2025/05/30 by Jack Luong, Sarah C. Burnett, Sarah Cassie Burnett +4 · 2 voices
Agricultural and Biological Sciences · Engineering · Physics and Astronomy · #35Q70 #70-10 #76D08 #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Particle Dynamics in Fluid Flows #Soft Condensed Matter (cond-mat.soft) #Soil erosion and sediment transport #cond-mat.soft #physics.flu-dyn
paper · pdf · doi:10.48550/arxiv.2505.24114
openalex publication_date 2025/05/30 · arxiv published 2025/05/30 · arxiv updated 2025/05/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study bidisperse suspensions -- suspensions where there are two particle species of the same density but different sizes -- of a viscous fluid on an incline. We use a lubrication theory/thin film model to form a hyperbolic system of three conservation laws for the height and particle volume fractions. The model predicts, over a range of parameters, that the larger particles rise to the top of the layer, consistent with the well-known `Brazil-nut effect' for granular media. The model predicts well-separated fronts of the two species of particles, behind a clear fluid front, at lower inclination angles and volume fractions. This corresponds to a triple shock structure in the system of conservations. At higher inclination angles and volume fractions the particles congregate at a high concentration at the leading front corresponding to a singular shock in the model. We find excellent agreement between theory and experiments in terms of the overall dynamic structures as the parameters vary.