Unsteady flow around impacting bluff bodies
Identifieur interne : 008948 ( Main/Exploration ); précédent : 008947; suivant : 008949Unsteady flow around impacting bluff bodies
Auteurs : T. Leweke [France] ; L. Schouveiler [France] ; M. C. Thompson [Australie] ; K. Hourigan [Australie]Source :
- Journal of fluids and structures [ 0889-9746 ] ; 2008.
Descripteurs français
- Pascal (Inist)
- Ecoulement instationnaire, Rebond, Incidence normale, Paire tourbillon, Effet paroi, Vorticité, Ecoulement tourbillonnaire, Nombre Reynolds, Etirement, Corps arête vive, Fluide visqueux, Cylindre circulaire, Sphère, Symétrie axiale, Longueur onde, Structure turbulence, Ecoulement bidimensionnel, Incidence oblique.
English descriptors
- KwdEn :
Abstract
The flow resulting from the collision without rebound of generic bluff bodies with a wall in a still viscous fluid is investigated both computationally and experimentally. Emphasis is on the case of a circular cylinder impact (two-dimensional geometry), but comparisons with the flow generated by the impact of a sphere (axisymmetric geometry) are included. For normal cylinder impacts, the two counter-rotating vortices forming behind the body during its motion continue their trajectory towards the wall after the collision, leading to the generation of opposite-signed secondary vorticity at the cylinder and wall surfaces. Secondary vortices forming from this vorticity at higher Reynolds numbers exhibit a short-wavelength three-dimensional instability. Comparison with the sphere impact reveals significant differences in the scales of the vortices after the collision, due to the additional vortex stretching acting in the axisymmetric geometry. This leads to a delay in the onset of three-dimensionality and to a different instability mechanism. Oblique cylinder impacts are also considered. For increasing impact angles, the wall effect is gradually reduced on one side of the cylinder, which favours the roll-up of the secondary vorticity and increases the rebound height of the vortex system.
Affiliations:
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Leweke</name><affiliation wicri:level="4"><inist:fA14 i1="01"><s1>Institut de Recherche sur les Phénomènes Hors Équilibre ¯ CNRS, École Centrale, Aix-Marseille Université, 49 rue Frédéric Joliot-Curie, B.P. 146</s1><s2>13384 Marseille</s2><s3>FRA</s3><sZ>1 aut.</sZ><sZ>2 aut.</sZ></inist:fA14><country>France</country><placeName><region type="region" nuts="2">Provence-Alpes-Côte d'Azur</region><settlement type="city">Marseille</settlement><settlement type="city">Marseille</settlement></placeName><orgName type="university">Université d'Aix-Marseille</orgName></affiliation></author><author><name sortKey="Schouveiler, L" sort="Schouveiler, L" uniqKey="Schouveiler L" first="L." last="Schouveiler">L. Schouveiler</name><affiliation wicri:level="4"><inist:fA14 i1="01"><s1>Institut de Recherche sur les Phénomènes Hors Équilibre ¯ CNRS, École Centrale, Aix-Marseille Université, 49 rue Frédéric Joliot-Curie, B.P. 146</s1><s2>13384 Marseille</s2><s3>FRA</s3><sZ>1 aut.</sZ><sZ>2 aut.</sZ></inist:fA14><country>France</country><wicri:noRegion>13384 Marseille</wicri:noRegion><placeName><settlement type="city">Marseille</settlement><region type="région" nuts="2">Provence-Alpes-Côte d'Azur</region><settlement type="city">Marseille</settlement></placeName><orgName type="university">Université d'Aix-Marseille</orgName></affiliation></author><author><name sortKey="Thompson, M C" sort="Thompson, M C" uniqKey="Thompson M" first="M. C." last="Thompson">M. C. Thompson</name><affiliation wicri:level="1"><inist:fA14 i1="02"><s1>Fluids Laboratory for Aeronautical and Industrial Research, Department of Mechanical and Aerospace Engineering, Monash University</s1><s2>Victoria 3800</s2><s3>AUS</s3><sZ>3 aut.</sZ><sZ>4 aut.</sZ></inist:fA14><country>Australie</country><wicri:noRegion>Victoria 3800</wicri:noRegion></affiliation></author><author><name sortKey="Hourigan, K" sort="Hourigan, K" uniqKey="Hourigan K" first="K." last="Hourigan">K. Hourigan</name><affiliation wicri:level="1"><inist:fA14 i1="02"><s1>Fluids Laboratory for Aeronautical and Industrial Research, Department of Mechanical and Aerospace Engineering, Monash University</s1><s2>Victoria 3800</s2><s3>AUS</s3><sZ>3 aut.</sZ><sZ>4 aut.