Connection between entropy and total pressure

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SUMMARY

The discussion centers on the relationship between entropy and total (stagnation) pressure, specifically how an increase in entropy correlates with a decrease in total pressure due to shear stress. The participant highlights that shear stress contributes to entropy production in the entropy transport equation and affects kinetic and internal energy transport. They reference Bernoulli's equation, noting that total pressure comprises static and dynamic pressure, with dynamic pressure linked to kinetic energy. The conclusion drawn is that friction reduces total pressure while simultaneously increasing entropy, questioning the existence of a direct equation connecting these properties.

PREREQUISITES
  • Understanding of entropy transport equations
  • Familiarity with Bernoulli's equation
  • Knowledge of shear stress and its effects on energy
  • Basic principles of thermodynamics
NEXT STEPS
  • Research the entropy transport equation in detail
  • Study the implications of shear stress on kinetic and internal energy
  • Examine advanced applications of Bernoulli's equation in fluid dynamics
  • Explore the mathematical formulation of entropy generation rates
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Students and professionals in thermodynamics, fluid dynamics engineers, and researchers interested in the interplay between entropy and pressure in physical systems.

obad
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Hi guys,

I'm struggling to understand why an increase of entropy is directly linked with a decrease of total (stagnation) pressure. I have an idea, but I'm not sure if this is right.

My understanding of the problem is as follows:
Shear stress (friction) is a part of the entropy production term of the entropy transport equation. So when looking at this transport equation the role of friction is clear to me.
Furthermore shear stress is also contained in the source term of the kinetic energy and internal energy transport equation. Where friction converts kinetic energy into internal energy.
Now when looking at Bernoulli's equation, total pressure is a combination of the static and the dynamic pressure. Dynamic pressure is related to kinetic energy.

So could I say that friction simply reduces total pressure and increases entropy at the same time and there is actually no equation that describes a direct connection between these properties?

Cheers!
 
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From your understanding, what is the equation (or equations) for the rate of entropy generation per unit volume?
 

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