On the evaluation of non-Fourier effects in heat pulse experiments

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 has been observed that the thermal behavior of heterogeneous materials can show deviation from the classical Fourier equation, resulting in a different thermal diffusivity and requiring further thermal parameters to identify. Such heterogeneity can be inclusions in metal foams, layered structure in composites, or even cracks and porous parts in rocks. Furthermore, the next candidate, the Guyer-Krumhansl equation is tested on these experiments with success. However, these recent evaluations required a computationally intensive fitting procedure using countless numerical solutions, even when a good initial guess for the parameters is found by hand. This paper presents a Galerkin-type discretization for the Guyer-Krumhansl equation, which helped us find a reasonably simple analytical solution for time-dependent boundary conditions. Utilizing this analytical solution, we developed a new evaluation technique to immediately estimate all the necessary thermal parameters using the measured temperature history.

Automated summary

The heat pulse experiment is a well-known method for measuring thermal diffusivity, but the thermal behavior of heterogeneous materials may deviate from the classical Fourier equation, requiring additional thermal parameters. The Guyer-Krumhansl equation has been successfully tested on such materials, but the evaluations often involve computationally intensive fitting procedures. A new evaluation technique has been developed to estimate all necessary thermal parameters using measured temperature history.