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Results of heat pulse experiments in various artificial and natural materials are reported in the paper. The experiments are performed at room temperature with macroscopic samples. It is shown that temperature evolution does not follow the…

Statistical Mechanics · Physics 2018-05-08 P. Ván , A. Berezovski , T. Fülöp , Gy. Gróf , R. Kovács , Á. Lovas , J. Verhás

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…

The heat pulse experiment is a well-known method for determining thermal diffusivity. However, neither the measurement nor the evaluation methodologies are straightforward for heterogeneous, highly porous materials. In the present paper, we…

Classical Physics · Physics 2023-08-21 Anna Fehér , Róbert Kovács , Ákos Sudár , Gergely Gábor Barnaföldi

The existence of non-Fourier heat conduction is known for a long time in small and low temperature systems. The deviation from Fourier's law has been found at room temperature in heterogeneous materials like rocks and metal foams…

Statistical Mechanics · Physics 2018-04-17 Róbert Kovács

The heat pulse (flash) experiment is a well-known and widely accepted method to measure the thermal diffusivity of a material. In recent years, it is observed that the thermal behavior of heterogeneous materials can show deviation from the…

Applied Physics · Physics 2021-01-05 Anna Fehér , Róbert Kovács

It is a long-lasting task to understand heat conduction phenomena beyond Fourier. Besides the low-temperature experiments on extremely pure crystals, it has turned out recently that heterogeneous materials with macro-scale size can also…

There are various situations where the classical Fourier's law for heat conduction is not applicable, such as heat conduction in heterogeneous materials or for modeling low-temperature phenomena. In such cases, heat flux is not directly…

Statistical Mechanics · Physics 2018-05-04 A. Rieth , R. Kovács , T. Fülöp

The variety and complexity of heterogeneous materials in the engineering practice are continuously increasing, open-cell metal foams filled with phase change materials are typical examples. These are also having an impact on the recent…

Applied Physics · Physics 2023-07-03 Robert Kovacs

Phonon heat conduction over length scales comparable to their mean free paths is a topic of considerable interest for basic science and thermal management technologies. Although the failure of Fourier's law beyond the diffusive regime is…

Materials Science · Physics 2019-08-28 Chengyun Hua , Lucas Lindsay , Xiangwen Chen , Austin Minnich

A novel equation of heat conduction is derived with the help of a generalized entropy current and internal variables. The obtained system of constitutive relations is compatible with the momentum series expansion of the kinetic theory. The…

Statistical Mechanics · Physics 2015-04-16 R. Kovács , P. Ván

The experimental basis and theoretical background of non-Fourier heat conduction is shortly reviewed from the point of view of non-equilibrium thermodynamics. The performance of different theories is compared in case of heat pulse…

Statistical Mechanics · Physics 2016-08-04 Peter Ván

It has been observed in many numerical simulations, experiments and from various theoretical treatments that heat transport in one-dimensional systems of interacting particles cannot be described by the phenomenological Fourier's law. The…

Statistical Mechanics · Physics 2019-11-12 Abhishek Dhar , Anupam Kundu , Aritra Kundu

Momentum-conserving one-dimensional models are known to exhibit anomalous Fourier's law, with a thermal conductivity varying as a power law of the system size. Here we measure, by numerical simulations, several cumulants of the heat flux of…

Statistical Mechanics · Physics 2015-05-18 E. Brunet , B. Derrida , A. Gerschenfeld

The Fourier law of heat conduction describes heat diffusion in macroscopic systems. This physical law has been experimentally tested for a large class of physical systems. A natural question is to know whether it can be derived from the…

Analysis of PDEs · Mathematics 2019-12-10 Thierry Bodineau , Isabelle Gallagher , Laure Saint-Raymond

The Guyer-Krumhansl heat equation has numerous important practical applications in both low-temperature and room temperature heat conduction problems. In recent years, it turned out that the Guyer-Krumhansl model can effectively describe…

Analysis of PDEs · Mathematics 2022-07-14 Anderson Ramos , Róbert Kovács , Mirelson Freitas , Almeida Júnior

The onset of Fourier's law in a one-dimensional quantum system is addressed via a simple model of weakly coupled quantum systems in contact with thermal baths at their edges. Using analytical arguments we show that the crossover from the…

Statistical Mechanics · Physics 2015-05-13 Y. Dubi , M. Di Ventra

We give a rigorous derivation of Fourier's law from a system of closure equations for a nonequilibrium stationary state of a Hamiltonian system of coupled oscillators subjected to heat baths on the boundary. The local heat flux is…

Mathematical Physics · Physics 2009-11-11 Jean Bricmont , Antti Kupiainen

The microscopic origins of Fourier's venerable law of thermal transport in quantum electron systems has remained somewhat of a mystery, given that previous derivations were forced to invoke intrinsic scattering rates far exceeding those…

Mesoscale and Nanoscale Physics · Physics 2025-10-09 Sosuke Inui , Charles A. Stafford , Justin P. Bergfield

Among the numerous heat conduction models, the Guyer--Krumhansl equation has a special role. Besides its various application possibilities in nanotechnology, cryotechnology, and even in case of modeling heterogeneous materials, it poses…

Applied Physics · Physics 2024-05-16 Mátyás Szücs , Carmelo Filippo Munafo , Róbert Kovács

We derive Fourier's law for a completely coherent quasi one--dimensional chaotic quantum system coupled locally to two heat baths at different temperatures. We solve the master equation to first order in the temperature difference. We show…

Quantum Physics · Physics 2015-05-20 Thomas H. Seligman , Hans A. Weidenmueller
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