Abstract
In this chapter, we summarize this book and look to the future. In particular, we raise several key scientific questions for future directions of theoretical thermotics and potential applications in heat regulation.
You have full access to this open access chapter, Download chapter PDF
Keywords
1 Summary
In this book, we present twenty theories of theoretical thermotics, divided into two parts, i.e., inside and outside metamaterials. The major difference is the characteristic length. There is an explicit characteristic length in heat transfer for those fourteen theories inside metamaterials, (much) larger than the structural unit size. The other six theories are beyond the scope of characteristic lengths (outside metamaterials). Therefore, theoretical thermotics can guide the design of both metamaterial-based and metamaterial-free phenomena and functions. Theoretical thermotics is not limited to theories, and we also present simulations and experiments for mutual confirmation. Practical applications, such as invisibility, camouflage, nonreciprocity, and bistability, are also demonstrated. These results may provide insights into novel and advanced thermal regulation.
2 Outlook
Although theoretical thermotics has made significant progress during the last decade, many key scientific problems remain explored. For example, nonreciprocal heat transfer is a recent focus. On the one hand, spatiotemporal modulation becomes an intriguing mechanism for achieving diffusive nonreciprocity [1,2,3,4] due to the advectionlike effect. On the other hand, an isolated thermal system with mass conservation prohibits the advectionlike effect [5]. Therefore, it becomes particularly elusive whether spatiotemporal modulation can yield nonreciprocity in heat transfer. The answer may lie in transient heat transfer due to the novel mechanism of Willis coupling [6]. Therefore, it is promising to reveal more asymmetric diffusion mechanisms in transient heat transfer, especially based on wavelike temperature fields. Moreover, topological heat transfer is another research focus. Many pioneering works related to thermal geometric phases [7], thermal Su-Schrieffer-Heeger models [8,9,10,11], thermal edge states [12], thermal skin effects [13, 14], and thermal topological transitions [15,16,17] have been proposed. However, compared with topological wave propagation [18, 19], the related research in heat transfer is just getting started, and much profound physics remains studied, such as high-order thermal topology.
Theoretical thermotics mainly includes fundamental theories, but we should develop more practical applications. In particular, heat regulation is a critical issue in daily life and industrial production. Hence, theoretical thermotics also needs to focus on practical problems and provide guidance for heat regulation. For example, with the miniaturization of chips, heat dissipation becomes increasingly significant for device protection. Moreover, cooling with energy savings is also a crucial problem, and passive radiative cooling has become a powerful tool [20,21,22]. Therefore, theoretical thermotics should also play a role in solving these urgent requirements.
Last but not least, though theoretical thermotics aims to solve thermal problems, its influence should exceed thermotics. Since heat transfer is a branch of diffusion systems, the research paradigms of theoretical thermotics can also be extended to other diffusive systems, such as particle and plasma diffusions, thereby enriching the means of diffusion regulation. Furthermore, could theoretical thermotics inspire the research in wave systems? This question is very challenging but also very rewarding. In fact, a considerable part of the existing content of theoretical thermotics is inspired by the related research in wave systems, such as from transformation optics [23, 24] to transformation thermotics [25, 26] and from photonic crystals to thermal crystals [27]. It is worth pondering how to make theoretical thermotics more enlightening and impact non-thermal fields. For example, the pioneering attempt to control multiphysical fields originates from theoretical thermotics (thermal plus DC fields [28]), which has been extended to wave control, such as electromagnetic, acoustic, plus water waves [29] and magnetic plus acoustic fields [30, 31]. More research could be expected to extend the paradigms of theoretical thermotics to other non-thermal fields.
Undoubtedly, the future of theoretical thermotics is promising, whether in terms of fundamental research, practical applications, or potential impacts.
References
Torrent, D., Poncelet, O., Batsale, J.C.: Nonreciprocal thermal material by spatiotemporal modulation. Phys. Rev. Lett. 120, 125501 (2018)
Camacho, M., Edwards, B., Engheta, N.: Achieving asymmetry and trapping in diffusion with spatiotemporal metamaterials. Nat. Commun. 11, 3733 (2020)
Xu, L.J., Huang, J.P., Ouyang, X.P.: Tunable thermal wave nonreciprocity by spatiotemporal modulation. Phys. Rev. E 103, 032128 (2021)
