热超构材料的研究进展

Research progress in thermal metamaterials

由于光波、声波、地震波和水波都遵循波动方程,所以,2006年光学隐身衣(optical cloak)原理在Science杂志上发表后,光学隐身衣的设想很快就从最初的光波推广到了声波、地震波和水波,至今方兴未艾。由于热传导满足的是扩散方程,并且波动方程与扩散方程在物理机制上迥异,这就使得把光学隐身衣推广到热学隐身衣的尝试不得不面临来自原理上的挑战,可能也正因为如此,国际上对热超构材料的研究非常缓慢:早在2008年,就有学者在光学隐身衣的启发下,通过有限元模拟,揭示了热学隐身衣和热流反转等反常热功能或热现象,从而提出热超构材料(thermal metamaterial)的概念,但是,直到2012年,这个概念才被实验验证。由于其中蕴含着巨大的潜在应用价值,该实验工作发表后,热超构材料开始得到国际同行的广泛关注。文章的主要目的就是向读者介绍这一类新型功能材料——热超构材料的物理原理、发展历程及其理论和实验研究进展。

The principle of optical cloaking, first published in Science in 2006, has been quickly extended from light waves to acoustic, seismic, and water waves, as they all obey the wave equations. Because thermal conduction satisfies diffusion equations as well as wave equations, and the former have different physical mechanisms, the extension from optical cloaking to thermal cloak- ing is a greater challenge. Thus, research on thermal metamaterials has been very slow. As early as in 2008, various counter-intuitive functions and properties like thermal cloaks and thermal inverters were proposed on the basis of finite element simulations, and the concept of thermal metamaterials was introduced. However, this concept was only demonstrated experimentally in 2012. On account of their potential applications, thermal metameterials soon received much attention from the internation- al community. The main aim of this review is to describe this new type of functional material- thermal metamaterials. We shall present an overview of their physical principles, history, and prog- ress in both theoreical and experimental research.