78th Annual Meeting of the APS Division of Fluid Dynamics (Nov 23 — 25, 2025)

V026: Transient Segregation Dynamics of Bidisperse Particle-Laden Flow on an Incline

Authors
  • Yolanda Ba, Harvey Mudd College
  • Yifan Gu , University of California, Los Angeles
  • Lingyun Ding , University of California, Los Angeles
  • Tao Liu , University of California, Los Angeles
  • Qitong Luan , University of California, Los Angeles
  • Andrea L. Bertozzi , University of California, Los Angeles

We experimentally investigate the transient dynamics of bidisperse, negatively buoyant particle-laden flow on an incline. A mixture of two glass particle species, identical in density but differing in size, is suspended in silicone oil and released from a reservoir to flow downslope. The flow exhibits a distinctive transient behavior: initially, the leading front is enriched with smaller particles, but over time, the larger particles overtake and dominate the front. Side-view observations show that the flow begins with nearly well-mixed vertical concentration profiles. At short times, in some cases, the larger particles settle near the bottom, while in others the mixture remains relatively well mixed. As the flow evolves, however, the larger particles consistently rise to the top. We systematically examine how particle volume fraction and size influence these dynamics. As the volume fraction increases from 20% to 35%, the small-particle-dominated front persists for a shorter duration and eventually disappears. Furthermore, when the small-particle diameter decreases from 300-400 micrometers to 100-130 micrometers, the system remains longer in the transient regime, and the larger particles rise more slowly to the top.

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