Documents disponibles écrits par cet auteur

Characteristics of turbulent three-dimensional offset jets / Agelin-Chaab, M. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 09 p. Titre : Characteristics of turbulent three-dimensional offset jets Type de document : texte imprimé Auteurs : Agelin-Chaab, M., Auteur ; Tachie, M. F., 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  Flow  visualisation  Fractals  Jets  Shear  turbulence  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 <= 2. The decay rates of 1.18 ± 0.03 and spread rates of 0.055 ± 0.001 and 0.250 ± 0.005 in the wall-normal and lateral directions were obtained, respectively. The reattachment lengths are also independent of Rej but increase with offset height. The locations of the maximum mean velocities increased linearly with streamwise distance in the self-similar region. It was observed that profiles of the mean velocities, turbulence intensities, and Reynolds shears stresses are nearly independent of Rej and h/d far downstream. The triple products in the symmetry plane indicated turbulence transport from the outer region of the jet towards the wall region. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Characteristics of turbulent three-dimensional offset jets [texte imprimé] / Agelin-Chaab, M., Auteur ; Tachie, M. F., 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  Flow  visualisation  Fractals  Jets  Shear  turbulence  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 <= 2. The decay rates of 1.18 ± 0.03 and spread rates of 0.055 ± 0.001 and 0.250 ± 0.005 in the wall-normal and lateral directions were obtained, respectively. The reattachment lengths are also independent of Rej but increase with offset height. The locations of the maximum mean velocities increased linearly with streamwise distance in the self-similar region. It was observed that profiles of the mean velocities, turbulence intensities, and Reynolds shears stresses are nearly independent of Rej and h/d far downstream. The triple products in the symmetry plane indicated turbulence transport from the outer region of the jet towards the wall region. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Characteristics of turbulent three-dimensional wall jets / Agelin-Chaab, M. in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 12 p. Titre : Characteristics of turbulent three-dimensional wall jets Type de document : texte imprimé Auteurs : Agelin-Chaab, M., Auteur ; Tachie, M. F., 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 [...] [article] Characteristics of turbulent three-dimensional wall jets [texte imprimé] / Agelin-Chaab, M., Auteur ; Tachie, M. F., 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 [...]

Numerical investigation of flow recirculation in a draft tube / Adane, K. K. in Journal of hydraulic research, Vol. 46 N°1 (2008) 

Public ISBD [article]  in Journal of hydraulic research > Vol. 46 N°1 (2008) . - 15-20 p. 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 ; Tachie, M. F., Auteur 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/ [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 ; Tachie, M. F., Auteur . - 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/

Particle image velocimetry study of rough-wall turbulent flows in favorable pressure gradient / G. F. K. Tay in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 6 (Juin 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 6 (Juin 2009) . - 12 p. 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 ; Tachie, M. F., 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 [...] [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 ; Tachie, M. F., 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 [...]

PIV study of adverse and favorable pressure gradient turbulent flows over transverse ribs / M. Agelinchaab in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 11 (Novembre 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 11 (Novembre 2008) . - 12 p. Titre : PIV study of adverse and favorable pressure gradient turbulent flows over transverse ribs Type de document : texte imprimé Auteurs : M. Agelinchaab, Auteur ; Tachie, M. F., Auteur Année de publication : 2009 Article en page(s) : 12 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Flow  (Dynamics);  turbulence;  boundary  layers;  pressure  gradient;  surface  roughness;  stress;  channels  (Hydraulic  engineering);  cavities Résumé : This paper reports an experimental study of the combined effects of rib roughness and pressure gradient on turbulent flows produced in asymmetric converging and diverging channels. Transverse square ribs with pitch-to-height ratio of 4 were attached to the bottom wall of the channel to produce the rib roughness. A particle image velocimetry technique was used to conduct measurements at several streamwise-transverse planes located upstream, within, and downstream of the converging and diverging sections of the channel. From these measurements, the mean velocities and turbulent statistics at the top plane of the ribs and across the channel were obtained. The data revealed non-negligible wall-normal motion and interaction between the cavities and overlying boundary layers. The different drag characteristics of the rough bottom wall and the smooth top wall produced asymmetric distributions of mean velocity and turbulent statistics across the channel. The asymmetry of these profiles is most extreme in the presence of adverse pressure gradient. Because of the manner in which pressure gradient modifies the mean flow and turbulence production, it was found that the streamwise turbulence intensity and Reynolds shear stress in the vicinity of the ribs are lower in the adverse pressure gradient than in the favorable pressure gradient channel. The results show also that the combined effects of rib roughness and adverse pressure gradient on the turbulent intensity statistics are significantly higher than when roughness and adverse pressure gradient are applied in isolation. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] PIV study of adverse and favorable pressure gradient turbulent flows over transverse ribs [texte imprimé] / M. Agelinchaab, Auteur ; Tachie, M. F., Auteur . - 2009 . - 12 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 11 (Novembre 2008) . - 12 p. Mots-clés : Flow  (Dynamics);  turbulence;  boundary  layers;  pressure  gradient;  surface  roughness;  stress;  channels  (Hydraulic  engineering);  cavities Résumé : This paper reports an experimental study of the combined effects of rib roughness and pressure gradient on turbulent flows produced in asymmetric converging and diverging channels. Transverse square ribs with pitch-to-height ratio of 4 were attached to the bottom wall of the channel to produce the rib roughness. A particle image velocimetry technique was used to conduct measurements at several streamwise-transverse planes located upstream, within, and downstream of the converging and diverging sections of the channel. From these measurements, the mean velocities and turbulent statistics at the top plane of the ribs and across the channel were obtained. The data revealed non-negligible wall-normal motion and interaction between the cavities and overlying boundary layers. The different drag characteristics of the rough bottom wall and the smooth top wall produced asymmetric distributions of mean velocity and turbulent statistics across the channel. The asymmetry of these profiles is most extreme in the presence of adverse pressure gradient. Because of the manner in which pressure gradient modifies the mean flow and turbulence production, it was found that the streamwise turbulence intensity and Reynolds shear stress in the vicinity of the ribs are lower in the adverse pressure gradient than in the favorable pressure gradient channel. The results show also that the combined effects of rib roughness and adverse pressure gradient on the turbulent intensity statistics are significantly higher than when roughness and adverse pressure gradient are applied in isolation. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

PIV study of laminar wall jets of non-newtonian fluids / K. F. K. Adane in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 7 (Juillet 2010) 

Permalink

PIV study of turbulent flow in asymmetric converging and diverging channels / M. K. Shah in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 1 (Janvier 2008) 

Permalink