论文标题
稀释单变性气体的散装粘度
Bulk viscosity of dilute monatomic gases
论文作者
论文摘要
过去已经进行了广泛的研究，以估计密集的单变性流体的块状粘度。但是，在稀释的气体制度中，很少有人注意估计相同的估计。在这项工作中，我们在分子动力学模拟中执行精确的绿色kubo计算，以估计稀氩气的大量粘度。研究的温度和压力范围分别为300至750 K和0.5至1.5 bar。可以观察到估计的散装粘度为$ O（10^{ - 10}）$ pa s，它比其他硅藻和多原子气体小的几个数量级小，但是尽管如此，但不是通常假设的绝对零。这意味着斯托克斯的假设对于稀释的单原子气体仅在近似而不是绝对意义上才是正确的。还研究了在恒定温度下与压力的体积粘度的变化，并且被发现具有二次性质。在降低的Lennard-Jones单位中，还报告了所获得的大量粘度值，以使本结果也可以扩展到其他贵重气体。还观察到，Lennard-Jones美色气体的大量粘度在非常低的密度下独立于温度。
Extensive research has been carried out in the past to estimate the bulk viscosity of dense monatomic fluids; however, little attention has been paid to estimate the same in the dilute gas regime. In this work, we perform precise Green-Kubo calculations in molecular dynamics simulations to estimate the bulk viscosity of dilute argon gas. The investigated temperature and pressure range is 300 to 750 K and 0.5 to 1.5 bar respectively. It is observed that the estimated bulk viscosity is $O(10^{-10})$ Pa s, which is several orders of magnitude smaller than that of other diatomic and polyatomic gases, but nonetheless, not an absolute zero as typically assumed. It implies that Stokes' hypothesis is true for dilute monatomic gases only in an approximate rather than absolute sense. The variation of bulk viscosity with pressures at constant temperatures has also been studied and is found to be of quadratic nature. The obtained bulk viscosity values are also reported in the reduced Lennard-Jones units to enable extension of the present results to other noble gases as well. It has also been observed that the bulk viscosity of Lennard-Jones monatomic gases becomes temperature independent at very low densities.
