Investigation of mechanism for a thermal cloak metamaterial by an entropy production approach

With the development of metamaterials, microscale thermal cloak attracted many researchers' attention. It was found that a thermodynamic cloak has unique characteristics of heat transfer transformation, with fundamental principle of transformation optics applied in thermodynamic field. An overview of thermal cloak related studies have not explained the physical mechanism in view of energy aspect. In the current work, two-dimensional heat transfer model of a multilayer thermal cloak was investigated through simulation according to Schittny's microstructured model as well as an only polydimethylsiloxane protected layer model and plate model as control groups. Numerical simulations were developed with ANSYS FLUENT software for three models respectively in the process of heating to analysis the heat transfer and stealth protection during transient heat transfer process. The simulation results were agreed well with other's previous experiment results on temperature distribution. The cloaking mechanism was analyzed by entropy generation approaches, and deriving the thermodynamics explanation at the aspect of the energy transfer. Thermodynamic cloak structure has a good heat stealth effect on the process of heat transfer, without the effecting outside the protected object on the distribution of both temperature and energy. Thermodynamic cloak control the energy dissipation inside the multi-layer structure, but the maximum dissipation position was shifted along the heat transfer processing.