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Morphological transitions in partially gas-fluidized granular mixtures
Anders Nermoen1, Christophe Raufaste, Simon Daniel deVilliers
1Physics of Geological Processes, University of Oslo, Box 1048 Blindern, N-0316 Oslo, Norway. anderne@fys.uio.no
Pattern formation in granular mixtures is driven by gas flow. Particle segregation and pipe formation occur due to localized fluidization and sedimentation, with implications for geological processes.
Area of Science:
- Fluid dynamics
- Granular physics
- Geological processes
Background:
- Partial fluidization of granular mixtures occurs at gas velocities insufficient to fluidize all particles.
- Bimodal granular mixtures exhibit complex pattern formation over time.
Purpose of the Study:
- To investigate pattern formation during the defluidization of partially fluidized bimodal granular mixtures.
- To understand the role of particle concentrations and gas velocity in pattern evolution.
Main Methods:
- Experimental investigation of defluidization dynamics.
- Analysis of pattern formation based on particle size distribution and gas velocity.
Main Results:
- Vertically oriented pipes of large particles form at the interface between fluidized and static zones.
- Heterogeneities in permeability focus flow, leading to localized fluidization and particle segregation.
- Observed patterns depend on particle concentrations and gas velocity.
Conclusions:
- The interplay of material properties, fluid flow, and deformation drives pattern formation.
- These findings offer insights into geological processes involving granular flow and segregation.
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