液态锂在铜的微通道中的流动行为

本文采用分子动力学方法模拟了液态锂在铜的微通道内的流动行为. 通过构建铜(111), (100)和(110)晶面的微通道内壁, 研究了液态锂在流固界面上的微观结构以及在铜微通道中的流动速度分布情况, 并探讨了微通道尺寸对液态锂流动行为的影响. 研究结果表明铜微通道内的液态锂在靠近铜固体壁附近区域呈有序的层状结构分布, 并受铜内壁晶面微观结构的影响. 铜(111)和(100)面内壁附近的液态锂有序层分布结构更明显. 外驱力作用下的液态锂在微通道内的流动速度呈抛物线分布, 流固界面和流动方向对液态锂的流动速度都会产生影响. 液态锂在铜(111)面内壁上流动的速度最大, 且出现了速度滑移; 在铜(110)面内壁上流动速度最小. 通过对不同尺寸的微通道内液态锂流动行为的研究, 发现流动速度的大小随着微通道尺寸的增加而增大, 且最大速度与微通道尺寸呈二次函数关系, 与有关理论计算结果符合得很好.

The flow behavior of liquid Li in Cu micro-channels

The flow properties of liquid in microchannel have received more attention for their wide applications in different fields. Up to now, little work has focused on the flow behaviors of liquid metals. Recently, liquid lithium (Li) has been considered as one of the candidate plasma-facing materials (PFMs) because of its excellent properties in fusion reactor applications. Considering an accident condition, liquid Li may contact Cu components and erode them, which may cause a serious disaster. The study of the flow properites of liquid Li in Cu microchannel is crucial for the safe application of liquid Li working as a PFM. With the method of non-equilibrium molecular dynamics simulations, in this paper we investigate the flow behavior of liquid Li flowing in Cu microchannels. The density and velocity distributions of Li atoms are obtained. The influence of the dimension of Cu microchannel on the flowing behavior of liquid Li is studied. Comparative analyses are made in three different fluid-solid interfaces, i.e., Li-Cu(100), Li-Cu(110) and Li-Cu(111), respectively. Results show that the density distributions of liquid Li near the interface present an orderly stratified structure. Affected by a larger surface density, a more obviously stratification is found when Li atoms are near the fluid-solid interfaces of Li-Cu(100) and Li-Cu(111) and a wider vacuum gap appears between Li atoms and Cu(111) interface. When Li atoms are near the Li-Cu(110) interface, a lower stratification can be found and an alloy layer appears at Li-Cu(110) interface. Because of its lower surface density, Li atoms spread into the bulk Cu more easily. However, the density distributions have little difference when Li atoms are close to the same fluid-solid interface but with different flow directions. The velocity of Li atoms in microchannel has a parabolic distribution. Because there exists a wider vacuum gap and stratified structure, the Li atoms closed to the Li-Cu (111) interface have the largest velocity. Closed to the Li-Cu (110) interface, Li atoms have the smallest velocity because of the alloy layer and the lower stratified structure. Owing to the diversity of the atomic configurations of Cu (110) face, the liquid Li atoms flow with diverse velocities in different directions on the Li-Cu (110) interface. It is also found that the magnitude of flowing velocity of liquid Li is proportional to the square of microchannel dimension and increases with it. When liquid Li is flowing on the Li-Cu(100) interface, the simulation result reveals that the relationship between microchannel dimension and the largest velocity of Li atoms is in good agreement with Navier-Stokes theory result. It is noteweathy that the present result is smaller than the theoretical result when a “negative slip” occurs at the Li-Cu(110) interface. In contrast, the result is greater than the theoretical result in the presence of a “positive slip” at Li-Cu(111) interface.