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A Stepanian - One of the best experts on this subject based on the ideXlab platform.

  • the djorgovski gurzadyan dark Energy Integral Equation and the hubble diagram
    Astronomy and Astrophysics, 2020
    Co-Authors: H G Khachatryan, A Stepanian
    Abstract:

    We consider the observational aspects of the value of dark Energy density from quantum vacuum fluctuations based initially on the Gurzadyan–Xue model. We reduce the Djorgovski–Gurzadyan Integral Equation to a differential Equation for the co-moving horizon and then, by means of the obtained explicit form for the luminosity distance, we construct the Hubble diagram for two classes of observational samples. For supernova and gamma-ray burst data we show that this approach provides viable predictions for distances up to z  ≃ 9, quantitatively at least as good as those provided by the Λ cold dark matter model. The Hubble parameter dependence H (z ) of the two models also reveals mutual crossing at z  = 0.4018, the interpretation of which is less evident.

  • the djorgovski gurzadyan dark Energy Integral Equation and the hubble diagram
    arXiv: Cosmology and Nongalactic Astrophysics, 2020
    Co-Authors: H G Khachatryan, A Stepanian
    Abstract:

    We consider the observational aspects of the value of dark Energy density from quantum vacuum fluctuations based initially on the Gurzadyan-Xue model. We reduce the Djorgovski-Gurzadyan Integral Equation to a differential Equation for the co-moving horizon and then, by means of the obtained explicit form for the luminosity distance, we construct the Hubble diagram for two classes of observational samples. For supernova and gamma-ray burst data we show that this approach provides viable predictions for distances up to $z \simeq 9$, quantitatively at least as good as those provided by the lambda cold dark matter ($\Lambda$CDM) model. The Hubble parameter dependence $H(z)$ of the two models also reveals mutual crossing at $z=0.4018$, the interpretation of which is less evident.

H G Khachatryan - One of the best experts on this subject based on the ideXlab platform.

  • the djorgovski gurzadyan dark Energy Integral Equation and the hubble diagram
    Astronomy and Astrophysics, 2020
    Co-Authors: H G Khachatryan, A Stepanian
    Abstract:

    We consider the observational aspects of the value of dark Energy density from quantum vacuum fluctuations based initially on the Gurzadyan–Xue model. We reduce the Djorgovski–Gurzadyan Integral Equation to a differential Equation for the co-moving horizon and then, by means of the obtained explicit form for the luminosity distance, we construct the Hubble diagram for two classes of observational samples. For supernova and gamma-ray burst data we show that this approach provides viable predictions for distances up to z  ≃ 9, quantitatively at least as good as those provided by the Λ cold dark matter model. The Hubble parameter dependence H (z ) of the two models also reveals mutual crossing at z  = 0.4018, the interpretation of which is less evident.

  • the djorgovski gurzadyan dark Energy Integral Equation and the hubble diagram
    arXiv: Cosmology and Nongalactic Astrophysics, 2020
    Co-Authors: H G Khachatryan, A Stepanian
    Abstract:

    We consider the observational aspects of the value of dark Energy density from quantum vacuum fluctuations based initially on the Gurzadyan-Xue model. We reduce the Djorgovski-Gurzadyan Integral Equation to a differential Equation for the co-moving horizon and then, by means of the obtained explicit form for the luminosity distance, we construct the Hubble diagram for two classes of observational samples. For supernova and gamma-ray burst data we show that this approach provides viable predictions for distances up to $z \simeq 9$, quantitatively at least as good as those provided by the lambda cold dark matter ($\Lambda$CDM) model. The Hubble parameter dependence $H(z)$ of the two models also reveals mutual crossing at $z=0.4018$, the interpretation of which is less evident.

M M Yovanovich - One of the best experts on this subject based on the ideXlab platform.

  • FLUID FLOW AND HEAT TRANSFER IN POWER-LAW FLUIDS ACROSS CIRCULAR CYLINDERS- ANALYTICAL STUDY
    2014
    Co-Authors: W A Khan, Richard J. Culham, M M Yovanovich
    Abstract:

    An Integral approach of the boundary layer analysis is em-ployed for the modeling of fluid flow around and heat transfer from infinite circular cylinders in power-law fluids. The Von Karman-Pohlhausen method is used to solve the momentum inte-gral Equation whereas the Energy Integral Equation is solved for both isothermal and isoflux boundary conditions. A fourth-order velocity profile in the hydrodynamic boundary layer and a third-order temperature profile in the thermal boundary layer are used to solve both Integral Equations. Closed form expressions are obtained for the drag and heat transfer coefficients that can be used for a wide range of the power-law index, and generalized Reynolds and Prandtl numbers. It is found that pseudoplastic fluids offer less skin friction and higher heat transfer coefficients than dilatant fluids. As a result, the drag coefficients decreas

