Executive Summary We summarise the findings of our second three-year project on the long-term sta- bility of colloidal gels. In our first three-year project, we showed that it was processes occurring at the top of gels that appeared to control the way these mate- rials collapsed under gravity, and that simulations without hydrodynamic interac- tions could not reproduce any of the plethora of observed phenomenology. These findings form the starting points of our second three-year project. First, we use lattice-Boltzmann simulations that take into account hydrodynamic interactions to study a...