{"paper":{"title":"Dynamic similarity of vortex shedding in a superfluid flowing past a penetrable obstacle","license":"http://creativecommons.org/licenses/by/4.0/","headline":"A superfluid Reynolds number built from the supersonic region around a penetrable obstacle collapses wake patterns and drag across different obstacle sizes.","cross_cats":["physics.flu-dyn"],"primary_cat":"cond-mat.quant-gas","authors_text":"Junhwan Kwon, Y. Shin","submitted_at":"2026-02-03T13:36:20Z","abstract_excerpt":"We numerically investigate wake dynamics in a superfluid flowing past a penetrable obstacle. Unlike an impenetrable object, a penetrable obstacle does not fully deplete the density. We define an effective diameter $D_{\\rm eff}$ from the Mach-1 contour of the time-averaged irrotational flow around the obstacle, which delineates the local supersonic region where quantized vortices nucleate. Using this flow-defined length scale, we construct a superfluid Reynolds number $Re_{\\rm s} = (v_0 - v_c) D_{\\rm eff}/ (\\hbar/ m)$, where $v_0$ is the flow speed, $v_c$ is the critical velocity, and m is the "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"Using this flow-defined length scale, we construct a superfluid Reynolds number Re_s = (v_0 - v_c) D_eff / (ℏ/m) ... We show that Re_s organizes the wake dynamics across obstacle sizes and strengths: the transition from dipole-row emission to alternating vortex cluster shedding occurs at Re_s around 2, and both the Strouhal number and the drag coefficient collapse onto universal curves when plotted as functions of Re_s.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the Mach-1 contour of the time-averaged irrotational flow accurately delineates the region where quantized vortices nucleate and that subtracting v_c yields a dynamically meaningful velocity scale independent of specific numerical details or obstacle modeling choices.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"A superfluid Reynolds number defined from the Mach-1 contour of the irrotational flow organizes wake dynamics for penetrable obstacles, with shedding transition at Re_s ~2 and collapse of Strouhal number and drag coefficient.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"A superfluid Reynolds number built from the supersonic region around a penetrable obstacle collapses wake patterns and drag across different obstacle sizes.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"0dad7a803e563cd3ce4d367adaeb4e6ee2d5cdc8a74f45654a70689313576626"},"source":{"id":"2602.03518","kind":"arxiv","version":2},"verdict":{"id":"2497a031-2e2c-4f79-b138-b052bb74c04a","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-16T07:44:45.448111Z","strongest_claim":"Using this flow-defined length scale, we construct a superfluid Reynolds number Re_s = (v_0 - v_c) D_eff / (ℏ/m) ... We show that Re_s organizes the wake dynamics across obstacle sizes and strengths: the transition from dipole-row emission to alternating vortex cluster shedding occurs at Re_s around 2, and both the Strouhal number and the drag coefficient collapse onto universal curves when plotted as functions of Re_s.","one_line_summary":"A superfluid Reynolds number defined from the Mach-1 contour of the irrotational flow organizes wake dynamics for penetrable obstacles, with shedding transition at Re_s ~2 and collapse of Strouhal number and drag coefficient.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the Mach-1 contour of the time-averaged irrotational flow accurately delineates the region where quantized vortices nucleate and that subtracting v_c yields a dynamically meaningful velocity scale independent of specific numerical details or obstacle modeling choices.","pith_extraction_headline":"A superfluid Reynolds number built from the supersonic region around a penetrable obstacle collapses wake patterns and drag across different obstacle sizes."},"references":{"count":63,"sample":[{"doi":"","year":2000,"title":"G. K. Batchelor,An Introduction to Fluid Dynamics (Cambridge University Press, England, 2000)","work_id":"f93fb4ba-d3ce-4854-bd22-acb3205afb50","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":1953,"title":"Roshko, On the development of turbulent wakes from vortex streets, National Advisory Committee for Aero- nautics Technical Note 1191, California Institute of Tech- nology, 1953","work_id":"530722bf-53c3-4a1a-bfe3-821b601633ab","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":1987,"title":"M. Provansal, C. Mathis, and L. Boyer, B´ enard–von K´ arm´ an instability: transient and forced regimes, J. Fluid Mech.182, 1 (1987)","work_id":"bdaf7060-542f-4311-97c9-f512a284c68c","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":1966,"title":"J. H. Lienhard, Synopsis of lift, drag, and vortex fre- quency data for rigid circular cylinders, inTechnical Ex- tension Service(Washington State university, Bulletin, 1966)","work_id":"53c49f50-f8c3-453e-9842-07cd0f479453","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":1961,"title":"A. Roshko, Experiments on the flow past a circular cylin- der at very high Reynolds number, J. Fluid Mech.10, 345 (1961)","work_id":"be9021bf-b931-41cc-ba14-ec747788d4d8","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":63,"snapshot_sha256":"fd2ca5ca754947a7726c0b78aaa4a402d3c9583374886e5ec46e8590dcaf2728","internal_anchors":0},"formal_canon":{"evidence_count":2,"snapshot_sha256":"399125ecd87dd43007f225b875145ca3832b5544d8ccb3e90d48514189d23df6"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}