{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"71cdef5c7f2ba1e45abb15c8e516f433b74fba97ed17de739b4739d8a461274a","created":"2026-10-03T07:18:03Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"5ae389a75dfdc0e93e8a728e36347face7b97ab1de2eb9b621de69f23d0a1bb1","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"fluid.contact-lines.hysteresis-pinning","kind":"phenomenon","literature_status":"contested","n":"1","parents":[],"plain":"A liquid edge creeping over a dirty surface catches on tiny defects and becomes ragged, and the theory of a springy line pinned by randomly placed defects predicts how ragged. Experiments find a rougher edge than the theory, and nobody knows what the theory leaves out.","posed_since":"","precise":"Model the contact line as an elastic line with long-range elasticity (elastic $\\mathrm{energy}\\sim \\mid k\\mid\\,\\mid h_k\\mid^2$ for a deformation $h_k$ of wavenumber $k$) in a random field of defects. Numerical simulations of this model give the roughness exponent at depinning $\\zeta = 0.388 \\pm 0.002$ (first-order renormalization-group estimate $1/3$), while experiments (liquid helium on cesium, water-glycerol mixtures on disordered surfaces) have reported values near 0.5. Identify what the model omits (nonlinear elasticity at large deformation, thermal activation, crossover or finite-size effects, viscous dissipation, or analysis artefacts) and show that the corrected model reproduces the measured $\\zeta$ and depinning exponents.","problem_ref":null,"references":"","settled_by":"An experiment on a surface with designed, characterized disorder that measures $\\zeta$ over a wide range of scales, matched by simulations of the line model with the same disorder and any added nonlinear elasticity or thermal effects.","status_note":"","title":"Why measured contact-line roughness exceeds the elastic-line model prediction","topic_ref":"7a825c5c00d33b62e371e3769546f5338a06f02c5d234ce8602c61be90e57f13"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"8af3c6cbdabff63fcc763d05647f026f0205cc5b33f9ddfc63acdb15207e538d","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"6fb03f959d06bd661c1708b564fc0efff030691aa8ff4c612e427df28867b808","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"94DscP5FuR5HSj8lmJphjq6Zq0vf8ptpiJe6Q5Jpgm06Ru3boHU1aGuP2Fb0ZSsT09FFK0QwfF7WPU32rK8uAw"},"schema":"pubphys.envelope/1"},"record_hash":"8af3c6cbdabff63fcc763d05647f026f0205cc5b33f9ddfc63acdb15207e538d","leaf_index":1403}