Documents disponibles écrits par cet auteur

Buoyancy driven heat transfer of nanofluids in a tilted enclosure / Kamil Kahveci in Journal of heat transfer, Vol. 132 N° 6 (Juin 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 6 (Juin 2010) . - pp. [062501-1/12] Titre : Buoyancy driven heat transfer of nanofluids in a tilted enclosure Type de document : texte imprimé Auteurs : Kamil Kahveci, Auteur Article en page(s) : pp. [062501-1/12] Note générale : Physique Langues : Anglais (eng) Mots-clés : Naturel  convection  Nanofluid  Enclosure  PDQ  Vorticity  Stream  function Index. décimale : 536 Chaleur. Thermodynamique Résumé : Buoyancy driven heat transfer of water-based nanofluids in a differentially heated, tilted enclosure is investigated in this study. The governing equations (obtained with the Boussinesq approximation) are solved using the polynomial differential quadrature method for an inclination angle ranging from 0 deg to 90 deg, two different ratios of the nanolayer thickness to the original particle radius (0.02 and 0.1), a solid volume fraction ranging from 0% to 20%, and a Rayleigh number varying from 104 to 106. Five types of nanoparticles, Cu, Ag, CuO, Al2O3, and TiO2 are taken into consideration. The results show that the average heat transfer rate from highest to lowest is for Ag, Cu, CuO, Al2O3, and TiO2. The results also show that for the particle radius generally used in practice (beta=0.1 or beta=0.02), the average heat transfer rate increases to 44% for Ra=104, to 53% for Ra=105, and to 54% for Ra=106 if the special case of theta=90 deg, which also produces the minimum heat transfer rates, is not taken into consideration. As for theta=90 deg, the heat transfer enhancement reaches 21% for Ra=104, 44% for Ra=105, and 138% for Ra=106. The average heat transfer rate shows an increasing trend with an increasing inclination angle, and a peak value is detected. Beyond the peak point, the foregoing trend reverses and the average heat transfer rate decreases with a further increase in the inclination angle. Maximum heat transfer takes place at theta=45 deg for Ra=104 and at theta=30 deg for Ra=105 and 106. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Buoyancy driven heat transfer of nanofluids in a tilted enclosure [texte imprimé] / Kamil Kahveci, Auteur . - pp. [062501-1/12]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 6 (Juin 2010) . - pp. [062501-1/12] Mots-clés : Naturel  convection  Nanofluid  Enclosure  PDQ  Vorticity  Stream  function Index. décimale : 536 Chaleur. Thermodynamique Résumé : Buoyancy driven heat transfer of water-based nanofluids in a differentially heated, tilted enclosure is investigated in this study. The governing equations (obtained with the Boussinesq approximation) are solved using the polynomial differential quadrature method for an inclination angle ranging from 0 deg to 90 deg, two different ratios of the nanolayer thickness to the original particle radius (0.02 and 0.1), a solid volume fraction ranging from 0% to 20%, and a Rayleigh number varying from 104 to 106. Five types of nanoparticles, Cu, Ag, CuO, Al2O3, and TiO2 are taken into consideration. The results show that the average heat transfer rate from highest to lowest is for Ag, Cu, CuO, Al2O3, and TiO2. The results also show that for the particle radius generally used in practice (beta=0.1 or beta=0.02), the average heat transfer rate increases to 44% for Ra=104, to 53% for Ra=105, and to 54% for Ra=106 if the special case of theta=90 deg, which also produces the minimum heat transfer rates, is not taken into consideration. As for theta=90 deg, the heat transfer enhancement reaches 21% for Ra=104, 44% for Ra=105, and 138% for Ra=106. The average heat transfer rate shows an increasing trend with an increasing inclination angle, and a peak value is detected. Beyond the peak point, the foregoing trend reverses and the average heat transfer rate decreases with a further increase in the inclination angle. Maximum heat transfer takes place at theta=45 deg for Ra=104 and at theta=30 deg for Ra=105 and 106. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

