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Article

A Numerical Study on Entropy Generation in Two-Dimensional Rayleigh-Bénard Convection at Different Prandtl Number

by 1,*,†, 2,*,† and 2
1
Faculty of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China
2
Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai University, Shanghai 200072, China
*
Authors to whom correspondence should be addressed.
These authors contributed equally to this work.
Entropy 2017, 19(9), 443; https://doi.org/10.3390/e19090443
Received: 2 July 2017 / Revised: 16 August 2017 / Accepted: 21 August 2017 / Published: 30 August 2017
(This article belongs to the Special Issue Entropy in Computational Fluid Dynamics)
Entropy generation in two-dimensional Rayleigh-Bénard convection at different Prandtl number (Pr) are investigated in the present paper by using the lattice Boltzmann Method. The major concern of the present paper is to explore the effects of Pr on the detailed information of local distributions of entropy generation in virtue of frictional and heat transfer irreversibility and the overall entropy generation in the whole flow field. The results of this work indicate that the significant viscous entropy generation rates (Su) gradually expand to bulk contributions of cavity with the increase of Pr, thermal entropy generation rates (Sθ) and total entropy generation rates (S) mainly concentrate in the steepest temperature gradient, the entropy generation in the flow is dominated by heat transfer irreversibility and for the same Rayleigh number, the amplitudes of Su, Sθ and S decrease with increasing Pr. It is found that that the amplitudes of the horizontally averaged viscous entropy generation rates, thermal entropy generation rates and total entropy generation rates decrease with increasing Pr. The probability density functions of Su, Sθ and S also indicate that a much thinner tail while the tails for large entropy generation values seem to fit the log-normal curve well with increasing Pr. The distribution and the departure from log-normality become robust with decreasing Pr. View Full-Text
Keywords: entropy; Prandtl number; Rayleigh number; thermal; lattice Boltzmann method entropy; Prandtl number; Rayleigh number; thermal; lattice Boltzmann method
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MDPI and ACS Style

Wei, Y.; Wang, Z.; Qian, Y. A Numerical Study on Entropy Generation in Two-Dimensional Rayleigh-Bénard Convection at Different Prandtl Number. Entropy 2017, 19, 443. https://doi.org/10.3390/e19090443

AMA Style

Wei Y, Wang Z, Qian Y. A Numerical Study on Entropy Generation in Two-Dimensional Rayleigh-Bénard Convection at Different Prandtl Number. Entropy. 2017; 19(9):443. https://doi.org/10.3390/e19090443

Chicago/Turabian Style

Wei, Yikun, Zhengdao Wang, and Yuehong Qian. 2017. "A Numerical Study on Entropy Generation in Two-Dimensional Rayleigh-Bénard Convection at Different Prandtl Number" Entropy 19, no. 9: 443. https://doi.org/10.3390/e19090443

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