  • fluid flow and heat transfer in power law fluids across circular cylinders analytical study
    Journal of Heat Transfer-transactions of The Asme, 2006
    Co-Authors: W A Khan, J R Culham, M M Yovanovich
    Abstract:

    An Integral approach of the boundary layer analysis is employed for the modeling of fluid flow around and heat transfer from infinite circular cylinders in power-law fluids. The Von Karman-Pohlhausen method is used to solve the momentum Integral Equation whereas the Energy Integral Equation is solved for both isothermal and isoflux boundary conditions. A fourth-order velocity profile in the hydrodynamic boundary layer and a third-order temperature profile in the thermal boundary layer are used to solve both Integral Equations. Closed form expressions are obtained for the drag and heat transfer coefficients that can be used for a wide range of the power-law index, and generalized Reynolds and Prandtl numbers. It is found that pseudoplastic fluids offer less skin friction and higher heat transfer coefficients than dilatant fluids. As a result, the drag coefficients decrease and the heat transfer increases with the decrease in power-law index. Comparison of the analytical models with available experimental/numerical data proves the applicability of the Integral approach for power-law fluids. DOI: 10.1115/1.2241747

W A Khan - One of the best experts on this subject based on the ideXlab platform.

  • FLUID FLOW AND HEAT TRANSFER IN POWER-LAW FLUIDS ACROSS CIRCULAR CYLINDERS- ANALYTICAL STUDY
    2014
    Co-Authors: W A Khan, Richard J. Culham, M M Yovanovich
    Abstract:

    An Integral approach of the boundary layer analysis is em-ployed for the modeling of fluid flow around and heat transfer from infinite circular cylinders in power-law fluids. The Von Karman-Pohlhausen method is used to solve the momentum inte-gral Equation whereas the Energy Integral Equation is solved for both isothermal and isoflux boundary conditions. A fourth-order velocity profile in the hydrodynamic boundary layer and a third-order temperature profile in the thermal boundary layer are used to solve both Integral Equations. Closed form expressions are obtained for the drag and heat transfer coefficients that can be used for a wide range of the power-law index, and generalized Reynolds and Prandtl numbers. It is found that pseudoplastic fluids offer less skin friction and higher heat transfer coefficients than dilatant fluids. As a result, the drag coefficients decreas

  • fluid flow and heat transfer in power law fluids across circular cylinders analytical study
    Journal of Heat Transfer-transactions of The Asme, 2006
    Co-Authors: W A Khan, J R Culham, M M Yovanovich
    Abstract:

    An Integral approach of the boundary layer analysis is employed for the modeling of fluid flow around and heat transfer from infinite circular cylinders in power-law fluids. The Von Karman-Pohlhausen method is used to solve the momentum Integral Equation whereas the Energy Integral Equation is solved for both isothermal and isoflux boundary conditions. A fourth-order velocity profile in the hydrodynamic boundary layer and a third-order temperature profile in the thermal boundary layer are used to solve both Integral Equations. Closed form expressions are obtained for the drag and heat transfer coefficients that can be used for a wide range of the power-law index, and generalized Reynolds and Prandtl numbers. It is found that pseudoplastic fluids offer less skin friction and higher heat transfer coefficients than dilatant fluids. As a result, the drag coefficients decrease and the heat transfer increases with the decrease in power-law index. Comparison of the analytical models with available experimental/numerical data proves the applicability of the Integral approach for power-law fluids. DOI: 10.1115/1.2241747

Stepanian A. - One of the best experts on this subject based on the ideXlab platform.

  • On the Djorgovski-Gurzadyan dark Energy Integral Equation and the Hubble diagram
    'EDP Sciences', 2020
    Co-Authors: Khachatryan H. G., Stepanian A.
    Abstract:

    We consider the observational aspects of the value of dark Energy density from quantum vacuum fluctuations based initially on the Gurzadyan-Xue model. We reduce Djorgovski-Gurzadyan Integral Equation to a differential Equation for the co-moving horizon and then, by means of the obtained explicit form for the luminosity distance, we construct the Hubble diagram for two classes of observational samples. For supernova and gamma-ray burst data we show that this approach provides viable predictions for distances up to $z \simeq 9$, quantitatively at least as good as the $\Lambda$CDM model does. The Hubble parameter dependence $H(z)$ of both models also reveals mutual crossing at $z=0.4018$, the interpretation of which seems less evident.Comment: A&A Lett. (in press), 4 pages, 5 figure