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Sensitivity of mesh spacing on simulating macrosegregation during directional solidification of a superalloy
Author(s) -
Sung P. K.,
Poirier D. R.,
Felicelli S. D.
Publication year - 2001
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/1097-0363(20010215)35:3<357::aid-fld99>3.0.co;2-9
Subject(s) - superalloy , directional solidification , thermal diffusivity , materials science , finite element method , mechanics , sensitivity (control systems) , mass diffusivity , slab , alloy , composite material , physics , structural engineering , thermodynamics , engineering , electronic engineering
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 2 d 1 by 2 D / V and 3 d 1 by 4 D / V respectively, where d 1 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 René N5, the mesh with element dimensions no larger than 2 d 1 in the x ‐direction and 1.5 D / V in the y ‐direction are recommended as the most stringent element size. Copyright © 2001 John Wiley & Sons, Ltd.