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Evolutionary structures in double‐diffusive convection in magma chambers
Author(s) -
Hansen Ulrich,
Yuen David A.
Publication year - 1987
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl014i011p01099
Subject(s) - convection , thermal diffusivity , double diffusive convection , prandtl number , magma , lewis number , thermal , geophysics , geology , mechanics , thermodynamics , physics , natural convection , rayleigh number , volcano , seismology , mass transfer
Finite‐amplitude solutions to subcritical, time‐dependent, double‐diffusive convection (D.D.C.) applicable for magma chambers are obtained by a two‐dimensional, finite‐element method based on stream‐function, temperature and compositional fields. Grid‐refinement is used for resolving the disparately‐scaled thermal and chemical boundary layers present for large ratios of the thermal to chemical diffusivity (Lewis number) characteristic of magmas. The occurrence of layered convection depends strongly on the initial conditions of the temperature and composition. It is shown that in the infinite Prandtl number limit a local transition from a diffusive to a finger‐like regime can take place for large enough Lewis numbers. This time‐dependent finding suggests that a strict categorization of D.D.C. into the finger and diffusive regimes requires modification in geological applications.