A differential quadrature solution of MHD natural convection in an inclined enclosure with a partition / Kamil Kahveci in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 2 (Fevrier 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 2 (Fevrier 2008) . - 14 p. Titre : A differential quadrature solution of MHD natural convection in an inclined enclosure with a partition Type de document : texte imprimé Auteurs : Kamil Kahveci, Auteur ; Semiha Öztuna, Auteur Année de publication : 2009 Article en page(s) : 14 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Magnetic  fields;  interior  walls;  Rayleigh  number;  flow  (dynamics);  heat  transfer;  vorticity;  natural  convection;  equations;  Prandtl  number;  fluids;  convection;  boundary  layers;  corners  (structural  elements) Résumé : Magnetohydrodynamics natural convection in an inclined enclosure with a partition is studied numerically using a differential quadrature method. Governing equations for the fluid flow and heat transfer are solved for the Rayleigh number varying from 104 to 106, the Prandtl numbers (0.1, 1, and 10), four different Hartmann numbers (0, 25, 50, and 100), the inclination angle ranging from 0degto90deg, and the magnetic field with the x and y directions. The results show that the convective flow weakens considerably with increasing magnetic field strength, and the x-directional magnetic field is more effective in reducing the convection intensity. As the inclination angle increases, multicellular flows begin to develop on both sides of the enclosure for higher values of the Hartmann number if the enclosure is under the x-directional magnetic field. The vorticity generation intensity increases with increase of Rayleigh number. On the other hand, increasing Hartmann number has a negative effect on vorticity generation. With an increase in the inclination angle, the intensity of vorticity generation is observed to shift to top left corners and bottom right corners. Vorticity generation loops in each region of enclosure form due to multicelluar flow for an x-directional magnetic field when the inclination angle is increased further. In addition, depending on the boundary layer developed, the vorticity value on the hot wall increases first sharply with increasing y and then begins to decrease gradually. For the high Rayleigh numbers, the average Nusselt number shows an increasing trend as the inclination angle increases and a peak value is detected. Beyond the peak point, the foregoing trend reverses to decrease with the further increase of the inclination angle. The results also show that the Prandtl number has only a marginal effect on the flow and heat transfer. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] A differential quadrature solution of MHD natural convection in an inclined enclosure with a partition [texte imprimé] / Kamil Kahveci, Auteur ; Semiha Öztuna, Auteur . - 2009 . - 14 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 2 (Fevrier 2008) . - 14 p. Mots-clés : Magnetic  fields;  interior  walls;  Rayleigh  number;  flow  (dynamics);  heat  transfer;  vorticity;  natural  convection;  equations;  Prandtl  number;  fluids;  convection;  boundary  layers;  corners  (structural  elements) Résumé : Magnetohydrodynamics natural convection in an inclined enclosure with a partition is studied numerically using a differential quadrature method. Governing equations for the fluid flow and heat transfer are solved for the Rayleigh number varying from 104 to 106, the Prandtl numbers (0.1, 1, and 10), four different Hartmann numbers (0, 25, 50, and 100), the inclination angle ranging from 0degto90deg, and the magnetic field with the x and y directions. The results show that the convective flow weakens considerably with increasing magnetic field strength, and the x-directional magnetic field is more effective in reducing the convection intensity. As the inclination angle increases, multicellular flows begin to develop on both sides of the enclosure for higher values of the Hartmann number if the enclosure is under the x-directional magnetic field. The vorticity generation intensity increases with increase of Rayleigh number. On the other hand, increasing Hartmann number has a negative effect on vorticity generation. With an increase in the inclination angle, the intensity of vorticity generation is observed to shift to top left corners and bottom right corners. Vorticity generation loops in each region of enclosure form due to multicelluar flow for an x-directional magnetic field when the inclination angle is increased further. In addition, depending on the boundary layer developed, the vorticity value on the hot wall increases first sharply with increasing y and then begins to decrease gradually. For the high Rayleigh numbers, the average Nusselt number shows an increasing trend as the inclination angle increases and a peak value is detected. Beyond the peak point, the foregoing trend reverses to decrease with the further increase of the inclination angle. The results also show that the Prandtl number has only a marginal effect on the flow and heat transfer. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]