[Observation expérimentale de doublement de fréquence dans la couche de mélange viscoélastique.]
Une étude expérimentale de la couche de mélange à un nombre de Reynolds de 440 est réalisée. Une solution viscoélastique colorée est introduite dans la couche cisaillée stationnaire juste avant la formation des tourbillons. En utilisant un mesure locale de la vitesse et une technique de visualisation par fluorescence, il est montré que la formation tourbillonnaire est affectée par le comportement non-Newtonien de la solution viscoélastique par rapport au cas Newtonien. Cet effet correspond à la formation de tourbillons secondaires produisant un harmonique supérieur dans la répartition spatiale de vorticité. En conséquence, un doublement de la fréquence des oscillations de la vitesse locale dans la couche de mélange est observé.
An experimental mixing layer in water at Reynolds number 440 is investigated. A colored viscoelastic solution is introduced in the shear layer before the roll-up dynamics. On the basis of flow visualization and local velocity measurements, it is found that compared to the Newtonian case, the roll-up process is affected by the non-Newtonian behavior of the viscoelastic solution. The effect consists of the appearance of secondary eddies in the mixing layer corresponding to the production of higher harmonics in the vorticity distribution. Consequently, there is a frequency doubling of the local velocity oscillations in the mixing layer.
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Mots-clés : Mécanique des fluides, Couche de mélange, Élasticité, Production d'harmoniques
F. Sausset 1 ; O. Cadot 1 ; S. Kumar 2
@article{CRMECA_2004__332_12_1001_0, author = {F. Sausset and O. Cadot and S. Kumar}, title = {Experimental observation of frequency doubling in a viscoelastic mixing layer}, journal = {Comptes Rendus. M\'ecanique}, pages = {1001--1006}, publisher = {Elsevier}, volume = {332}, number = {12}, year = {2004}, doi = {10.1016/j.crme.2004.10.001}, language = {en}, }
TY - JOUR AU - F. Sausset AU - O. Cadot AU - S. Kumar TI - Experimental observation of frequency doubling in a viscoelastic mixing layer JO - Comptes Rendus. Mécanique PY - 2004 SP - 1001 EP - 1006 VL - 332 IS - 12 PB - Elsevier DO - 10.1016/j.crme.2004.10.001 LA - en ID - CRMECA_2004__332_12_1001_0 ER -
F. Sausset; O. Cadot; S. Kumar. Experimental observation of frequency doubling in a viscoelastic mixing layer. Comptes Rendus. Mécanique, Volume 332 (2004) no. 12, pp. 1001-1006. doi : 10.1016/j.crme.2004.10.001. https://comptes-rendus.academie-sciences.fr/mecanique/articles/10.1016/j.crme.2004.10.001/
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