Fumeron Sébastien, Moraes Fernando, Pereira Erms
Institut Jean Lamour, Université de Lorraine, Boulevard des Aiguillettes, BP 239, 54506, Vandœuvre les Nancy, France.
Departamento de Física, Universidade Federal Rural de Pernambuco, 52171-900, Recife, PE, Brazil.
Eur Phys J E Soft Matter. 2018 Feb 2;41(2):16. doi: 10.1140/epje/i2018-11623-x.
One interesting way to control heat is to use devices designed by transformation thermics, where artificial media are used. However, once manufactured (either repelling or concentrating heat, for example), besides being mono-purpose, such devices are designed according to a specific geometric boundary conditions. Another problem is the temperature dependence of the materials employed, since their properties are sometimes considered temperature-invariant. In this paper, we show that a previously proposed bi-objective heat switcher (Phys. Rev. E 89, 020501(R) (2014)) is in fact robust against temperature and geometric deformations, due to the topological properties of the molecular nematic orientation. Using a geometrical approach for heat propagation, by performing finite element simulations, we show that a device made by concentric cylinders with thermotropic nematic liquid crystal between them, sustains its functionality even with their molecular thermal conductivities depending on the temperature, achieving a 60% increase and a 44% decrease in the heat flux for each mode. Utilizing topological arguments we show that deformations on the surface of the outer cylinder do not break the operating mode (repeller or concentrator). We present a comparison between our geometrical approach and the transformation thermodynamics to give an additional explanation for the obtained results. We hope the presented device is useful for heat control under mechanical and thermal influence of the external environment.
一种有趣的控制热量的方法是使用由变换热学设计的装置，其中会使用人工介质。然而，一旦制造出来（例如排斥或集中热量），这类装置除了功能单一外，还根据特定的几何边界条件进行设计。另一个问题是所使用材料的温度依赖性，因为它们的特性有时被认为是与温度无关的。在本文中，我们表明，由于分子向列取向的拓扑特性，先前提出的双目标热开关（《物理评论E》89, 020501(R) (2014)）实际上对温度和几何变形具有鲁棒性。通过使用几何方法进行热传播，并进行有限元模拟，我们表明由同心圆柱体制成且中间夹有热致液晶的装置，即使其分子热导率取决于温度，仍能保持其功能，在每种模式下热通量分别实现了60%的增加和44%的降低。利用拓扑论证，我们表明外圆柱表面的变形不会破坏工作模式（排斥器或集中器）。我们对我们的几何方法和变换热力学进行了比较，以便对所得结果给出额外的解释。我们希望所展示的装置在外部环境的机械和热影响下对热量控制有用。
