Modeling fluid flow in three-dimensional single crystal dendritic structures

作者：Madison J^*; Spowart J; Rowenhorst D; Aagesen L K; Thornton K; Pollock T M

来源：Acta Materialia, 2010, 58(8): 2864-2875.

DOI：10.1016/j.actamat.2010.01.014

• Nickel alloys
• Dendritic growth
• Directional solidification
• Modeling
• Permeability

Convection during directional solidification can cause defects such as freckles and misoriented grains To gain a better understanding of conditions associated with the onset of convective instabilities, flow was investigated using three-dimensional (3D) computational fluid dynamics simulations in an experimentally obtained dendritic network A serial-sectioned, 3D data set of directionally solidified nickel-base superalloy measuring 2 3 x 2 3 x 15 mm was used to determine the permeability for flow parallel and normal to the solidification direction as a function of solid fraction (f(S)) Anisotropy of permeability varies significantly from 0 4 < f(S) < 0 6 High flow velocity channels exhibit spacings commensurate with primary dendrite arms at the base of the mushy zone but rapidly increase by a factor of three to four towards dendrite tips Permeability is strongly dependent on interfacial surface area, which reaches a maximum at f(S) = 0 65 Results from the 3D simulation are also compared with empirical permeability models, and the microstructural origins of departures from these models are discussed.

• 出版日期2010-5
• 单位西北大学