在激光材料加热中,由于存在着表面张力驱动的流动,熔池表面附近熔体的速度梯度很大.为了更好地研究熔池里的流动,对该速度变化急剧的表面层区域和其余区域分开进行求解并相互耦合.将该计算结果与把熔池作为一个整体求解所得结果进行比较表明,只要表面附近网格分得足够细密,整体进行求解也可以得到准确的结果.

A thin surface layer always exists near the surface of laser heating melt pool due to the fluid flow driven by the surface tension gradient. In order to simulate accurately the fluid flow in the laser heating melt pool, the influence of the thin surface layer must be considered carefully. In this paper, the computational domain is divided into two regions, region I includes most part of the melt pool except for the thin surface layer on the top of the melt pool, i.e. region II . Comparison of simulated results using the two-region method with those using single-region method shows that one still can employ the single-region modeling approach to obtain correct isotherms and flow fields provided the mesh near the upper boundary is fine enough to resolve the surface layer.