Accepted Papers — Entropy
Manuscript ID: Entropy-2245
Type of Paper: Article
Title: Entropy Generation over an Inclined Backward-facing Step under Bleeding Conditions
Author: Seyyed A. Gandjalikhan Nassab * and Asad Bahrami and Rohollah Moosavi;
E-Mail: ganjali2000@yahoo.com (correspondent author)
Abstract: The current work investigates the entropy generation in a convection flow around an inclined backward facing step in a duct under bleeding conditions. The entropy generation is due to the heat transfer and viscous friction in a forced convection laminar flow. The set of governing equations containing the conservations of mass, momentum and energy are solved numerically to calculate the velocity and temperature profiles inside the flow domain. Because of the complex flow geometry and existence of inclined boundary in the physical plane, governing equation are solved numerically in the computational domain. Toward this end, conformal mapping is used to generate an orthogonal grid by means of the Schwarz-Christoffel transformation in which the transformation function is analytic. The governing equations are transformed into the computational domain and the discretized forms of these equations are obtained by the control volume method. In the numerical computations, the SIMPLE algorithm is used for the pressure-velocity coupling. Numerical expressions, in terms of the entropy generation number (Ns), Bejan number (Be) and Nusselt number (Nu) are derived in dimensionless forms using the velocity and temperature profiles. The effects of step inclined angle and bleed coefficient on the entropy generation number, Nusselt number, Bejan number and friction coefficient are presented for both suction and blowing processes.
Keywords: entropy generation; bleeding; inclined backward step; convection flow
Manuscript ID: Entropy-7132
Type of Paper: Article
Title: How the Nonextensivity Parameter Affects Energy Fluctuations
Author: Ezat Keshavarzi *, Abbas Helmi and Mohammad Kamalvand
E-Mails: keshavrz@cc.iut.ac.ir; a.helmi@ch.iut.ac.ir; kamalvand@gmail.com
Abstract: In this article, the effect of the nonextensivity parameter on the energy fluctuations of nonextensive systems has been studied in two different versions of the Tsallis statistical mechanics. While a general expression for the energy fluctuations in the second version has been reported,
the ideal gas and harmonic oscillator have been studied in the second and fourth versions of the Tsallis statistical mechanics. Our results in the fourth version show that the relative energy fluctuations are strongly affected by the nonextensivity parameter via the number of accessible states. In fact, in the case of subextensive systems, the nonextensivity parameter causes lower accessible states in comparison with the extensive systems and therefore, smaller relative energy fluctuations are expectable. But for super-extensive systems the relative energy fluctuations are larger than extensive systems because of the more accessible states available for a system. Our studies show that the un-normalized nature of second version causes very large relative energy fluctuations and in some cases limits its application.
Keywords: energy fluctuations; nonextensive systems; Harmonic oscillator; ideal gas; Tsallis statistical mechanics
PACS Codes: 05.20.-y