Discrete element simulations for granular material flows: effective thermal conductivity and self-diffusivity

✍ Scribed by M.L. Hunt

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 934 KB
• Volume: 40
• Category: Article
• ISSN: 0017-9310
• DOI: 10.1016/s0017-9310(96)00350-x

✦ Synopsis

This study uses a two-dimensional discrete-element simulation to determine the effective thermal conductivity and self-diffusivity-uantities that depend on the random motions of particles within a granular material flow. The simulations are performed for solid fractions from 0.015 to 0.68 and for different Biot-Fourier numbers. The assumptions used in the simulations are consistent with dense-gas kinetic theory ; hence, the simulation results are shown to compare well with the self-diffusivity based on kinetic theory predictions.

For the heat transfer problem, the analysis differs from classic kinetic theory since the particles can exchange heat with the surrounding fluid. For Biot-Fourier numbers much less than 1. the effective conductivity from the simulations coincides with kinetic theory predictions.

As the Biot-Fourier number increases above 0.1, the results deviate considerably from the classic analysis, but can be predicted using a modified kinetic theory approach.

The simulation is a powerful technique, which can be extended to problems that are not consistent with kinetic theory assumptions.