Velocity distribution function of spontaneously evaporating atoms
Velocity distribution function of spontaneously evaporating atoms
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DOI：
10.1103/physrevfluids.5.103401
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发表时间：
2020-10-12
影响因子：
2.7
通讯作者：
Sprittles, James E.
中科院分区：
文献类型：
--
作者：
Busuioc, Sergiu;Gibelli, Livio;Sprittles, James E.
利用Enskog-Vlasov方程的数值解确定了原子自发蒸发到近真空条件下的速度分布函数。结果表明，对于垂直于汽液界面和平行于汽液界面的速度分量，考虑漂移速度和不同特征温度的半麦克斯韦近似提供了一个精确的近似。漂移速度和温度各向异性随着液体整体温度的降低而减小，但在相对较低的温度下保持不变，对应的是蒸汽行为，这只是轻微的非理想行为。偏离未漂移的各向同性半麦克斯韦模型是气液界面碰撞的结果，气液界面优先后向散射具有较低法向速度分量的原子。
Numerical solutions of the Enskog-Vlasov equation are used to determine the velocity distribution function of atoms spontaneously evaporating into near-vacuum conditions. It is found that an accurate approximation is provided by a half-Maxwellian including a drift velocity combined with different characteristic temperatures for the velocity components normal and parallel to the liquid-vapor interface. The drift velocity and the temperature anisotropy reduce as the liquid bulk temperature decreases but persist for relatively low temperatures corresponding to a vapor behavior which is only slightly nonideal. Deviations from the undrifted isotropic half-Maxwellian are shown to be consequences of collisions in the liquid-vapor interface which preferentially backscatter atoms with lower normal-velocity component.