Title: Second law analysis of Giesekus viscoelastic fluid for axial annular flow

Authors: Mehdi Moayed Mohseni; Fariborz Rashidi

Addresses: Chemical Engineering Department, Amirkabir University of Technology, P.O. Box 15875-4413, No. 472, Hafez Ave., Tehran, Iran ' Chemical Engineering Department, Amirkabir University of Technology, P.O. Box 15875-4413, No. 472, Hafez Ave., Tehran, Iran

Abstract: The first and second laws of thermodynamics are analysed for viscoelastic fluid obeying Giesekus constitutive equation in concentric annulus under steady, laminar flow with both thermal and hydrodynamic fully developed conditions. Two types of boundary conditions are employed in this study. (a) Uniform heat flux is imposed at outer cylinder and insulated condition is considered for inner cylinder. (b) Both cylinders are kept at different constant temperatures. Governing equations in cylindrical coordinate system are simplified and then solved to obtain analytical expressions for temperature profile (Θ), entropy generation number (NS) and Bejan number (Be). The effect of group parameter (Br/Ω), Brinkman number (Br), Deborah number (De) and mobility factor (α) are discussed. Results indicate that entropy generation decreases with increasing De and α while an increase in Br and Br/Ω cause increase in the entropy generation.

Keywords: entropy generation; Bejan number; concentric annulus; Giesekus constitutive equations; analytical solutions; second law; thermodynamics; viscoelastic fluids; axial annular flow; heat flux; temperature profile.

DOI: 10.1504/IJEX.2015.069117

International Journal of Exergy, 2015 Vol.16 No.4, pp.404 - 429

Received: 10 Feb 2014
Accepted: 21 Apr 2014
Published online: 28 Apr 2015 *

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