Dendritic solidification under natural and forced convection in binary alloys: 2D versus 3D simulation
Dendritic solidification under natural and forced convection in binary alloys: 2D versus 3D simulation
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DOI：
10.1088/0965-0393/18/5/055008
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发表时间：
2010-07-01
影响因子：
1.8
通讯作者：
Lee, Peter D.
中科院分区：
文献类型：
--
作者：
Yuan, Lang;Lee, Peter D.
开发了等轴和柱状树突生长模型，该模型结合了二维或三维的热、溶质和流体流动效应。该模型求解动量、质量和能量传输方程，包括相变。强加的各向异性算法与纳维-斯托克斯方程的修正投影法解相结合，允许相对粗糙的网格，因此具有出色的计算效率。该模型用于研究维度（2D 与 3D）对有对流和无对流的树突生长的影响。首先研究了强制对流对无约束等轴生长的影响。在 3D 中，上游边界层比 2D 中要薄得多，浓度也更低。这会增加尖端过冷，加速上游尖端生长并促进二次分枝。然后研究了自然对流对受限柱状枝晶生长的影响。 2D 流被初级枝晶臂（实际上是板）阻挡，而 3D 流可以环绕初级枝晶臂。这种流动的变化强烈改变了溶质的分布，从而改变了枝晶微观结构的发展。需要进行 3D 模拟才能正确预测无约束凝固微观结构。
A model of both equiaxed and columnar dendritic growth was developed that incorporates thermal, solutal and fluid flow effects in either two or three dimensions. The model solves the momentum, mass and energy transport equations, including phase change. An imposed anisotropy algorithm, combined with a modified projection method solution of the Navier-Stokes equations, allows a relative coarse mesh and hence excellent computational efficiency. The model was used to study the effect of dimensionality (2D versus 3D) on dendritic growth with and without convection. The influence of forced convection on unconstrained equiaxed growth was studied first. In 3D, the upstream boundary layer is much thinner with a lower concentration than in 2D. This increases tip undercooling, accelerating upstream tip growth and promoting secondary branching. The influence of natural convection on constrained, columnar dendritic, growth was then studied. The 2D flow is blocked by the primary dendrite arms (which are effectively plates), while the 3D flow can wrap around the primaries. This change in flow strongly alters solute distribution and consequently the developing dendritic microstructure. 3D simulations are required to correctly predict unconstrained solidification microstructures.