Numerical studies on channel formation and growth during solidification: Effect of process parameters

Jain, Jayesh and Kumar, Arvind and Dutta, Pradip (2007) Numerical studies on channel formation and growth during solidification: Effect of process parameters. In: Journal of Heat Transfer, 129 (4). pp. 548-558.

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Abstract

In the present work, solidification of a hyper-eutectic ammonium chloride solution in a bottom-cooled cavity (i.e. with stable thermal gradient) is numerically studied. A Rayleigh number based criterion is developed, which determines the conditions favorable for freckles formation. This criterion, when expressed in terms of physical properties and process parameters, yields the condition for plume formation as a function of concentration, liquid fraction, permeability, growth rate of a mushy layer and thermophysical properties. Subsequently, numerical simulations are performed for cases with initial and boundary conditions favoring freckle formation. The effects of parameters, such as cooling rate and initial concentration, on the formation and growth of freckles are investigated. It was found that a high cooling rate produced larger and more defined channels which are retained for a longer durations. Similarly, a lower initial concentration of solute resulted in fewer but more pronounced channels. The number and size of channels are also found to be related to the mushy zone thickness. The trends predicted with regard to the variation of number of channels with time under different process conditions are in accordance with the experimental observations reported in the literature.

Item Type:	Journal Article
Publication:	Journal of Heat Transfer
Publisher:	The American Society of Mechanical Engineers
Additional Information:	Copyright of this article belongs to The American Society of Mechanical Engineers.
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	10 Jun 2010 09:44
Last Modified:	19 Sep 2010 05:58
URI:	http://eprints.iisc.ac.in/id/eprint/26581

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