# Questions tagged [fluid-dynamics]

The quantitative study of how fluids (gases and liquids) move.

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### How do I calculate the pressure $p_0$ on top of the water reservoir?

Can anyone help me with this question, I can't get the right answer :-) A water reservoir with depth D=200m, which is placed H=500m above on a mountain. A pipe is placed from the bottom of the ...
0answers
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### Why do we consider the viscous force to be tangential?

Is it that since it is a friction force, it needs to be tangential as other friction forces like kinetic friction and static friction forces are?
1answer
28 views

### What is the objective and reasoning of no slip condition? [duplicate]

My Professor used to say that there are two aspects to consider when making an assumption: The purpose of making the assumption and the justification as to why it's scientifically valid. I would like ...
1answer
22 views

### Pressure in Bernoulli principle

In Bernoulli principle we say that as velocity increases the pressure of fluid decreases but it contradicts kinetic theory of gas which says that as velocity increase-pressure increases. And this ...
0answers
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### What percentage reduction in water surface area does induced supercavitation begin to limit propeller thrust? [on hold]

Does a surface drive propeller reduce its power running through supercavitating bubbles?
0answers
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### Pipe pressure drop question [on hold]

Water at $20^\circ$C is flowing at $0.1$ cm s$^{-1}$ in a $5$ cm diameter pipe. If the pipe has an equivalent length of 10 m what pressure drop would be expected? Comment on any assumptions made. Is ...
0answers
9 views

### What is the lowest-energy configuration of a perfect fluid of constant angular momentum under gravity?

What is the lowest-energy stable configuration of a perfect (homogeneous dense incompressible inviscid) non-oscillatory fluid of constant mass and angular momentum under Newtonian self-gravity? For ...
0answers
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0answers
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### Analytical solution to damped harmonic oscillator - Fokker-Planck equation

In the paper "Numerical solution of two dimensional Fokker-Planck equations" (available at: https://doi.org/10.1016/S0096-3003(97)10161-8), the authors quote an analytical solution to the damped ...
1answer
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1answer
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### Time taken by bubble to come to surface

Does air bubble take same time to emerge from shallow water and deep water? I think the acceleration due to buoyancy will be the cause.
3answers
78 views

### Why does surface area not matter when calculating pressure

I can not understand why the surface area that atmospheric pressure is acting upon does not matter when calculating pressure. For example look at the water jug below with 2 openings, one small and ...