Żuk Paweł J, Makuch Karol, Hołyst Robert, Maciołek Anna
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw, Poland.
Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom.
Phys Rev E. 2022 May;105(5-1):054133. doi: 10.1103/PhysRevE.105.054133.
We investigate the thermal relaxation of an ideal gas from a nonequilibrium stationary state. The gas is enclosed between two walls, which initially have different temperatures. After making one of the walls adiabatic, the system returns to equilibrium. We notice two distinct modes of heat transport and associated timescales: one connected with a traveling heat front and the other with internal energy diffusion. At the heat front, which moves at the speed of sound, pressure, temperature, and density change abruptly, leaving lower values behind. This is unlike a shock wave, a sound wave, or a thermal wave. The front moves multiple times between the walls and is the dominant heat transport mode until surpassed by diffusion. We found that it can constitute an order 1 factor in shaping the dynamics of the outflow of internal energy. We found that cooling such a system is quicker than heating, and that hotter bodies cool down quicker than colder ones. The latter is known as the Mpemba effect.
我们研究了理想气体从非平衡稳态的热弛豫过程。气体被封闭在两个壁之间，这两个壁最初具有不同的温度。使其中一个壁绝热后，系统恢复到平衡状态。我们注意到两种不同的热传输模式及相关的时间尺度：一种与传播的热前沿有关，另一种与内能扩散有关。在以声速移动的热前沿处，压力、温度和密度会突然变化，在其后方留下较低的值。这不同于冲击波、声波或热波。热前沿在壁之间多次移动，并且在被扩散超过之前是主要的热传输模式。我们发现，它在塑造内能流出的动力学过程中可以构成一个量级为1的因子。我们发现冷却这样一个系统比加热更快，而且较热的物体比较冷的物体冷却得更快。后者被称为姆潘巴效应。