</sZ></inist:fA14><country>Australie</country><wicri:noRegion>Victoria 3800</wicri:noRegion></affiliation><affiliation wicri:level="1"><inist:fA14 i1="03"><s1>Division of Biological Engineering, Monash University</s1><s2>Victoria 3800</s2><s3>AUS</s3><sZ>4 aut.</sZ></inist:fA14><country>Australie</country><wicri:noRegion>Victoria 3800</wicri:noRegion></affiliation></author></analytic><series><title level="j" type="main">Journal of fluids and structures</title><title level="j" type="abbreviated">J. fluids struct.</title><idno type="ISSN">0889-9746</idno><imprint><date when="2008">2008</date></imprint></series></biblStruct></sourceDesc><seriesStmt><title level="j" type="main">Journal of fluids and structures</title><title level="j" type="abbreviated">J. fluids struct.</title><idno type="ISSN">0889-9746</idno></seriesStmt></fileDesc><profileDesc><textClass><keywords scheme="KwdEn" xml:lang="en"><term>Axial symmetry</term><term>Bluff body</term><term>Circular cylinder</term><term>Normal incidence</term><term>Oblique incidence</term><term>Rebound</term><term>Reynolds number</term><term>Spheres</term><term>Stretching</term><term>Turbulence structure</term><term>Two dimensional flow</term><term>Unsteady flow</term><term>Viscous fluids</term><term>Vortex flow</term><term>Vortex pair</term><term>Vorticity</term><term>Wall effects</term><term>Wavelengths</term></keywords><keywords scheme="Pascal" xml:lang="fr"><term>Ecoulement instationnaire</term><term>Rebond</term><term>Incidence normale</term><term>Paire tourbillon</term><term>Effet paroi</term><term>Vorticité</term><term>Ecoulement tourbillonnaire</term><term>Nombre Reynolds</term><term>Etirement</term><term>Corps arête vive</term><term>Fluide visqueux</term><term>Cylindre circulaire</term><term>Sphère</term><term>Symétrie axiale</term><term>Longueur onde</term><term>Structure turbulence</term><term>Ecoulement bidimensionnel</term><term>Incidence oblique</term></keywords></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">The flow resulting from the collision without rebound of generic bluff bodies with a wall in a still viscous fluid is investigated both computationally and experimentally. Emphasis is on the case of a circular cylinder impact (two-dimensional geometry), but comparisons with the flow generated by the impact of a sphere (axisymmetric geometry) are included. For normal cylinder impacts, the two counter-rotating vortices forming behind the body during its motion continue their trajectory towards the wall after the collision, leading to the generation of opposite-signed secondary vorticity at the cylinder and wall surfaces. Secondary vortices forming from this vorticity at higher Reynolds numbers exhibit a short-wavelength three-dimensional instability. Comparison with the sphere impact reveals significant differences in the scales of the vortices after the collision, due to the additional vortex stretching acting in the axisymmetric geometry. This leads to a delay in the onset of three-dimensionality and to a different instability mechanism. Oblique cylinder impacts are also considered. For increasing impact angles, the wall effect is gradually reduced on one side of the cylinder, which favours the roll-up of the secondary vorticity and increases the rebound height of the vortex system.</div></front></TEI><affiliations><list><country><li>Australie</li><li>France</li></country><region><li>Provence-Alpes-Côte d'Azur</li></region><settlement><li>Marseille</li></settlement><orgName><li>Université d'Aix-Marseille</li></orgName></list><tree><country name="France"><region name="Provence-Alpes-Côte d'Azur"><name sortKey="Leweke, T" sort="Leweke, T" uniqKey="Leweke T" first="T." last="Leweke">T. Leweke</name></region><name sortKey="Schouveiler, L" sort="Schouveiler, L" uniqKey="Schouveiler L" first="L." last="Schouveiler">L. Schouveiler</name></country><country name="Australie"><noRegion><name sortKey="Thompson, M C" sort="Thompson, M C" uniqKey="Thompson M" first="M. C." last="Thompson">M. C. Thompson</name></noRegion><name sortKey="Hourigan, K" sort="Hourigan, K" uniqKey="Hourigan K" first="K." last="Hourigan">K. Hourigan</name><name sortKey="Hourigan, K" sort="Hourigan, K" uniqKey="Hourigan K" first="K." last="Hourigan">K. Hourigan</name></country></tree></affiliations></record>Pour manipuler ce document sous Unix (Dilib)
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