{"paper":{"title":"On the shear-current effect: toward understanding why theories and simulations have mutually and separately conflicted","arxiv_id":"2104.11112","primary_cat":"physics.flu-dyn","submitted_at":"2021-04-22T15:00:33+00:00","version_compiled":"v2"},"notice":"Every quoted sentence is the authors' text from the arXiv listing abstract. Labels and probabilities are the outputs of classifier-1.13.0 on the question bank abstract-p1-20260923, exactly as returned. No sentence in this record was written by a language model.","schema":"pith.compiled-record/v0","status":"compiled","abstract":{"source":"arXiv listing abstract v2","sentences":[{"i":0,"p":1.0,"id":"s0","own":false,"role":"background","text":"The shear-current effect (SCE) of mean-field dynamo theory refers to the combination of a shear flow and a turbulent coefficient $\\beta_{21}$ with a favorable negative sign for exponential mean-field growth, rather than positive for diffusion.","hedge":{"p":0.99,"label":"asserted"},"own_p":0.06,"main_claim_p":0.07,"quantitative":false,"quantitative_p":0.21,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.0,"background":1.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":1,"p":0.76,"id":"s1","own":false,"role":"background","text":"There have been long standing disagreements among theoretical calculations and comparisons of theory with numerical experiments as to the sign of kinetic ($\\beta^u_{21}$) and magnetic ($\\beta^b_{21}$) contributions.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.04,"main_claim_p":0.03,"quantitative":false,"quantitative_p":0.14,"role_probabilities":{"gap":0.24,"method":0.0,"result":0.0,"background":0.76,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":2,"p":0.75,"id":"s2","own":true,"role":"result","text":"To resolve these discrepancies, we combine an analytical approach with simulations, and show that unlike $\\beta^b_{21}$, the kinetic SCE $\\beta^u_{21}$ has a strong dependence on the kinetic energy spectral index and can transit from positive to negative values at $\\mathcal{O}(10)$ Reynolds numbers if the spectrum is not too steep.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.96,"main_claim_p":0.67,"quantitative":true,"quantitative_p":0.95,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.75,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.25,"interpretation":0.0}},{"i":3,"p":1.0,"id":"s3","own":true,"role":"result","text":"Conversely, $\\beta^b_{21}$ is always negative regardless of the spectral index and Reynolds numbers.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.85,"main_claim_p":0.18,"quantitative":true,"quantitative_p":0.59,"role_probabilities":{"gap":0.0,"method":0.0,"result":1.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":4,"p":0.96,"id":"s4","own":true,"role":"result","text":"For very steep energy spectra, the positive $\\beta^u_{21}$ can dominate even at energy equipartition $u_\\text{rms}\\simeq b_\\text{rms}$, resulting in a positive total $\\beta_{21}$ even though $\\beta^b_{21}<0$.","hedge":{"p":0.91,"label":"asserted"},"own_p":0.87,"main_claim_p":0.13,"quantitative":true,"quantitative_p":0.92,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.96,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.04}},{"i":5,"p":0.92,"id":"s5","own":true,"role":"interpretation","text":"Our findings bridge the gap between the seemingly contradictory results from the second-order-correlation approximation (SOCA) versus the spectral-$\\tau$ closure (STC), for which opposite signs for $\\beta^u_{21}$ have been reported, with the same sign for $\\beta^b_{21}<0$.","hedge":{"p":0.99,"label":"asserted"},"own_p":0.72,"main_claim_p":0.27,"quantitative":true,"quantitative_p":0.53,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.05,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.03,"interpretation":0.92}},{"i":6,"p":0.97,"id":"s6","own":true,"role":"interpretation","text":"The results also offer an explanation for the simulations that find $\\beta^u_{21}>0$ and an inconclusive overall sign of $\\beta_{21}$ for $\\mathcal{O}(10)$ Reynolds numbers.","hedge":{"p":0.67,"label":"asserted"},"own_p":0.56,"main_claim_p":0.12,"quantitative":true,"quantitative_p":0.79,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.02,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.01,"interpretation":0.97}},{"i":7,"p":0.88,"id":"s7","own":true,"role":"method","text":"The transient behavior of $\\beta^u_{21}$ is demonstrated using the kinematic test-field method.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.93,"main_claim_p":0.03,"quantitative":false,"quantitative_p":0.04,"role_probabilities":{"gap":0.0,"method":0.88,"result":0.08,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.04,"interpretation":0.0}},{"i":8,"p":0.76,"id":"s8","own":true,"role":"future_work","text":"We compute dynamo growth rates for cases with or without rotation, and discuss opportunities for further work.","hedge":{"p":0.83,"label":"asserted"},"own_p":0.92,"main_claim_p":0.04,"quantitative":false,"quantitative_p":0.11,"role_probabilities":{"gap":0.0,"method":0.01,"result":0.03,"background":0.0,"limitation":0.0,"future_work":0.76,"contribution":0.2,"interpretation":0.0}}]},"compiled":{"main_claim":{"p":0.72,"text":"To resolve these discrepancies, we combine an analytical approach with simulations, and show that unlike $\\beta^b_{21}$, the kinetic SCE $\\beta^u_{21}$ has a strong dependence on the kinetic energy spectral index and can transit from positive to negative values at $\\mathcal{O}(10)$ Reynolds numbers if the spectrum is not too steep.","location":"abstract s2","hedge_strength":{"p":1.0,"label":"asserted"}},"provenance":{"route":{"via":"TypeSafe API","model":"classifier-1.13.0","endpoint":"https://api.typesafe.ai/v1/systemone","provider":"TypeSafe"},"packing":"one request per 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