Transformation Multithermotics: Controlling Radiation and Conduction Simultaneously

Any object with nonzero temperature emits thermal radiation described by the Stefan-Boltzmann law, and hence, thermal conduction is always accompanied by thermal radiation. Although a transformation theory has been proposed to control thermal conduction, a transformation theory has not yet been put forward to manipulate thermal radiation, let alone the thermal coupling between radiation and conduction (herein called multithermotics). To solve the problem, we establish the theory of transformation multithermotics to control radiation and conduction simultaneously. As model applications, we also design three devices with functions of cloaking, concentrating, and rotating. These devices are confirmed by transient finite-element simulations. As experimental suggestions, we further design transformation media with two homogeneous and isotropic materials to simplify fabrication. Our results provide general hints to multithermal management, and have potential applications in infrared camouflaging, solar-energy utilizing, etc.