An alternative experimental approach and a numerical analysis for the study of destabilization by localized fluidization of an immersed dense granular material are presented. To visualize the evolutions of the internal structure of the granular medium, the hydrogel beads, composed of about 99% of water and having substantially the same refraction indexes, are used as solid phase. A LED lighting system is used in place of a laser lighting system. As a result, the optical access restriction of porous structure is removed. A real economic alternative for the experimental study of fluid-grain coupling during destabilization by localized fluidization of a granular material is created. The experimental phenomenology presented in the literature is verified: the system passes successively through three different stationary regimes: static regime, fluidized cavity regime, and fluidized chimney regime. Some restrictions of using hydrogel beads as particles in the study of liquid-solid interaction are also discussed.

中文翻译：

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局部流化浸没致密颗粒材料的失稳：实验和数值研究

介绍了一种替代的实验方法和数值分析，用于研究浸没的致密颗粒材料的局部流化引起的不稳定。为了使颗粒介质内部结构的演变可视化，由约 99% 的水组成并具有基本相同的折射率的水凝胶珠被用作固相。LED照明系统用于代替激光照明系统。结果，去除了多孔结构的光学访问限制。为通过颗粒材料的局部流化在不稳定过程中进行流-颗粒耦合实验研究，创造了一种真正经济的替代方案。文献中提出的实验现象学得到验证：系统依次通过三种不同的静止状态：静态状态、流化腔状态和流化烟囱状态。还讨论了在液固相互作用研究中使用水凝胶珠作为颗粒的一些限制。