# Tagged Questions

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

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### Why does Bernoulli's equation only apply to flow along a streamline that is in viscid, incompressible, steady, irrotational?

I am learning about hydrofoil on this website. In a later video I watched, I learned that in the process of deriving Bernoulli's equation, $$constant=P/d+gh+1/2v^2$$ has to multiplied through by ...
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### Pipe in a flowing river problem

I'm working on a certain problem in fluid mechanics, which isn't really my strongest area. The problem is as follows: Curved pipe is partially submerged in a flowing river so that one end is pointing ...
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### How to estimate a drag of flow reversing cylinder?

I am assuming a turbulent flow and a full reversal of the flow (in the picture the arrows are at non-straight angle but please consider the skew as negligible). Assuming we are talking about ...
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### Maximum hole size to stop a fluid passing through a solid

In a previous question, the following is answered in a general sense: Assume I have a inverse cone which holds 200ml water. I am going to cut the tip of the cone to create a small hole. How to ...
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### Predict liquid film thickness outside a cylinder, under the influence of a) external gas flow and b) heating of the cylinder

I tried to post this question on Computational Science SE, but I was really unsure about the most appropriate SE site. The question didn't attract a lot of attention, and since Physics SE was my ...
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### How to derive end-correction value relationship for open-ended air columns?

According to Young and Freedman's Physics textbook, in open-ended air columns like some woodwind instruments, the position of the displacement antinode extends a tiny amount beyond the end of the ...
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### Application of Bernoulli's equation to siphon

I'm trying to understand how to use Bernoulli's equation in practice. So I will make an example of where is my confusion. I found this great explanation on Wikipedia about the siphon, but there is a ...
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### Analysis of a system consisting of a leaking tank of water

The departure point is this problem: A water tank on wheels is moving over an horizontal trail with negligible friction. There is a small opening in one of the walls, at a depth of $h$ below the ...
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### Smoothed particle hydrodynamics in cosmological N-body simulations

What is the role of smoothed particle hydrodynamics (SPH) in cosmological N-body simulations like the Millenium Run (performed with Gadget-2)?
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### Lorentz force for electrically conducting fluid flow in homogeneous magnetic field

I am mathematician and have paper which models situation when homogeneous magnetic field is applied to moving electrically conducting fluid. There is such Lorentz force formula on which all the work ...
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### Finding viscosity of a liquid [closed]

A ball bearing of diameter 10 mm is dropped into an oil of density 850 kgm–3. The ball bearing has a volume of 5.2 × 10^–7 m3 and density 7700 kgm–3. When the ball reaches terminal velocity ...
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I often read that when you have a deep cut on your arm, you should raise your arm to the point where the cut is above your heart. This should reduce the amount of blood loss because less blood reaches ...
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### How does the dissolution of salt affect the solution density?

Suppose you have a container of water as a solvent and you a certain amount of salt as a solute sitting at the bottom of the container that has yet to start dissolving. Supposing temperature and ...
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### How could water pour out from upside-down bottle, unless its pressure is smaller than atmosphere pressure?

Just a simple question : when we remove a stopper of an upside-down bottle, water flows out. But the pressure caused by the mass of water's column is usually smaller than atmosphere pressure unless we ...
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### What is the relative velocity term in drag and lift force in the following case?

When a stationary particle is introduced in a fluid moving with horizontal velocity $V_fx$, what is the relative velocity terms in the drag force ($F_D$) and lift force ($F_L$) equations. Am I correct ...
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### The demise of the Tacoma Narrows bridge was casused by aeroelastic flutter. But isn't that just a special case of resonance?

Much of the research I've done on the Tacoma Narrows bridge disaster of 1940 attribute the collapse of the bridge due to aeroelastic flutter - not strucural resonance. But isn't aeroelastic flutter ...
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### Equilibrium between two water tanks

I've been reading about hydrostatic theory, however I couldn't find a similar case/exercise about my basic problem. I have two water tanks (same size) filled with different water heights, and ...
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### Position based dynamics constraint scaling factor

Reading through Müller et al., Position Based Dynamics, 2007 I got lost when passing from equation (5) $$\Delta p = \frac{C(p)}{|\nabla_pC(p)|^2}\nabla_pC(p)$$ to equation (6) (and applying the ...
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### Why does stagnation pressure reduce across a normal shock?

I am seeking an explanation for this graph where the subscript "1" refers to the supersonic region and the subscript "2" refers to the subsonic region present beyond a normal shock. The static ...