Achieving thermal magnification by using effective thermal conductivity

A thermal magnification device is proposed by using effective thermal conductivity. Different from transformation optics method, the magnification design is realized analytically by enforcing equality of effective thermal conductivity on the magnification device and the reference case in specified domains. The validity of theoretical analysis is checked by numerical simulation results, which demonstrates the magnifying effects of the proposed design. The device only needs isotropic and homogeneous materials that are easy to obtain in nature. It is also shown that the obtained magnifying conditions are the same as those derived by separation of variables. But the proposed method proves more flexible for multilayered materials and simpler for non-spherical objects under non-uniform thermal fields. It can also be extended to other fields and applications governed by Laplace equation.