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Open AccessArticle

Emergence of Non-Fourier Hierarchies

Department of Energy Engineering, Faculty of Mechanical Engineering, BME, 1521 Budapest, Hungary
Montavid Thermodynamic Research Group, 1112 Budapest, Hungary
Department of Theoretical Physics, Institute for Particle and Nuclear Physics, Wigner Research Centre for Physics, 1525 Budapest, Hungary
Author to whom correspondence should be addressed.
Entropy 2018, 20(11), 832;
Received: 21 August 2018 / Revised: 17 October 2018 / Accepted: 26 October 2018 / Published: 30 October 2018
The non-Fourier heat conduction phenomenon on room temperature is analyzed from various aspects. The first one shows its experimental side, in what form it occurs, and how we treated it. It is demonstrated that the Guyer-Krumhansl equation can be the next appropriate extension of Fourier’s law for room-temperature phenomena in modeling of heterogeneous materials. The second approach provides an interpretation of generalized heat conduction equations using a simple thermo-mechanical background. Here, Fourier heat conduction is coupled to elasticity via thermal expansion, resulting in a particular generalized heat equation for the temperature field. Both aforementioned approaches show the size dependency of non-Fourier heat conduction. Finally, a third approach is presented, called pseudo-temperature modeling. It is shown that non-Fourier temperature history can be produced by mixing different solutions of Fourier’s law. That kind of explanation indicates the interpretation of underlying heat conduction mechanics behind non-Fourier phenomena. View Full-Text
Keywords: non-Fourier heat conduction; thermal expansion; heat pulse experiments; pseudo-temperature; Guyer-Krumhansl equation non-Fourier heat conduction; thermal expansion; heat pulse experiments; pseudo-temperature; Guyer-Krumhansl equation
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Fülöp, T.; Kovács, R.; Lovas, Á.; Rieth, Á.; Fodor, T.; Szücs, M.; Ván, P.; Gróf, G. Emergence of Non-Fourier Hierarchies. Entropy 2018, 20, 832.

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