External pressure dependence of granular orifice flow: Transition to Beverloo flow

In this paper, we have designed and employed a suspended-wall silo to remove Janssen effect in order explore directly the local pressure dependence of Granular Orifice Flow (GOF) systematically. We find that as is removed, flow rate Q changes linearly with external pressure. The slope {\alpha} linear change decays exponentially ratio size orifice {\Phi}/D, which suggests existence characteristic {\lambda} (~2.4). When {\Phi}/D > {\lambda}, gradually zero, on GOF becomes negligible, where Beverloo law retrieves. Our results show not determining factor constant GOF, although it may contribute shield top load. key parameter {\Phi}/D. small can be adjusted by via our setup, useful transportation granules microgravity environment gravity-driven disabled.