An efficient numerical model for investigating the effects of anisotropy on the effective thermal conductivity of alumina/Al composites

• A new C++ code is implemented for generating and analyzing granular materials.
• We set up a numerical method based on the DEM for generating alumina/Al materials.
• A statistical analysis is performed for ensuring the randomness of granular packings.
• Thermal conductivities are estimated using FFT-based scheme of Eyre and Milton.
• Effects of anisotropy are investigated and related to the thermal conductivity.

The paper describes an efficient numerical model for better understanding the influence of the microstructure on the thermal conductivity of heterogeneous media. This is the extension of an approach recently proposed for simulating and evaluating effective thermal conductivities of alumina/Al composites. A C++ code called MultiCAMG, taking into account all steps of the proposed approach, has been implemented in order to satisfy requirements of efficiency, optimization and code unification. Thus, on the one hand, numerical tools such as the efficient Eyre–Milton scheme for computing the thermal response of composites have been implemented for reducing the calculation cost. On the other hand, statistical parameters such as the covariance and the distribution of contact angles between particles are now estimated for better analyzing the microstructure. In the present work we focus our investigations on the effects of anisotropy on the effective thermal conductivity of alumina/Al composites. First of all, an isotropic benchmark is set up for comparison purposes. Secondly, anisotropic configurations are studied in order to direct the heat flux. A transversally isotropic structure, taking benefit of wall effects, is finally proposed for controlling the orientation of contact angles. Its thermal capabilities are related to the current issue of heat dissipation in automotive engine blocks.