All Questions
Tagged with reversibility fluid-dynamics
10 questions
4
votes
2
answers
2k
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Why does entropy jump across a shockwave?
Using the Rankine-Hugoniot relations for a shockwave, one can show that entropy jumps across the shock, so that the entropy difference between upstream and downstream conditions is given by
$$s_2 - ...
- 2,659
3
votes
3
answers
1k
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From where does irreversibility arise in the Navier-Stokes momentum equation?
A form of the Navier-Stokes momentum equation can be written as: $$ \rho \left( \frac{\partial \mathbf{u}}{\partial t} + \mathbf{u} \cdot \nabla \mathbf{u} \right) = - \nabla \bar{p} + \mu \, \nabla^2 ...
- 669
2
votes
2
answers
433
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Reversibility of compressed air
Consider a gas hydro statically squeezed.
Now we slightly squeeze the gas, thus causing hydrostatic compression of the air. The slightly buoyant State 1 air then sinks to the bottom, shown in State 2 ...
- 1,772
1
vote
0
answers
155
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Entropy variation produced by a shock wave
I'm studying Compressible Fluid Mechanics through the book "Fluid Mechanics", 4 ed., by Frank White. I learnt that a shock wave is an irreversible process that occurs in the flow. Because of that, I ...
- 1,092
0
votes
1
answer
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If we replace dye in a Couette cell by little plastic balls, will rotating the cell show reversible behavior of the colloid?
In this great video, presented by R.I. Taylor, you can see that a dye introduced into a Couette cell shows reversible behavior if the walls of the two cylinders are turned a few times after which they ...
-1
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1
answer
2k
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Why is Stokes flow reversible?
Stokes flow is reversible because it is linear and instantaneous. Instantaneous means that is entirely the boundary conditions that define the movement at any given time.
What does the definition of "...
- 2,786
0
votes
1
answer
128
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Can we say higher entropy leads to better mixing in fluids?
We know irreversibilities always cause the entropy of the system to increase, but if we numerically find entropy generation due to heat transfer/fluid friction in a closed system, can we conclude ...
- 28
1
vote
1
answer
77
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Why does a soda bottle foam or froth when dropped? [duplicate]
Secondly, if I do drop a soda bottle how long do I have to keep it for it to return to its original state or condition, I.e. safe to open without froth spraying everywhere; or is there some rule of ...
- 409
7
votes
4
answers
9k
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Could you filter coffee back to being pure water?
Okay, so coffee filters remove solid matter from the beverage, whilst leaving the remaining coffee intact for caffeiney goodness.
But it's got me thinking. Is there a way we could filter the coffee ...
- 487
8
votes
2
answers
868
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Assumptions of thermodynamic & chemical equilibrium in fluid-dynamics
I am reading about the Euler equations of fluid dynamics from
Leveque's Numerical Methods for Conservation Laws. After introducing the mass, momentum and energy equations, some thermodynamic concepts ...
- 501