Solid-liquid rotary kilns: An experimental and CFD-DEM study

Experiments for the validation of unresolved CFD-DEM software for solid-liquid flows are often expensive, time consuming and generally provide little insight into the local particles dynamics. Additionally, several DEM parameters such as the particle surface properties are often obtained from experiments in air and used for all CFD-DEM simulations even when the fluid is a liquid. We design and perform a simple and time efficient gas-solid and liquid-solid rotary kiln benchmark for the purpose of creating a validation case for unresolved CFD-DEM software which we use to validate the unresolved CFD-DEM model of the open-source software Lethe. This case, which contains dense solid-solid contacts and strong solid-fluid forces gives insight on the importance of proper calibration of DEM surface properties in solid-liquid flows as well as on the importance of the lift force. Furthermore, it is highly sensitive to the accuracy of the CFD discretization.

Automated summary

Experiments for validating unresolved CFD-DEM software for solid-liquid flows are costly and time-consuming, and provide limited insights into local particle dynamics. The use of DEM parameters obtained from air experiments for all CFD-DEM simulations, even when dealing with liquids, is common. In this study, we designed and conducted a simple and time-efficient benchmark experiment for gas-solid and liquid-solid rotary kilns to create a validation case for unresolved CFD-DEM software. We used this case to validate the unresolved CFD-DEM model of the open-source software Lethe. The experiment highlights the importance of proper calibration of DEM surface properties and the lift force in solid-liquid flows, and shows that it is highly sensitive to the accuracy of CFD discretization.