Sensitivity of mesh spacing on simulating macrosegregation during directional solidification of a superalloy

P. K. Sung, D. R. Poirier, S. D. Felicelli

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

The sensitivity of mesh spacing on simulations of macrosegregation, particularly 'freckles', during vertical directional solidification of a superalloy in a rectangular mold was systematically analyzed to achieve accurate predictions in finite element calculations. It was observed that a coarser mesh spacing in the x-direction horizontal tends to minimize the simulated macrosegregation, whereas a coarser mesh spacing in the y-direction vertical artificially tends to make the system appear to have more macrosegregation. When solidification conditions either lead to a well-established freckling case or to a well-established non-freckling case, the simulated results are not sensitive to the mesh spacing provided the elements are no larger than about 2d1 by 2 D/V and 3d1 by 4 D/V respectively, where d1 is the primary dendrite arm spacing, D is the diffusivity of the alloy solute with the smallest diffusivity in the liquid, and V is the growth rate. However, when solidification conditions are very close to the transition between freckling and no freckling, the simulated results are sensitive to the mesh spacing, especially in the y-direction. Based on the mesh sensitivity analysis from the two-dimensional simulations of rectangular castings of Rene N5, the mesh with element dimensions no larger than 2d1 in the x-direction and 1.5 D/V in the y-direction are recommended as the most stringent element size.

Original languageEnglish (US)
Pages (from-to)357-370
Number of pages14
JournalInternational Journal for Numerical Methods in Fluids
Volume35
Issue number3
DOIs
StatePublished - Feb 15 2001

Keywords

  • Dendritic single crystal
  • Directional solidification
  • Freckles
  • Macrosegregation
  • Mesh spacing

ASJC Scopus subject areas

  • Computational Mechanics
  • Mechanics of Materials
  • Mechanical Engineering
  • Computer Science Applications
  • Applied Mathematics

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