rayleigh numbers of the order of . Several plate-fluid coupling modes are revealed as the plate size varies. In particular, small plates show long durations of stagnancy over cold downwellings. Between long stagnancies, bursts of velocity are observed when the plate rides on a single convection cell. As plate size increases, the coupled system transitions to another type of short-lived stagnancy, in which case hot plumes develop underneath. For an even larger plate, a unidirectional moving mode emerges as the plate modifies impeding flow structures it encounters while maintaining a single convection cell underneath. These identified modes are reminiscent of some real cases of continent-mantle coupling. Results show that the capability of a plate to overcome impeding flow structures increases with plate size, Rayleigh number and intensity of internal heating. Compared to cases with a fixed plate, cases with a freely drifting plate are associated with higher Nusselt number and more convection cells within the flow domain.

Original languageEnglish (US)
Pages (from-to)286-315
Number of pages30
JournalJOURNAL OF FLUID MECHANICS
Volume868
DOIs
StatePublished - Jun 10 2019

Fingerprint

Flow structure
continents
Earth mantle
Fluids
fluids
Prandtl number
Nusselt number
convection cells
Feedback
Heating
Rayleigh number
Convection
Hot Temperature
blankets
encounters
coupled modes
plumes
bursts
heat

Keywords

  • convection in cavities
  • mantle convection

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

The dynamics of an insulating plate over a thermally convecting fluid and its implication for continent movement over convective mantle. / Mao, Yadan; Zhong, Jin Qiang; Zhang, Jun.

In: JOURNAL OF FLUID MECHANICS, Vol. 868, 10.06.2019, p. 286-315.

Research output: Contribution to journalArticle

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N2 - Continents exert a thermal blanket effect to the mantle underneath by locally accumulating heat and modifying the flow structures, which in turn affects continent motion. This dynamic feedback is studied numerically with a simplified model of an insulating plate over a thermally convecting fluid with infinite Prandtl number at Rayleigh numbers of the order of . Several plate-fluid coupling modes are revealed as the plate size varies. In particular, small plates show long durations of stagnancy over cold downwellings. Between long stagnancies, bursts of velocity are observed when the plate rides on a single convection cell. As plate size increases, the coupled system transitions to another type of short-lived stagnancy, in which case hot plumes develop underneath. For an even larger plate, a unidirectional moving mode emerges as the plate modifies impeding flow structures it encounters while maintaining a single convection cell underneath. These identified modes are reminiscent of some real cases of continent-mantle coupling. Results show that the capability of a plate to overcome impeding flow structures increases with plate size, Rayleigh number and intensity of internal heating. Compared to cases with a fixed plate, cases with a freely drifting plate are associated with higher Nusselt number and more convection cells within the flow domain.

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