Granular discharge through a single orifice is classically described by the Beverloo law, but this localized geometry becomes prone to clogging when the aperture size $D$ is only a few grain diameters $d$. Here, we study dry avalanches of monodisperse glass beads over an inclined perforated mesh as a minimal system for distributed granular filtration. By measuring the mass passing through the mesh as a function of the downslope position, we show that the deposited mass profiles are independent of the initial released mass and are described by a spatial leakage law characterized by the filtration length $\ell$. This length increases with the size ratio $\chi =d/D$, indicating that grain avalanches travel longer distances before being filtered as they approach the aperture width. In contrast to localized silolike discharge, which is suppressed beyond an aperture-size threshold, the inclined mesh remains operational over the explored range by providing a sequence of distributed passage opportunities. A comparison with localized discharge and a first-passage model identify the aperture-scale passage probability as the quantity controlling the macroscopic filtration length. These results connect Beverloo-type discharge, first-order sieving kinetics, and spatially distributed granular filtration.

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• Granular avalanches
• Granular materials