Numerical investigation of shock wave interactions with flexible fiber granular curtains
Phys. Rev. Fluids 11, 084302 – Published 28 August, 2026
DOI: https://doi.org/10.1103/tnfx-8cqz
Abstract
The interaction between air shock waves and granular materials is fundamental in both natural phenomena and engineering applications. However, the role of particle morphology, particularly that of flexible fibers, remains unclear. Here we numerically investigate shock-induced dispersal and resistance in dense flexible fiber curtains, using a coupled Discrete Element Method and Computational Fluid Dynamics (DEM-CFD) framework. We find that the dispersal dynamics and shock attenuation are controlled by the competition between fiber interlocking and the internal solid volume fraction of clusters. Low aspect ratio fiber systems, which have high cluster volume fractions, exhibit nonuniform expansion, with instabilities at the downstream interface leading to pronounced granular ejections, resulting in rapid dispersion of the clusters. In contrast, high aspect ratio fiber systems, which possess lower cluster volume fractions, maintain integrity of the clusters for much longer periods due to the fiber interlocking contacts, thereby suppressing the interfacial instabilities. Consequently, stronger resistance to the shock by the fiber cluster is obtained at early stage of the wave propagation for the low aspect ratio fibers, and the stronger shock resistance occurs at a later stage for the high aspect ratio fibers. Fiber flexibility modulates these behaviors by promoting fiber bending deformation, effectively weakening geometric interlocking and reducing air drag. To describe the time evolution of the fiber curtain expansion, the fiber aspect ratio should be included in the scaling law to account for the effect of fiber shape on the air drag. For the very flexible fibers, an effective fiber aspect ratio is required to replace the nominal fiber aspect ratio in the scaling law, in order to take the effect of large fiber deformation into account. These findings offer a fundamental understanding of the shock-driven multiphase flows and dispersal of the elongated, flexible fibers.
