# Behavior of confined granular beds under cyclic thermal loading

## TL;DR

This study uses numerical simulations to analyze how cyclic thermal loading affects confined granular beds, revealing pressure variations, convection cell formation, and the influence of container shape and thermal expansion coefficients.

## Contribution

It introduces a detailed numerical analysis of thermal cycling effects on granular beds, highlighting the impact of container geometry and thermal properties on pressure and flow patterns.

## Key findings

- Small changes in container shape drastically reduce peak pressure.
- Convection cells form inside the granular material during thermal cycles.
- Vorticity scales quadratically with thermal expansion ratio.

## Abstract

We investigate the mechanical behavior of a confined granular packing of irregular polyhedral particles under repeated heating and cooling cycles by means of numerical simulations with the Non-Smooth Contact Dynamics method. Assuming a homogeneous temperature distribution as well as constant temperature rate, we study the effect of the container shape, and coefficients of thermal expansions on the pressure buildup at the confining walls and the density evolution. We observe that small changes in the opening angle of the confinement can lead to a drastic peak pressure reduction. Furthermore, the displacement fields over several thermal cycles are obtained and we discover the formation of convection cells inside the granular material having the shape of a torus. The root mean square of the vorticity is then calculated from the displacement fields and a quadratic dependency on the ratio of thermal expansion coefficients is established.