(400p) Drag Model Evaluation through Fluidized Beds and Free-Falling Particles

Authors: 
Buettner, K. E., University of Florida
Kalman, H., Ben-Gurion University of the Negev
Curtis, J. S., UC Davis
Portnikov, D., Ben-Gurion University of the Negev
Drag models are evaluated for two different conditions: particles in a bed and accelerating particles. Some monodisperse drag models scale a drag coefficient by the voidage to predict the drag in a bed. For beds of non-spherical particles, the current models use a non-spherical drag coefficient with a spherical voidage scaling. Results from fluidized bed experiments with cylindrical particles are used to compare with the current non-spherical models. The experiments found that particle elongation can cause significant changes in behavior of the bed. Therefore, two-fluid simulations are performed with the current drag models to compare the flow behaviors. The models for the drag coefficient play a significant role in the accuracy of these predictions. One common agreement is that particle acceleration can impact the drag coefficient, but it is typically ignored in the models. Thus, simple free-falling particle experiments are performed with high-speed cameras to quantify the effect of particle acceleration.