{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,8]],"date-time":"2025-12-08T22:08:48Z","timestamp":1765231728742,"version":"3.41.2"},"reference-count":41,"publisher":"AIP Publishing","issue":"9","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2007,9,1]]},"abstract":"<jats:p>Experimental observations and numerical simulations, based upon the Phan-Thien and Tanner model, are reported for the laminar flow of a series of viscoelastic liquids (0.05%, 0.1%, and 0.4% concentrations of a polyacrylamide) over a symmetrical, double backward-facing step geometry preceded by a short gradual contraction from a long (120 hydraulic diameters in length) square duct. Reynolds numbers are typically between 10 and 100 (i.e., inertia is not negligible) and Deborah numbers of order 100 for the experiments (based on a relaxation time determined from linear viscoelasticity measurements) and order 10 for the viscoelastic simulations. As the polymer concentration is increased, the combined effects of increased shear thinning and viscoelasticity are found to dramatically reduce the length of the recirculation region downstream of the step. The nature of the flow field within the contraction itself is found to be fundamentally different for the viscoelastic liquids to that for a comparable Newtonian fluid flow: large velocity overshoots with very strong gradients appear near to the sidewalls that, due to their appearance, we have dubbed \u201ccat\u2019s ears.\u201d The simulations are able to reproduce these remarkable features, at least qualitatively.<\/jats:p>","DOI":"10.1063\/1.2769380","type":"journal-article","created":{"date-parts":[[2007,9,25]],"date-time":"2007-09-25T22:11:17Z","timestamp":1190758277000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":20,"title":["Laminar flow of a viscoelastic shear-thinning liquid over a backward-facing step preceded by a gradual contraction"],"prefix":"10.1063","volume":"19","author":[{"given":"R. J.","family":"Poole","sequence":"first","affiliation":[{"name":"University of Liverpool Department of Engineering, , Brownlow Hill, Liverpool L69 3GH, United Kingdom"}]},{"given":"M. P.","family":"Escudier","sequence":"additional","affiliation":[{"name":"University of Liverpool Department of Engineering, , Brownlow Hill, Liverpool L69 3GH, United Kingdom"}]},{"given":"A.","family":"Afonso","sequence":"additional","affiliation":[{"name":"Universidade do Porto Centro de Estudos de Fen\u00f3menos de Transporte, DEMEGI, Faculdade de Engenharia, , Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal"}]},{"given":"F. T.","family":"Pinho","sequence":"additional","affiliation":[{"name":"Universidade do Porto Centro de Estudos de Fen\u00f3menos de Transporte, Faculdade de Engenharia, , Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal and , Largo do Pa\u00e7o, 4704-553 Braga, Portugal"},{"name":"Universidade do Minho Centro de Estudos de Fen\u00f3menos de Transporte, Faculdade de Engenharia, , Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal and , Largo do Pa\u00e7o, 4704-553 Braga, Portugal"}]}],"member":"317","published-online":{"date-parts":[[2007,9,25]]},"reference":[{"key":"2023062814503728500_c1","doi-asserted-by":"publisher","first-page":"111","DOI":"10.1017\/S0022112074002035","article-title":"Low Reynolds number flow over a plane sudden expansion","volume":"64","year":"1974","journal-title":"J. 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