12 September 2014 Experimental verification of heat flux bending in multilayered thermal metamaterials
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We demonstrate heat flux bending in a multilayered composite considering an effective thermal medium approximation. We show that when the orientation of the composite is physically rotated with respect to the applied temperature gradient , that the resultant thermal conductivity tensor can be modified to be anisotropic, with non-zero off- diagonal elements. The resultant anisotropy was found to be dependent on the angle of rotation as well as the ratio of the thermal conductivities of the constituent materials. We experimentally demonstrate the bending of the heat flux in three such multilayered composites made by alternately stacking 2mm layers of copper ~ 391 W/mK and alloy steel ~ 42 W/mK respectively with three different rotation angles. We show that the resultant heat flux vectors in the composites are oriented at an angle with the applied temperature gradient , due to anisotropy in the thermal conductivity. Our experiments and analysis indicate that heat flux does not have to be collinear with the applied temperature gradient, e.g. the temperature gradient in a particular direction can drive heat flux in an orthogonal direction. Our studies have implications in thermal energy management with possible utility in portable electronics, nano-combustible systems, solar energy utilization etc.
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Krishna P. Vemuri, Krishna P. Vemuri, Fatih M. Canbazoglu, Fatih M. Canbazoglu, Prabhakar R. Bandaru, Prabhakar R. Bandaru, "Experimental verification of heat flux bending in multilayered thermal metamaterials", Proc. SPIE 9160, Metamaterials: Fundamentals and Applications 2014, 916010 (12 September 2014); doi: 10.1117/12.2062157; https://doi.org/10.1117/12.2062157

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