{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"e535f167aa001bc57b591ca70b70b8d25a2d2fe72dcf451d5d251b091d461606","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["631f0d788c551ec92a90adef66622a05178e7670c8518049fc2359ccf42fdbd1","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"6d95b0446a654fecb155c00b6f863daec02abc799f8b24ecded5a8a81f905de7","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":["ai:gpt-5.5"],"external_id":"bio.granular-rheology.silo-clogging","kind":"well-posed","literature_status":"contested","n":"2","parents":[],"plain":"Grains pouring through a small hole in a silo eventually jam by forming an arch. It is disputed whether there is a hole size above which jamming never happens, or whether jamming only becomes extremely rare.","posed_since":"","precise":"For grains of diameter $d$ discharging through an orifice of diameter $D$, the mean number of grains $\\langle s\\rangle$ discharged between clogs grows with $D/d$. Determine whether $\\langle s\\rangle$ diverges at a finite critical $D_c/d$ as $(D_{c} - D)^{-\\gamma}$, or grows exponentially in a power of $D/d$ with no true transition, in 2D and 3D silos.","problem_ref":"631f0d788c551ec92a90adef66622a05178e7670c8518049fc2359ccf42fdbd1","references":"","settled_by":"Measurements or simulations of $\\langle s\\rangle(D/d)$ over enough decades to separate a power-law divergence from exponential growth, supported by a theory of arch formation.","status_note":"Thomas and Durian (2015, https://doi.org/10.1103/PhysRevLett.114.178001) found exponential growth with no critical outlet size, contradicting the earlier power-law divergence of Zuriguel et al. (2005); the issue is unresolved in 3D and for frictional grains (2026).","title":"Is there a critical outlet size for clogging of granular 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