弱重力场中的平面活塞运动

本文分析了弱重力场中等速活塞运动驱动恒星大气的气体动力学过程.在活塞前面,气体被压缩.压缩气体利用其部分内能,以及有些情况下其动能,以克服外加重力.当逃逸速度与等离子体速度之比值为一小参数时,所有量可对小参数展开,基态解给出均匀流,如同没有重力场的气体动力学所讨论的那样.一阶关系给出外加引力场对流场的影响,即激波强度变化不大而气体内能不断耗散.对于强激波和活塞附近,近似得到的分析解有类似的特征.由于外加重力场在天体物理和大气物理过程中的重要性,这些结果对于恒星和行星大气中瞬变过程的机制会有启发.

The Plane Piston Problem in a Weak Gravitational Field

We analyze a gasdynamical process in the stellar atmosphere that is driven by a "piston" moving with constant velocity in a weak gravitalional field. Ahead of the piston, the gas is compressed, and this compressed gas uses part of its internal energy and somewhere its kinetic energy to overcome the applied gravity.If we expand the quantities as a series of a small parameter, which is the ratio of a typical escape velocity to the plasma velocity, the basic stale gives a uniform flow, as shown by the case of gasdynamical theory without gravity. The first-order relationships show the influence of the applied gravity on the flow fields, that is, the strength of the shock wave changes slightly, the internat energy of the gas exhausts. For the cases of strong shock wave and near the piston, an analytical solution may be approximately olitained and has the similar features.Because of the importance of the applied gravity in the astrophysical and atmospheric physical processes, these results may shed light on the mechanics of transient process in the stellar and planetary atmosphere.