Simple modification techniques are proposed for making numerical fluxes amenable to unrealizable states (e.g., negative density) without degrading the design order of accuracy, so that a finite-volume solver never fails with unrealizable states arising in the solution reconstruction step and continues to run. The main idea is to evaluate quantities not affecting the order of accuracy but important for stabilization, e.g., a dissipation matrix, with low-order unreconstructed solutions. For the viscous flux, the viscosity is linearly extrapolated instead of being evaluated with linearly reconstructed temperatures to avoid a failure with a negative temperature. These ideas are quite general and may be applied to a wide range of numerical fluxes. In this paper, we illustrate them with the Roe flux and the alpha-damping viscous flux and demonstrate their effectiveness for cases, where a conventional technique encounters difficulties.

提出了简单的修改技术，以使数值通量适应不可实现的状态（例如，负密度），而不会降低设计精度，因此有限体积的求解器永远不会因在解决方案重构步骤中出现不可实现的状态而失败并继续运行。主要思想是使用低阶未重构解来评估不影响精度顺序但对稳定很重要的量，例如耗散矩阵。对于粘性通量，粘度是线性外推的，而不是使用线性重构温度来评估的，以避免出现负温度故障。这些想法非常笼统，可应用于各种数值通量。在本文中，