The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform

Sudhir K. Sastry - One of the best experts on this subject based on the ideXlab platform.

Hans J. Herrmann - One of the best experts on this subject based on the ideXlab platform.

  • Transition in the Equilibrium Distribution function of relativistic particles.
    Scientific Reports, 2012
    Co-Authors: Miller Mendoza, Nuno A. M. Araújo, Sauro Succi, Hans J. Herrmann
    Abstract:

    We analyze a transition from single peaked to bimodal velocity Distribution in a relativistic fluid under increasing temperature, in contrast with a non-relativistic gas, where only a monotonic broadening of the bell-shaped Distribution is observed. Such transition results from the interplay between the raise in thermal energy and the constraint of maximum velocity imposed by the speed of light. We study the Bose-Einstein, the Fermi-Dirac, and the Maxwell-Juttner Distributions, and show that they all exhibit the same qualitative behavior. We characterize the nature of the transition in the framework of critical phenomena and show that it is either continuous or discontinuous, depending on the group velocity. We analyze the transition in one, two, and three dimensions, with special emphasis on twodimensions, for which a possible experiment in graphene, based on the measurement of the Johnson-Nyquist noise, is proposed.

Peter V Coveney - One of the best experts on this subject based on the ideXlab platform.

  • inverse chapman enskog derivation of the thermohydrodynamic lattice bgk model for the ideal gas
    International Journal of Modern Physics C, 1998
    Co-Authors: Bruce M. Boghosian, Peter V Coveney
    Abstract:

    A thermohydrodynamic lattice-BGK model for the ideal gas was derived by Alexander et al. in 1993, and generalized by McNamara et al. in the same year. In these works, particular forms for the Equilibrium Distribution function and the transport coefficients were posited and shown to work, thereby establishing the sufficiency of the model. In this paper, we rederive the model from a minimal set of assumptions, and thereby show that the forms assumed for the shear and bulk viscosities are also necessary, but that the form assumed for the thermal conductivity is not. We derive the most general form allowable for the thermal conductivity, and the concomitant generalization of the Equilibrium Distribution. In this way, we show that it is possible to achieve variable (albeit density-dependent) Prandtl number even within a single-relaxation-time lattice-BGK model. We accomplish this by demanding analyticity of the third moments and traces of the fourth moments of the Equilibrium Distribution function. The method of derivation demonstrates that certain undesirable features of the model — such as the unphysical dependence of the viscosity coefficients on temperature — cannot be corrected within the scope of lattice-BGK models with constant relaxation time.

  • Inverse Chapman–Enskog Derivation of the Thermohydrodynamic Lattice-BGK Model for the Ideal Gas
    International Journal of Modern Physics C, 1998
    Co-Authors: Bruce M. Boghosian, Peter V Coveney
    Abstract:

    A thermohydrodynamic lattice-BGK model for the ideal gas was derived by Alexander et al. in 1993, and generalized by McNamara et al. in the same year. In these works, particular forms for the Equilibrium Distribution function and the transport coefficients were posited and shown to work, thereby establishing the sufficiency of the model. In this paper, we rederive the model from a minimal set of assumptions, and thereby show that the forms assumed for the shear and bulk viscosities are also necessary, but that the form assumed for the thermal conductivity is not. We derive the most general form allowable for the thermal conductivity, and the concomitant generalization of the Equilibrium Distribution. In this way, we show that it is possible to achieve variable (albeit density-dependent) Prandtl number even within a single-relaxation-time lattice-BGK model. We accomplish this by demanding analyticity of the third moments and traces of the fourth moments of the Equilibrium Distribution function. The method of derivation demonstrates that certain undesirable features of the model — such as the unphysical dependence of the viscosity coefficients on temperature — cannot be corrected within the scope of lattice-BGK models with constant relaxation time.

Helmuth Möhwald - One of the best experts on this subject based on the ideXlab platform.

  • Equilibrium Distribution of permeants in polyelectrolyte microcapsules filled with negatively charged polyelectrolyte: the influence of ionic strength and solvent polarity.
    The journal of physical chemistry. B, 2006
    Co-Authors: Weijun Tong, Haiqing Song, Changyou Gao, Helmuth Möhwald
    Abstract:

    The effects of ionic strength and solvent polarity on the Equilibrium Distribution of fluorescein (FL) and FITC−dextran between the interior of polyelectrolyte multilayer microcapsules filled with negatively charged strong polyelectrolyte and the bulk solution were systematically investigated. A negatively charged strong polyelectrolyte, poly(styrene sulfonate) (PSS), used for CaCO3 core fabrication, was entrapped inside the capsules. Due to the semipermeability of the capsule wall, a Donnan Equilibrium between the inner solution within the capsules and the bulk solution was created. The Equilibrium Distribution of the negatively charged permeants was investigated by means of confocal laser scanning microscopy as a function of ionic strength and solvent polarity. The Equilibrium Distribution of the negatively charged permeants could be tuned by increasing the bulk ionic strength to decrease the Donnan potential. Decreasing the solvent polarity also could enhance the permeation of FL, which induces a sudde...

Sanjay Sarang - One of the best experts on this subject based on the ideXlab platform.