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Auteur M. F. Tachie |
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Ajouter le résultat dans votre panier Faire une suggestion Affiner la rechercheCharacteristics of turbulent three-dimensional offset jets / Agelin-Chaab, M. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011)
Titre : Characteristics of turbulent three-dimensional offset jets Type de document : texte imprimé Auteurs : Agelin-Chaab, M., Auteur ; M. F. Tachie, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Boundary layer turbulence Flow separation visualisation Fractals Jets Shear Wetting Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional turbulent offset jets were investigated using a particle image velocimetry technique. Three jet exit Reynolds numbers, Rej = 5000, 10,000, and 20,000, and four offset heights, h/d = 0.5, 1.0, 2.0, and 4.0, were studied. The mean flow and turbulence statistics were studied over larger downstream distances than in previous studies. The decay and spread rates were found to be nearly independent of Reynolds number and offset height at certain exit diameters (x = 73d) downstream and h/d DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 09 p.[article] Characteristics of turbulent three-dimensional offset jets [texte imprimé] / Agelin-Chaab, M., Auteur ; M. F. Tachie, Auteur . - 2011 . - 09 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 09 p.
Mots-clés : Boundary layer turbulence Flow separation visualisation Fractals Jets Shear Wetting Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional turbulent offset jets were investigated using a particle image velocimetry technique. Three jet exit Reynolds numbers, Rej = 5000, 10,000, and 20,000, and four offset heights, h/d = 0.5, 1.0, 2.0, and 4.0, were studied. The mean flow and turbulence statistics were studied over larger downstream distances than in previous studies. The decay and spread rates were found to be nearly independent of Reynolds number and offset height at certain exit diameters (x = 73d) downstream and h/d DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] Exemplaires
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Titre : Characteristics of turbulent three-dimensional wall jets Type de document : texte imprimé Auteurs : Agelin-Chaab, M., Auteur ; M. F. Tachie, Auteur Année de publication : 2011 Article en page(s) : 12 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Boundary layer turbulence Correlation methods Flow visualisation Jets Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional turbulent wall jet was investigated using a particle image velocimetry technique. Three Reynolds numbers based on the jet exit velocity and diameter of 5000, 10,000, and 20,000 were studied. Profiles of the mean velocities, turbulence intensities, and Reynolds shear stresses as well as two-point velocity correlations and proper orthogonal decomposition analyses were used to document the salient features of the wall jets. The decay and spread rates are independent of Reynolds numbers in the self-similar region. The estimated values of 1.15, 0.054, and 0.255 for the decay rate, wall-normal spread rate, and lateral spread rate, respectively, are within the range of values reported in the literature. The two-point correlation analysis showed that the inclination of the streamwise velocity correlation contours in the inner layer is 11±3 deg in the wall region, which is similar to those of canonical turbulent boundary layers. The results from the proper orthogonal decomposition indicate that low-order modes contribute more to the turbulence statistics in the self-similar region than in the developing region. The Reynolds shear stresses are the biggest benefactors of the low-order mode contribution while the wall-normal turbulence intensities are the least. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 12 p.[article] Characteristics of turbulent three-dimensional wall jets [texte imprimé] / Agelin-Chaab, M., Auteur ; M. F. Tachie, Auteur . - 2011 . - 12 p.
Fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 12 p.
Mots-clés : Boundary layer turbulence Correlation methods Flow visualisation Jets Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional turbulent wall jet was investigated using a particle image velocimetry technique. Three Reynolds numbers based on the jet exit velocity and diameter of 5000, 10,000, and 20,000 were studied. Profiles of the mean velocities, turbulence intensities, and Reynolds shear stresses as well as two-point velocity correlations and proper orthogonal decomposition analyses were used to document the salient features of the wall jets. The decay and spread rates are independent of Reynolds numbers in the self-similar region. The estimated values of 1.15, 0.054, and 0.255 for the decay rate, wall-normal spread rate, and lateral spread rate, respectively, are within the range of values reported in the literature. The two-point correlation analysis showed that the inclination of the streamwise velocity correlation contours in the inner layer is 11±3 deg in the wall region, which is similar to those of canonical turbulent boundary layers. The results from the proper orthogonal decomposition indicate that low-order modes contribute more to the turbulence statistics in the self-similar region than in the developing region. The Reynolds shear stresses are the biggest benefactors of the low-order mode contribution while the wall-normal turbulence intensities are the least. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] Exemplaires
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Titre : Experimental and numerical study of laminar round jet flows along a wall Type de document : texte imprimé Auteurs : K. F. K. Adane, Auteur ; M. F. Tachie, Auteur Année de publication : 2011 Article en page(s) : 10 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow (dynamics) measurement Reynolds number jets vorticity Résumé : In the present study, both experimental and numerical techniques were employed to study three-dimensional laminar wall jet flows. The wall jet was created using a circular pipe of diameter 7×10−3 m and flows into an open water tank. The inlet Reynolds numbers based on the pipe diameter and jet exit velocity were 310 and 800. A particle image velocimetry (PIV) was used to conduct detailed measurements at various streamwise-transverse and streamwise-spanwise planes. The complete nonlinear incompressible Navier–Stokes equation was also solved using a collocated finite volume based in-house computational fluid dynamics (CFD) code. The computation was performed for three inlet Reynolds numbers, namely, 310, 420, and 800. From the PIV measurements and CFD results, velocity profiles and jet half-widths were extracted at selected downstream locations. It was observed that the numerical results are in reasonable agreement with the experimental data. The distributions of the velocities, jet spread rates, and vorticity were used to provide insight into the characteristics of three-dimensional laminar wall jet flows. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27433 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 10 (Octobre 2010) . - 10 p.[article] Experimental and numerical study of laminar round jet flows along a wall [texte imprimé] / K. F. K. Adane, Auteur ; M. F. Tachie, Auteur . - 2011 . - 10 p.
fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 10 (Octobre 2010) . - 10 p.
Mots-clés : flow (dynamics) measurement Reynolds number jets vorticity Résumé : In the present study, both experimental and numerical techniques were employed to study three-dimensional laminar wall jet flows. The wall jet was created using a circular pipe of diameter 7×10−3 m and flows into an open water tank. The inlet Reynolds numbers based on the pipe diameter and jet exit velocity were 310 and 800. A particle image velocimetry (PIV) was used to conduct detailed measurements at various streamwise-transverse and streamwise-spanwise planes. The complete nonlinear incompressible Navier–Stokes equation was also solved using a collocated finite volume based in-house computational fluid dynamics (CFD) code. The computation was performed for three inlet Reynolds numbers, namely, 310, 420, and 800. From the PIV measurements and CFD results, velocity profiles and jet half-widths were extracted at selected downstream locations. It was observed that the numerical results are in reasonable agreement with the experimental data. The distributions of the velocities, jet spread rates, and vorticity were used to provide insight into the characteristics of three-dimensional laminar wall jet flows. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27433 [...] Exemplaires
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Titre : Numerical investigation of flow recirculation in a draft tube Titre original : Etude numérique de la recirculation dans une chambre d'aspiration Type de document : texte imprimé Auteurs : Adane, K. K., Auteur ; Ormiston, S. J., Auteur ; M. F. Tachie, Auteur Année de publication : 2008 Article en page(s) : 15-20 p. Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Draft tube Numerical analysis Turbulent flow Inflow slots Chambre d'aspiration Analyse numérique Écoulement turbulent Fentes d'apport Index. décimale : 627 Ingénierie des cours d'eau naturels, des ports, des rades et des cotes. Installations de navigation, de dragage, de récupération et de sauvetage. Barrages et centrales électriques hydrauliques Résumé : A numerical investigation of turbulent flow in a draft tube with and without an opening (slot) in the top of each of its three outlet channels is presented. A commercial CFD code, CFX-5, is used to solve the Reynolds-averaged Navier-Stokes equations and a standard k-ε turbulence model with a scalable wall-function. The case for no slots was compared with the cases of three mass flow rates into the slots. The results demonstrate that values of the overall pressure coefficient and velocity head obtained for various slot mass flow rates are not significantly different. The flow into the slots, however, creates different amounts of localised recirculation and backflow in the individual outlet channels formed between the two pier noses.
Cet article présente une étude numérique de l'écoulement turbulent dans une chambre d'aspiration tube avec et sans une ouverture (fente) dans le dessus de chacun de ses trois canaux de sortie. Un code commercial de CFD, CFX-5, est employé pour résoudre Reynolds-fait la moyenne Navier-Charge des équations et un modèle standard de turbulence de k-ε avec une mur-fonction extensible. La caisse pour aucunes fentes a été comparée aux cas de trois taux d'écoulement de la masse dans les fentes. Les résultats démontrent que les valeurs de la tête globale de coefficient et de vitesse de pression obtenue pour différents taux d'écoulement de la masse de fente ne sont pas sensiblement différentes. L'écoulement dans les fentes, cependant, crée différentes quantités de recyclage et de refoulement localisés dans les différents canaux de sortie formés entre les deux nez de pilier.DEWEY : 627 ISSN : 0022-1686 RAMEAU : Turbulence En ligne : http://www.journalhydraulicresearch.com/
in Journal of hydraulic research > Vol. 46 N°1 (2008) . - 15-20 p.[article] Numerical investigation of flow recirculation in a draft tube = Etude numérique de la recirculation dans une chambre d'aspiration [texte imprimé] / Adane, K. K., Auteur ; Ormiston, S. J., Auteur ; M. F. Tachie, Auteur . - 2008 . - 15-20 p.
Hydraulique
Langues : Anglais (eng)
in Journal of hydraulic research > Vol. 46 N°1 (2008) . - 15-20 p.
