The generalized engineering Bernoulli equation (GEBE) and the first and second laws of thermodynamics for viscoelastic fluids
作者:
Gianni Astarita,
Michael E. Mackay,
期刊:
Journal of Rheology
(AIP Available online 1996)
卷期:
Volume 40,
issue 3
页码: 335-346
ISSN:0148-6055
年代: 1996
DOI:10.1122/1.550746
出版商: The Society of Rheology
关键词: Bernoulli equation;Engineering Bernoulli equation;Dissipation;Thermodynamics;BERNOULLI LAW;ENERGY LOSSES;ENERGY BALANCE;THERMODYNAMICS;ENTROPY;EQUATIONS OF MOTION;INCOMPRESSIBLE FLOW;STEADY FLOW
数据来源: AIP
摘要:
In this work we thoroughly explore the meanings of dissipation (sometimes referred to as viscous dissipation) and stress power. To do this we utilize the Cauchy momentum equations and the first and second laws of thermodynamics. First, the generalized engineering Bernoulli equation (GEBE) is derived from the Cauchy momentum equations and it is clearly shown to have nothing to do with a balance of energy. Next, the first law of thermodynamics or energy balance is discussed and a combined equation by subtracting the two is derived which we refer to as the mechanoenergy balance (sometimes referred to as the ‘‘equation of thermal energy’’). The fact that a difference exists further reinforces that the GEBE is not related to a balance of energy. Finally, the second law of thermodynamics is presented and the concept of dissipation introduced. An example is presented to demonstrate the utility of these equations which will hopefully eliminate some confusion in the literature.
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