We propose a new theory of second-order viscous relativistic hydrodynamics which does not impose any frame conditions on the choice of the hydrodynamic variables. It differs from Mueller-Israel-Stewart theory by including additional transient degrees of freedom, and its first-order truncation reduces to Bemfica-Disconzi-Noronha-Kovtun theory. Conditions for causality and stability are explicitly given in the conformal regime. As an illustrative example, we consider Bjorken flow solutions to our equations and identify variables which make a hydrodynamic attractor manifest.

中文翻译：

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一般流体力学框架中的瞬态相对论流体动力学

我们提出了一种二阶粘性相对论流体动力学的新理论，该理论不对流体动力学变量的选择施加任何框架条件。它与 Mueller-Israel-Stewart 理论的不同之处在于包含额外的瞬态自由度，并且其一阶截断简化为 Bemfica-Disconzi-Noronha-Kovtun 理论。因果关系和稳定性的条件在保形机制中明确给出。作为一个说明性示例，我们考虑方程的 Bjorken 流动解，并确定使流体动力吸引子显现的变量。