Flexible composite foam in vibrating gas-liquid granules


The movement of grains, for example, sand or catalyzed particles, is based on many natural and industrial processes. Grain variability is difficult to understand and model due to the transitions between solid, liquid, and gas-like properties, and previous series of models have difficulty capturing these transitions. Foam-like voids typically cause disturbances in suspended grain streams. We create composition bubbles at a resonant frequency by setting the properties or system size neutral, at a resonant frequency, and we identify the corresponding physics using a compatible cell. We provide continuous communication that allows us to predict the pre-readings with fluid-solid transitions. Continuous modeling and controlled foam design can improve and improve industrial processes.


The variability of grain materials is critical to many natural and industrial processes. Grain movement is often similar to normal flow. Food, medicine, and clean energy systems use systems that allow gas to flow through the grains by blocking particles in a liquid or bubble-like liquid. Here, we show that repetitive vibration of these systems can transform the normal turbulent movement of these bubbles into a dynamic structure, creating a movement that controls the frequency of movement of objects and gas. The echo frequency is independent of particle properties and system size, and a simple acoustic model captures this frequency. Imitation of particle particles shows the formation of bubbles due to rapid, local transitions between solid and liquid-like properties in vibrating grains. For gas-solid flows existing continuous models struggle to capture these fluid-strong transitions and cannot predict the structure of the bubble. We provide a link to strong stress, which predicts fluid-strong transitions and therefore contains experimental structured bubble patterns. The same structure is observed in the fluctuating liquid beds by fluctuating the flow of gas. We show that vibrating, shiny liquid beds can produce a more ordered structure, especially when the system size increases. The flexible structure and continuous model presented here provide the capacity to address the major issues that currently limit the use of floating beds in existing and emerging technologies.


  • Author contributions – QG, TMK, and CMB designed research; QG, YZ, AP, KX, TMK and CMB conducted research. QG, YZ and CMB analyzed data; And QG and CMB wrote the paper.

  • The authors state that there is no competitive interest.

  • This article is a direct submission of PNAS.

  • This article contains online support information at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2108647118/-/DCSupplemental.

Data availability

All research data is included in the text and / or supporting information.

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