Abstract The Boltzmann equation is solved in the relaxation time approximation using a hierarchy of angular moments of the distribution function. Our solution is obtained for an azimuthally symmetric radially expanding boost-invariant conformal system that is undergoing Gubser flow. The solution of moments that we get after truncating the infinite set of equations at various orders is compared to the exact kinetic solution. The dynamics of transition is described by the presence of fixed points which describes the evolution of the system from an early time collisionless free streaming to the hydrodynamic regime at intermediate times and back to free streaming at late times. The attractor solution is found for various orders of moments as an interpolation between these fixed points. The relation of moments to various approximations of relativistic viscous hydrodynamics is investigated.

中文翻译：

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用于 Gubser 流的流体动力吸引子

摘要 玻尔兹曼方程使用分布函数的角矩层次在弛豫时间近似中求解。我们的解决方案是针对正在经历 Gubser 流的方位角对称径向扩展升压不变共形系统获得的。我们将在不同阶数上截断无限方程组后得到的矩解与精确动力学解进行比较。过渡的动力学通过固定点的存在来描述，固定点描述了系统从早期无碰撞自由流动到中间时间的流体动力学状态以及后期回到自由流动的演变。对于不同阶矩的吸引子解是这些固定点之间的插值。