标题： 重力波在ZZ Ceti星。 II. 湍流耗散的影响 显示英文标题

标题： Gravity-modes in ZZ Ceti Stars. II. Effects of Turbulent Dissipation

摘要： 我们研究了激变变星（DAVs）中湍流对流与g模脉动之间的动力学相互作用。由于我们对湍流的理解还很初步，我们不得不满足于数量级的结果。这些相互作用的一个关键特征是，对流的响应时间远短于脉动周期。因此，动力学相互作用强制在对流区内部保持几乎均匀的水平速度。它们还在辐射区顶部对流超射区域产生一个狭窄的剪切层。对流区内湍流阻尼对于所有模式来说都可以忽略不计，但在对流超射区域，对于不稳定带红边附近的少数几个长周期模式，这种阻尼可能是显著的。这些结论与Brickhill先前得出的结论一致。我们的主要新结果涉及由上述剪切层的开尔文-亥姆霍兹不稳定性引起的非线性阻尼。过冲模式的振幅饱和，是由于这种不稳定性导致的耗散与对流驱动激发相平衡的地方。这种振幅饱和机制对于长周期模式最为有效，并且可能在定义不稳定带的红边方面发挥重要作用。 显示英文摘要

摘要： We investigate dynamical interactions between turbulent convection and g-mode pulsations in ZZ Ceti variables (DAVs). Since our understanding of turbulence is rudimentary, we are compelled to settle for order of magnitude results. A key feature of these interactions is that convective response times are much shorter than pulsation periods. Thus the dynamical interactions enforce near uniform horizontal velocity inside the convection zone. They also give rise to a narrow shear layer in the region of convective overshoot at the top of the radiative interior. Turbulent damping inside the convection zone is negligible for all modes, but that in the region of convective overshoot may be significant for a few long period modes near the red edge of the instability strip. These conclusions are in accord with those reached earlier by Brickhill. Our major new result concerns nonlinear damping arising from the Kelvin-Helmholtz instability of the aforementioned shear layer. Amplitudes of overstable modes saturate where dissipation due to this instability balances excitation by convective driving. This mechanism of amplitude saturation is most effective for long period modes, and it may play an important role in defining the red edge of the instability strip.