Mots-clés : Draft tube Numerical analysis Turbulent flow Inflow slots Chambre d'aspiration Analyse numérique Écoulement turbulent Fentes d'apport Index. décimale : 627 Ingénierie des cours d'eau naturels, des ports, des rades et des cotes. Installations de navigation, de dragage, de récupération et de sauvetage. Barrages et centrales électriques hydrauliques Résumé : A numerical investigation of turbulent flow in a draft tube with and without an opening (slot) in the top of each of its three outlet channels is presented. A commercial CFD code, CFX-5, is used to solve the Reynolds-averaged Navier-Stokes equations and a standard k-ε turbulence model with a scalable wall-function. The case for no slots was compared with the cases of three mass flow rates into the slots. The results demonstrate that values of the overall pressure coefficient and velocity head obtained for various slot mass flow rates are not significantly different. The flow into the slots, however, creates different amounts of localised recirculation and backflow in the individual outlet channels formed between the two pier noses.
Cet article présente une étude numérique de l'écoulement turbulent dans une chambre d'aspiration tube avec et sans une ouverture (fente) dans le dessus de chacun de ses trois canaux de sortie. Un code commercial de CFD, CFX-5, est employé pour résoudre Reynolds-fait la moyenne Navier-Charge des équations et un modèle standard de turbulence de k-ε avec une mur-fonction extensible. La caisse pour aucunes fentes a été comparée aux cas de trois taux d'écoulement de la masse dans les fentes. Les résultats démontrent que les valeurs de la tête globale de coefficient et de vitesse de pression obtenue pour différents taux d'écoulement de la masse de fente ne sont pas sensiblement différentes. L'écoulement dans les fentes, cependant, crée différentes quantités de recyclage et de refoulement localisés dans les différents canaux de sortie formés entre les deux nez de pilier.DEWEY : 627 ISSN : 0022-1686 RAMEAU : Turbulence En ligne : http://www.journalhydraulicresearch.com/ Exemplaires
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Titre : Particle image velocimetry study of rough-wall turbulent flows in favorable pressure gradient Type de document : texte imprimé Auteurs : G. F. K. Tay, Auteur ; D. C. S. Kuhn, Auteur ; M. F. Tachie, Auteur Année de publication : 2009 Article en page(s) : 12 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : turbulence surface roughness pressure gradient Reynolds number stress boundary layers channels (hydraulic engineering) sands flow (dynamics) gravel Résumé : This paper reports an experimental investigation of the effects of wall roughness and favorable pressure gradient on low Reynolds number turbulent flow in a two-dimensional asymmetric converging channel. Flow convergence was produced by means of ramps (of angles 2 deg and 3 deg) installed on the bottom wall of a plane channel. The experiments were conducted over a smooth surface and over transitionally rough and fully rough surfaces produced from sand grains and gravel of nominal mean diameters 1.55 mm and 4.22 mm, respectively. The dimensionless acceleration parameter was varied from 0.38×10−6 to 3.93×10−6 while the Reynolds number based on the boundary layer momentum thickness was varied from 290 to 2250. The velocity measurements were made using a particle image velocimetry technique. From these measurements, the distributions of the mean velocity and Reynolds stresses were obtained to document the salient features of transitionally and fully rough low Reynolds number turbulent boundary layers subjected to favorable pressure gradient. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]
in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 6 (Juin 2009) . - 12 p.[article] Particle image velocimetry study of rough-wall turbulent flows in favorable pressure gradient [texte imprimé] / G. F. K. Tay, Auteur ; D. C. S. Kuhn, Auteur ; M. F. Tachie, Auteur . - 2009 . - 12 p.
fluids engineering
Langues : Anglais (eng)
in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 6 (Juin 2009) . - 12 p.
Mots-clés : turbulence surface roughness pressure gradient Reynolds number stress boundary layers channels (hydraulic engineering) sands flow (dynamics) gravel Résumé : This paper reports an experimental investigation of the effects of wall roughness and favorable pressure gradient on low Reynolds number turbulent flow in a two-dimensional asymmetric converging channel. Flow convergence was produced by means of ramps (of angles 2 deg and 3 deg) installed on the bottom wall of a plane channel. The experiments were conducted over a smooth surface and over transitionally rough and fully rough surfaces produced from sand grains and gravel of nominal mean diameters 1.55 mm and 4.22 mm, respectively. The dimensionless acceleration parameter was varied from 0.38×10−6 to 3.93×10−6 while the Reynolds number based on the boundary layer momentum thickness was varied from 290 to 2250. The velocity measurements were made using a particle image velocimetry technique. From these measurements, the distributions of the mean velocity and Reynolds stresses were obtained to document the salient features of transitionally and fully rough low Reynolds number turbulent boundary layers subjected to favorable pressure gradient. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] Exemplaires
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