用Boltzmann方程矩的合理选择封闭各向异性流体动力学的运动方程
Closing the equations of motion of anisotropic fluid dynamics by a judicious choice of moment of the Boltzmann equation
摘要：
在Molnár等人[Phys. Rev. D 93，114025（2016）]中，各向异性耗散流体动力学的方程是根据基于任意各向异性单粒子分布函数展开的玻尔兹曼方程的矩获得的。在本文中，我们作出了特别的选择，这个分布函数，并考虑在一维流体的升压不变的膨胀。为了封闭守恒方程，我们需要选择玻尔兹曼方程的附加矩。我们讨论了这一时刻的选择对流体动力学变量的时间演化的影响，并确定的时刻，提供了最佳匹配的各向异性流体动力学的Boltzmann方程的松弛时间近似的解决方案。
英文摘要：
In Molnár et al. [Phys. Rev. D 93, 114025 (2016)] the equations of anisotropic dissipative fluid dynamics were obtained from the moments of the Boltzmann equation based on an expansion around an arbitrary anisotropic single-particle distribution function. In this paper we make a particular choice for this distribution function and consider the boost-invariant expansion of a fluid in one dimension. In order to close the conservation equations, we need to choose an additional moment of the Boltzmann equation. We discuss the influence of the choice of this moment on the time evolution of fluid-dynamical variables and identify the moment that provides the best match of anisotropic fluid dynamics to the solution of the Boltzmann equation in the relaxation-time approximation.
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