Ordonez-Miranda, J., Guo, Y.Y., Alvarado-Gil, J.J., Volz, S., Nomura, M.: Thermal-wave diode. Phys. Rev. Appl. 16, L041002 (2021)
Li, J.X., Li, Y., Cao, P.-C., Qi, M.H., Zheng, X., Peng, Y.-G., Li, B.W., Zhu, X.-F., AlĂą, A., Chen, H.S., Qiu, C.-W.: Reciprocity of thermal diffusion in time-modulated systems. Nat. Commun. 13, 167 (2022)
Xu, L.J., Xu, G.Q., Huang, J.P., Qiu, C.-W.: Diffusive Fizeau drag in spatiotemporal thermal metamaterials. Phys. Rev. Lett. 128, 145901 (2022)
Xu, L.J., Wang, J., Dai, G.L., Yang, S., Yang, F., Wang, G., Huang, J.P.: Geometric phase, effective conductivity enhancement, and invisibility cloak in thermal convection-conduction. Int. J. Heat Mass Transf. 165, 120659 (2021)
Yoshida, T., Hatsugai, Y.: Bulk-edge correspondence of classical diffusion phenomena. Sci. Rep. 11, 888 (2021)
Makino, S., Fukui, T., Yoshida, T., Hatsugai, Y.: Edge states of a diffusion equation in one dimension: rapid heat conduction to the heat bath. Phys. Rev. E 105, 024137 (2022)
Qi, M.H., Wang, D., Cao, P.-C., Zhu, X.-F., Qiu, C.-W., Chen, H.S., Li, Y.: Localized heat diffusion in topological thermal materials (2021). arXiv: 2107.05231
Hu, H., Han, S., Yang, Y.H., Liu, D.J., Xue, H.R., Liu, G.-G., Cheng, Z.Y., Wang, Q.J., Zhang, S., Zhang, B.L., Luo, Y.: Observation of topological edge states in thermal diffusion (2021). arXiv: 2107.05811v1
Xu, L.J., Huang, J.P.: Robust one-way edge state in convection-diffusion systems. EPL 134, 60001 (2021)
Cao, P.-C., Li, Y., Peng, Y.-G., Qi, M.H., Huang, W.-X., Li, P.-Q., Zhu, X.-F.: Diffusive skin effect and topological heat funneling. Commun. Phys. 4, 230–237 (2021)
Cao, P.-C., Peng, Y.-G., Li, Y., Zhu, X.-F.: Phase-locking diffusive skin effect. Chin. Phys. Lett. 39, 057801 (2022)
Xu, G.Q., Li, Y., Li, W., Fan, S.H., Qiu, C.-W.: Configurable phase transitions in a topological thermal material. Phys. Rev. Lett. 127, 105901 (2021)
Xu, G.Q., Yang, Y.H., Zhou, X., Chen, H.S., AlĂą, A., Qiu, C.-W.: Diffusive topological transport in spatiotemporal thermal lattices. Nat. Phys. 18, 450 (2022)
Xu, G.Q., Li, W., Zhou, X., Li, H.G., Li, Y., Fan, S.H., Zhang, S., Christodoulides, D.N., Qiu, C.-W.: Observation of Weyl exceptional rings in thermal diffusion. Proc. Natl. Acad. Sci. U. S. A. 119, e2110018119 (2022)
Ozawa, T., Price, H.M., Amo, A., Goldman, N., Hafezi, M., Lu, L., Rechtsman, M.C., Schuster, D., Simon, J., Zilberberg, O., Carusotto, I.: Topological photonics. Rev. Mod. Phys. 91, 015006 (2019)
Ma, G.C., Xiao, M., Chan, C.T.: Topological phases in acoustic and mechanical systems. Nat. Rev. Phys. 1, 281 (2019)
Yin, X.B., Yang, R.G., Tan, G., Fan, S.H.: Terrestrial radiative cooling: using the cold universe as a renewable and sustainable energy source. Science 370, 786 (2020)
Raman, A.P., Anoma, M.A., Zhu, L.X., Rephaeli, E., Fan, S.H.: Passive radiative cooling below ambient air temperature under direct sunlight. Nature 515, 540 (2014)
Zhai, Y., Ma, Y.G., David, S.N., Zhao, D.L., Lou, R.N., Tan, G., Yang, R.G., Yin, X.B.: Scalable-manufactured randomized glass-polymer hybrid metamaterial for daytime radiative cooling. Science 355, 1062 (2017)
Leonhardt, U.: Optical conformal mapping. Science 312, 1777 (2006)
Pendry, J.B., Schurig, D., Smith, D.R.: Controlling electromagnetic fields. Science 312, 1780 (2006)
Fan, C.Z., Gao, Y., Huang, J.P.: Shaped graded materials with an apparent negative thermal conductivity. Appl. Phys. Lett. 92, 251907 (2008)
Chen, T.Y., Weng, C.-N., Chen, J.-S.: Cloak for curvilinearly anisotropic media in conduction. Appl. Phys. Lett. 93, 114103 (2008)
Maldovan, M.: Narrow low-frequency spectrum and heat management by thermocrystals. Phys. Rev. Lett. 110, 025902 (2013)
Li, J.Y., Gao, Y., Huang, J.P.: A bifunctional cloak using transformation media. J. Appl. Phys. 108, 074504 (2010)
Yang, Y.H., Wang, H.P., Yu, F.X., Xu, Z.W., Chen, H.S.: A metasurface carpet cloak for electromagnetic, acoustic and water waves. Sci. Rep. 6, 20219 (2016)
Zhou, Y., Chen, J., Liu, L., Fan, Z., Ma, Y.G.: Magnetic Cacoustic biphysical invisible coats for underwater objects. NPG Asia Mater. 12, 27 (2020)
Zhan, J.J., Mei, Y.J., Li, K., Zhou, Y., Chen, J., Ma, Y.G.: Conformal metamaterial coats for underwater magnetic-acoustic bi-invisibility. Appl. Phys. Lett. 120, 094104 (2022)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Open Access This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.
The images or other third party material in this chapter are included in the chapter's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the chapter's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
Copyright information
© 2023 The Author(s)
About this chapter
Cite this chapter
Xu, LJ., Huang, JP. (2023). Summary and Outlook. In: Transformation Thermotics and Extended Theories. Springer, Singapore. https://doi.org/10.1007/978-981-19-5908-0_23
Download citation
DOI: https://doi.org/10.1007/978-981-19-5908-0_23
Published:
Publisher Name: Springer, Singapore
Print ISBN: 978-981-19-5907-3
Online ISBN: 978-981-19-5908-0
eBook Packages: Physics and AstronomyPhysics and Astronomy (R0)