Transient freeform thermal metamaterials via inverse-design

Thermal metamaterials have gained significant interest because of their unconventionally tailored properties. Analytical transformation optics and numerical optimization method dealing with structural parameters have motivated unique and beneficial potential applications for thermal management. Nevertheless, analytical design methods are expected to possess complex artificial mathematical derivation. Moreover, a self-driven standard strategy that meets the demands of different design requirements is unavailable. Herein, we report an inverse-design strategy using topology optimization for freeform thermal metamaterials in a transient state. The design of thermal metamaterials in transient state is converted to an inverse heat conduction problem, in which the sensitivity analysis and the adjoint problem are defined over the strong-form. The thermal conductivity and volumetric heat capacity of thermal metadevices are evolved simultaneously relying on the conjugate gradient method. Thermal metadevices with irregular shapes are specifically designed to verify the feasibility and universality of the paradigm. This study constructs a standard programmable design strategy for transient freeform thermal metamaterials and further suggests conducting more explorations in other Laplace fields, such as DC and magnetostatics.