中文摘要：

应用一个二维的元胞自动机（cellular automata,CA）-格子玻尔兹曼方法（lattice Boltz-mann method,LBM）耦合模型,对合金等温凝固过程中溶质枝晶在强制对流作用下的生长规律进行了模拟研究.该耦合模型采用CA方法模拟枝晶生长,同时采用基于分子动理论的LBM模拟枝晶生长过程中的流场和浓度场.应用该模型模拟分析了过冷度和成分等因素对Al-Cu合金在纯扩散和对流作用下单枝晶的生长规律的影响.结果表明,在纯扩散条件下,模拟的枝晶稳态生长尖端速度、半径、Peclet数和过冷度的关系与Lipton-Glicksman-Kurz（LGK）模型的预测结果吻合良好.对流作用下枝晶的生长形貌呈现出了不对称性,枝晶的生长在上游方向得到促进,而在下游方向受到抑制.合金成分和初始过冷度等因素会对枝晶形貌和生长动力学产生影响.

英文摘要：

A two-dimensional （2D） cellular automaton-lattice Boltzmann （CA-LBM） model was employed to simulate the dendritic growth in the presence of forced convection during isothermal solidification of binary alloys. In the model, the dendritic growth is simulated by a CA approach, and the flow field and the concentration field are numerically solved using the LBM based on the gas kinetic theory. The model was applied to simulate the single dendritic growth of Al-Cu alloys in the cases of pure diffusion and melt convection. The effects of undercooling and alloy composition on the convective dendritic morphology were investigated. The results show that the simulated pure diffusive dendritic steady-state growth tip velocity, radius and Peclet number with various undercoolings are in reasonable agreement with the predictions of the Lipton-Glicksman-Kurz（LGK） model. With melt convection, the tip velocity is enhanced in the upstream region and inhibited in the downstream region, resulting in the typical asymmetric growth features of convective dendrite. It is also found that the initial compositions and the initial undercooling may influence the dendritic morphology and growth dynamics.