{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"f231cd01c63c840772b506775887533bdfd93b2e9e209af1395d57bb82b2faae","created":"2026-10-03T07:18:04Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"6ea34295fcf6e601952e8be07c58035a1b89dd14b656acd9aff7c54418acc26f","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"fluid.strat-rot.mixing-efficiency","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"When turbulence stirs water layered by temperature or salt, part of its energy lifts heavy fluid and mixes the layers and the rest turns into heat. Ocean models assume that a fixed fraction (about one sixth) goes into mixing, but measurements scatter widely.","posed_since":"1980","precise":"Define the flux coefficient $\\Gamma = B/\\epsilon$ ($B$ buoyancy flux, $\\epsilon$ kinetic-energy dissipation rate), set to 0.2 in ocean parameterizations (Osborn 1980). Determine $\\Gamma$ as a function of buoyancy Reynolds number $\\mathrm{Re}_b = \\epsilon/(\\nu N^2)$ ($N$ buoyancy frequency), gradient Richardson number Ri and Prandtl number Pr for stationary stratified shear turbulence, including whether $\\Gamma$ tends to a constant as $\\mathrm{Re}_b \\to \\infty$ at fixed Ri.","problem_ref":null,"references":"","settled_by":"DNS and laboratory experiments at $\\mathrm{Re}_{b} > 10^{3}$ with $\\mathrm{Pr} \\sim 7$ and $\\text{Schmidt number} \\sim 700$ (heat and salt) mapping $\\Gamma(\\mathrm{Re}_{b}, \\mathrm{Ri})$.","status_note":"Laboratory, DNS and ocean estimates range from below 0.1 to above 0.3 depending on forcing, $\\mathrm{Re}_{b}$ and Pr.","title":"Is the flux coefficient of stratified turbulence a universal constant?","topic_ref":"10bf729b197d5ee7bbcb1c2f468901326f7231ccc5c3ae2967db2e962f472a39"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"064771436b6e4f50b976dede8aafafa7ee8ca54677fc6a0bcb8bb396bab2e1d4","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"0fbbb6fa8b65ed1d2b96f6bfa7b919e63203276c9e5eccbf956d2c94796008de","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"TsMQfbcUxucdt3P64YS8tbD-MlmgLz4a82f4YKpNeDO7IGglqC26C5AOAk9SyPjnITTNXTdicNw0nSlvfzmBAA"},"schema":"pubphys.envelope/1"},"record_hash":"064771436b6e4f50b976dede8aafafa7ee8ca54677fc6a0bcb8bb396bab2e1d4","leaf_index":1442}