Steady granular discharge across aperture shapes
Abstract
We recently proposed a framework for the steady mass flux of particles through circular apertures [R.~S.~Sharma \textit{et al.}, Phys. Rev. Lett. \textbf{136}, 068204 (2026)]. Here, we combine experiments and discrete-element simulations of spherical particles discharging through triangular and rectangular apertures to test this framework beyond circular openings. Despite changes in aperture shape, we observe a similar free-fall flux, with a modified relevant transport length. Deviations due to confinement reflect packing modifications, which are explained by geometry. A boundary layer dilation imposed by the aperture edge is shown to be a mechanism for the decrease of flux across various aperture shapes. By integrating the local packing deficit over the opening, we identify a hydraulic diameter Dh=4A/P, where A and P are the aperture area and perimeter, respectively, as the leading confinement length. This length also provides a reference scale, √(gDh), for the mean outlet velocity when the aperture is much larger than an individual particle. The same local packing model predicts the field in a lens-shaped aperture without further fitting, while the normalized discharge rates follow a common trend across the tested shapes.
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BibTeX
@misc{zhao2026steady,
title = {{Steady granular discharge across aperture shapes}},
author = {Kevin Yifan Zhao and Ram Sudhir Sharma and Alexandre Leonelli and Eckart Meiburg and Alban Sauret},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.02543},
eprint = {2610.02543},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.02543},
}
RIS
TY - UNPB
TI - Steady granular discharge across aperture shapes
AU - Kevin Yifan Zhao
AU - Ram Sudhir Sharma
AU - Alexandre Leonelli
AU - Eckart Meiburg
AU - Alban Sauret
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.02543
UR - https://arxiv.org/abs/2610.02543
AB - We recently proposed a framework for the steady mass flux of particles through circular apertures [R.~S.~Sharma \textit{et al.}, Phys. Rev. Lett. \textbf{136}, 068204 (2026)]. Here, we combine experiments and discrete-element simulations of spherical particles discharging through triangular and rectangular apertures to test this framework beyond circular openings. Despite changes in aperture shape, we observe a similar free-fall flux, with a modified relevant transport length. Deviations due to confinement reflect packing modifications, which are explained by geometry. A boundary layer dilation imposed by the aperture edge is shown to be a mechanism for the decrease of flux across various aperture shapes. By integrating the local packing deficit over the opening, we identify a hydraulic diameter D_h=4A/P, where A and P are the aperture area and perimeter, respectively, as the leading confinement length. This length also provides a reference scale, √(gD_h), for the mean outlet velocity when the aperture is much larger than an individual particle. The same local packing model predicts the field in a lens-shaped aperture without further fitting, while the normalized discharge rates follow a common trend across the tested shapes.
ER -