相场法模拟对流速度对上游枝晶生长的影响

基于Tong和Beckermann等提出的耦合流场的相场模型，采用有限差分法对纯金属凝固过程进行二维模拟计算，研究了不同对流速度对金属枝晶生长的影响.结果表明：在有对流情况下，上游及下游枝晶呈现不对称形貌，上游枝晶生长速度明显比下游方向生长速度快.随着对流速度的增大，上游尖端过冷度也增大，枝晶生长也越快.这是由于流体速度越大，对上游枝晶冲刷越强，上游枝晶尖端实际过冷度越大，枝晶生长越迅速. 关键词： 相场法 对流速度 上游枝晶

Simulation of the influence of convection velocity on upstream dendritic growth using phase-field method

The phase-field model based on the Tong and Beckermann model coupled with the flow field is used to simulate two-dimensional microstructural dendrite growth of metal by way of finite difference method. The effect of different convection velocities on metal dendritic crystal growth is studied. The result shows that the upstream and downstream dendritic crystal present asymetric pattern: the growth velocity of upstream is much fasfer than downstream. As the velocity of convection increases，actual supercooling of upstream dendritic crystal increases，the growth velocity of dendritic crystalis also speeded up. This is because of the bigger convection velocity leads to stronger flushing to the upstream dendritic crystal and the greater actual supercooling of upstream dendritic crystal，making the dendritic crystal to grow faster.