{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"c5de49e0e21c84f1fba55ca096ecbb9ea57bc46cdf78b6853f608c82648e5ccc","created":"2026-10-03T07:18:04Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"9f74ca8dfa6641e34f7eb37b16a88e080758f4d5208516416de1bebbd379cfc3","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"fluid.strat-rot.rayleigh-taylor-alpha","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"When heavy fluid rests on light fluid under gravity, the interface overturns and a turbulent mixing zone grows with the square of time. Simulations give a growth rate about half of what experiments measure, and whether a single universal value exists is unknown.","posed_since":"","precise":"For incompressible miscible Rayleigh-Taylor turbulence with Atwood number $A=(\\rho_1-\\rho_2)/(\\rho_1+\\rho_2)$ and acceleration g, the bubble penetration grows as $h_b=\\alpha_b A g t^2$ at late times. Determine whether $\\alpha_b$ reaches a universal limit independent of the initial interface perturbation spectrum as $h_b/\\lambda_0\\to \\infty$ ($\\lambda_0$ the dominant initial wavelength), or retains permanent memory of long-wavelength initial content, and give its value at low $A$.","problem_ref":null,"references":"","settled_by":"Experiments and DNS with measured and matched initial interface spectra followed to large $h_b/\\lambda_0$, showing whether $\\alpha_b$ converges to a common value.","status_note":"The Alpha-Group comparison found simulated $\\alpha_b \\sim 0.025 \\pm 0.003$ against experimental $0.057 \\pm 0.008$ and attributed the gap partly to long-wavelength initial perturbations (Dimonte et al., Physics of Fluids 2004).","title":"Is the Rayleigh-Taylor mixing growth constant universal?","topic_ref":"10bf729b197d5ee7bbcb1c2f468901326f7231ccc5c3ae2967db2e962f472a39"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"9b874fcd6bfd4c505ac00919830b52b7d8d56574104f465a7f81449775774256","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"e367cfb049fa3ef37cd477a91d92307f4b340ef68eb21edfc8c5d0dfbe56d820","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"5xh3Mvx4QBcI3o3jW7n3a6E4cB_5-6oCvv_0zwmtzQZyLtPSGSyrS6JcuxeQTd0JZgW121MspITu4JlUKusAAw"},"schema":"pubphys.envelope/1"},"record_hash":"9b874fcd6bfd4c505ac00919830b52b7d8d56574104f465a7f81449775774256","leaf_index":1443}