2019/12/07 by A. M. Cervantes-Álvarez, Y.Y. Escobar-Ortega, Cervantes-Alvarez, A. M. +5
Engineering · #Applied Physics (physics.app-ph) #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Heat Transfer #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.1912.03548
openalex publication_date 2019/12/07 · openalex created_date 2019/12/13 · openalex updated_date 2026/07/28
A jet of water entering into a pool of the same liquid can generate air entrainment and form bubbles that rapidly raise to the surface and disintegrate. Here we report the equivalent phenomenon produced by a plunging dry granular jet, so far unexplored. For grains smaller than a critical size, the granular jet entering into the pool produces air entrainment that leads to bubbles formation. The bubbles formed are covered by a shell of grains attached to the bubble air-water interface due to capillary-induced cohesion. In contrast to classical air bubbles, these "granular bubbles" are stable over time because the granular shell prevents coalescence and keeps the air encapsulated either if the bubbles rise to the surface or sink to the bottom of the pool, which is determined by the competition of the buoyant force and the weight of the assembly. Experimentally, we show how the bubble size and volume of entrained air depend on the grain size, liquid properties and jet impact velocity.