The granular column collapse: A retrospective

The granular column collapse consists on the release of a granular volume let to deform or collapse under self-weight until eventually reaching a temporary or permanent stable deposit. Similar to a dam-break in fluid mechanics or a slump test in civil engineering, this configuration was first utilized by the granular media community in 2004. Since then, the granular column collapse has become a benchmark configuration for studying the mobility of granular flows, thanks to its easy setup and reproducibility, and captured rapidly the attention of a wider range of scientific fields working with granular materials. This review covers more than two decades, and even more, of studies employing the granular column collapse as means to understand or describe the motion of grains and their interaction with ambient fluids or gases. This review covers the wide range of fields where the column collapse has been used and includes a database with the collection of experimental works. The aim is to present the questions already answered and summarize the lessons learned from these experimental models. The wealth of applications where the granular column has been used demonstrates how this simple yet rich configuration is proving valuable for validating existing and future particle-based numerical methods.