惰性多原子气体中数值bow shock不稳定性研究
Numerical Bow Shock Instabilities in Inert Polyatomic Gases
AI总结：
研究低比热比气体中轴对称流过超音速球体时出现的无粘性数值不稳定性，发现高密度比和粗网格会导致carbuncle型波动不稳定性，强调需区分真实物理不稳定性与数值伪影。
摘要：
我们研究了在惰性、 calorically perfect气体中模拟轴对称流过超音速球体时出现的无粘性数值不稳定性。我们证明当密度比较高且计算网格较粗时，在接触面上靠近滞止点的激波层中会发展出数值诱导的traveling-wave不稳定性，即carbuncle型。这些未在文献中记录的不稳定性值得注意，因为在多原子气体中，post-shock thermochemical relaxation也会观察到激波振荡。当此类气体被建模为惰性且具有有效低γ时，我们的结果强调需谨慎以避免将真实物理不稳定性与模拟中的数值伪影混淆。
英文摘要：
We investigate inviscid numerical instabilities that arise in simulations of axisymmetric flow over a hypersonic sphere in an inert, calorically perfect gas at low specific heat ratio ($γ\approx 1.1$--$1.2$). We show that when the density ratio across the bow shock is high and the computational mesh is relatively coarse, numerically induced traveling-wave instabilities of the carbuncle type can develop in the shock layer near stagnation for inert gases. These instabilities, not previously documented in the literature, are noteworthy because bow shock oscillations are also observed experimentally in polyatomic gases exhibiting post-shock thermochemical relaxation. When such gases are modeled as inert with an effectively low $γ$, our results emphasize the need for caution to avoid conflating genuine physical instabilities with numerical artifacts in simulations.
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