{ "id": "2312.14613", "version": "v1", "published": "2023-12-22T11:14:42.000Z", "updated": "2023-12-22T11:14:42.000Z", "title": "Absolute and convective instabilities in a liquid film over a substrate moving against gravity", "authors": [ "Fabio Pino", "Miguel Alfonso Mendez", "Benoit Scheid" ], "categories": [ "physics.flu-dyn" ], "abstract": "The drag-out problem for small Reynolds numbers (Re) admits the Landau-Levich-Derjaguin (LLD) solution for small capillary numbers (Ca), and Derjaguin's solution for large Ca. We investigate whether these solutions are absolutely or convectively unstable, solving the Orr-Sommerfeld eigenvalue problem. For Derjaguin's solution, we show that the instability is unconditionally convective for Kapitza number (Ka) smaller than 17 and becomes absolute for Ka>0.15 and Re^(1.7) for Re>10. For water (Ka=3400), the LLD solution is always convectively unstable. The absolute instability is observed only when the dip-coated film is additionally fed from above.", "revisions": [ { "version": "v1", "updated": "2023-12-22T11:14:42.000Z" } ], "analyses": { "keywords": [ "liquid film", "convective instabilities", "substrate moving", "derjaguins solution", "orr-sommerfeld eigenvalue problem" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }