Buoyant Convection in Dendritic Solidification
Abstract
In solidification, when the process is limited by diffusion of released latent heat or solute, often the two-phase interface forms finger-like shapes called dendrites, whose tips are nearly paraboloidal in form. For a pure material solidifying into an undercooled melt, if surface energy and gravity are negligible, a well-known solution due to Ivantsov (1947) describes the steady growth with a paraboloidal interface. We construct a regular perturbation to this solution for a downward growing axisymmetric dendrite, based on the smallness of a buoyancy parameter G, to examine the effects of buoyant flow on the solidification. The analytic solution predicts that generally the buoyancy enhances growth and changes the shape of the interface, giving a sharper tip and wider base. These effects depend strongly on the Prandtl number, and also on the Stefan number (undercooling). The results compare will with the experiments of Huang and Glicksman (1981) up to G 5000, but over predict convective effects for higher G.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 04, 1990
- Accession Number
- ADA221599
Entities
People
- David Canright
- S. H. Davis
Organizations
- Naval Postgraduate School