Granular collapse in fluids: Dynamics and flow regime identification

This study is specifically oriented towards falling process of collapsing material under various fluid conditions, employing the computational fluid dynamics-discrete element method (CFD-DEM) to primarily investigate the dynamics and scaling laws of deposit morphology of collapsed material.

Through a comprehensive analysis of particle sedimentation in fluids, we introduce a refined inertial characteristic time for granular collapse within the inertial regime. Subsequently, we propose modifications to conventional fluid-particle density ratio and Reynolds number, aiming to enhance the accuracy of depicting collapse dynamics and identifying flow regimes across diverse column heights and fluid conditions. Finally, we construct a phase diagram of flow regimes using modified dimensionless numbers, emphasizing the role of column height in transition between viscous and inertial regimes.