Exploring optimal topology of thermal cloaks by CMA-ES

• Published in: Applied physics letters Vol. 112; no. 6
• Main Authors: Fujii, Garuda, Akimoto, Youhei, Takahashi, Masayuki
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 05.02.2018
• Subjects: Aluminum; Applied physics; Biological evolution; Configuration management; Covariance matrix; Fitness; Heat flux; Mathematical analysis; Metamaterials; Stealth technology; Temperature distribution; Topology optimization; Visibility
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5016090

This paper presents topology optimization for thermal cloaks expressed by level-set functions and explored using the covariance matrix adaptation evolution strategy (CMA-ES). Designed optimal configurations provide superior performances in thermal cloaks for the steady-state thermal conduction and succeed in realizing thermal invisibility, despite the structures being simply composed of iron and aluminum and without inhomogeneities caused by employing metamaterials. To design thermal cloaks, a prescribed objective function is used to evaluate the difference between the temperature field controlled by a thermal cloak and when no thermal insulator is present. The CMA-ES involves searches for optimal sets of level-set functions as design variables that minimize a regularized fitness involving a perimeter constraint. Through topology optimization subject to structural symmetries about four axes, we obtain a concept design of a thermal cloak that functions in an isotropic heat flux.