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Title:Onset of thermal-chemical convection with crystallization within a binary fluid and its geological implication
Author(s):Hsui, Albert T.; Riahi, Daniel N.
Subject(s):Thermal-chemical Convection
Binary Fluid
Abstract:A model to study the onset of stability of a thermal-chemical system with crystallization was developed. A theory based on a small perturbation to an ordinary double diffusive system was used for the analysis. Our results show that. in the presence of crystal precipitation, the slope of a dynamic stability boundary is no longer governed by a ratio between the thermal diffusion coefficient and the compositional diffusion coefficient alone. The release of latent heat due to solidification and the location of crystallization also play important roles. [n addition, the oscillatory convective region is not confined wi thin the positive compositional Rayleigh number domain as in an ordinary double diffusive system. It can extend into the negative compositional Rayleigh number regime as well. How far 1t can extend into the unstable regime is dependent upon many parameters including the latent heat release associated with crystallization. On the basis of a thermal and compositional buoyancy an:ilysis, it is found that double diffusive layering remains a possibility within a solidifying tholeiitic magma body. However. it is not the authors' intention to use this study to prove or disprove if double diffusion is the origin of the observed igneous layering in Skaegaard, for example. If intrusive layering is rare in calc-alkaline magma bodies and if double-diffusive dynamics operate within these magma bodies. solidification of calc-alkJline magma must operate within the upper left comer of the first quadrant of the stability diagram. Otherwise, layering must be more prominent in calc-alkaline magmas. As to the outer liquid core, solidification above the inner-outer core boundary can produce layering structure only under very special conditions. Unless these appropriate conditions exist, other dynamic processes may be more probable in producing the seismically observed layers within the inner core. Solidification beneath the core-mantle boundary. on the other hand, may produce stabilizing layers that act to inhibit large-scale convection near the top of the liquid outer core.
Issue Date:2000-04
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 935
Genre:Technical Report
Rights Information:Copyright 2000 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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