ENERGY CONSERVATION AND GRAVITY WAVES IN SOUND-PROOF TREATMENTS OF STELLAR INTERIORS. PART I. ANELASTIC APPROXIMATIONS
ENERGY CONSERVATION AND GRAVITY WAVES IN SOUND-PROOF TREATMENTS OF STELLAR INTERIORS. PART I. ANELASTIC APPROXIMATIONS
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DOI：
10.1088/0004-637x/756/2/109
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发表时间：
2012-09-10
影响因子：
4.9
通讯作者：
Zweibel, Ellen G.
中科院分区：
文献类型：
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作者：
Brown, Benjamin P.;Vasil, Geoffrey M.;Zweibel, Ellen G.
恒星内部的典型气流比声速慢得多。为了跟踪亚音速运动的缓慢演化，各种隔声方程被广泛使用，特别是在恒星天体物理流体动力学中。这些低马赫数方程包括非弹性方程。一般来说，这些方程在几乎绝热分层的区域，如恒星对流区是有效的，但在次绝热、稳定分层的恒星辐射内部可能不有效。理解对流区和辐射内部之间的耦合是一个至关重要的问题，并且可能对太阳和恒星发电机理论有很强的影响，因为两者之间的界面，称为太阳的速斜，在许多太阳发电机理论中起着至关重要的作用。本文研究了稳定分层大气中重力波的性质。特别是，我们探讨了如何在各种隔音方程中处理重力波。我们发现一些非弹性处理不能在稳定分层的大气中保存能量，而是保存依赖于分层的伪能量，我们用数值证明了这一点。一个非弹性方程集在所有大气中都能保存能量，我们提供了将低马赫数非弹性代码转换为这组方程的建议。
Typical flows in stellar interiors are much slower than the speed of sound. To follow the slow evolution of subsonic motions, various sound-proof equations are in wide use, particularly in stellar astrophysical fluid dynamics. These low-Mach number equations include the anelastic equations. Generally, these equations are valid in nearly adiabatically stratified regions like stellar convection zones, but may not be valid in the sub-adiabatic, stably stratified stellar radiative interiors. Understanding the coupling between the convection zone and the radiative interior is a problem of crucial interest and may have strong implications for solar and stellar dynamo theories as the interface between the two, called the tachocline in the Sun, plays a crucial role in many solar dynamo theories. Here, we study the properties of gravity waves in stably stratified atmospheres. In particular, we explore how gravity waves are handled in various sound-proof equations. We find that some anelastic treatments fail to conserve energy in stably stratified atmospheres, instead conserving pseudo-energies that depend on the stratification, and we demonstrate this numerically. One anelastic equation set does conserve energy in all atmospheres and we provide recommendations for converting low-Mach number anelastic codes to this set of equations.