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

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207 views

Considerations and questions for a DIY heat pipe; how to choose a working fluid?

I plan to build a DIY heat pipe! For more info on what a heat pipe is, see Wikipedia. I would like to use it to cool a desktop graphics card I have. I am having trouble deciding how to choose the ...
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0answers
57 views

Nomenclature clarification concerning solitons

My experience with solitons is restricted to the classical setting, namely solutions to the quartic interaction $\phi^4$, the Sine-Gordon equation, and Korteweg–de Vries equations. I was explicit to ...
2
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1answer
100 views

Vortex shedding

So I was reading about vortex shedding, and got to know that it causes the building to resonate. Is there any way to use this resonance to generate electricity (maybe use quartz?) I am trying to make ...
1
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0answers
51 views

Collision of multiple fluid flows at a point [closed]

I would like to do an analysis when two or more fluid streams flowing from different direction with different velocity, meet at a point. What happen after the collision? Are there any related studies ...
0
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1answer
73 views

Why does the blade height goes on decreasing in a multi-stage axial flow compressor? [closed]

The axial compressors used in jet engines have their blade heights in decreasing order in the direction of the flow.
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1answer
65 views

Power of viscous friction on a falling sphere

I have derived a simple model of a rotameter using an homogeneous solid ball in a rigid cone where a fluid flows. I consider 4 forces: Weight, Buyancy, Viscous Friction and Drag. I have written my ...
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0answers
38 views

Vertical column of water for maintaining gas pressure in horizontal water tube?

I have an inverted T-Tube arrangement with the vertical tube of a height to add pressure to the continuously moving fluid of the horizontal tube. The purpose is to maintain dissolved gases in the ...
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0answers
48 views

Decay rate of overpressure for a nuclear blast (shockwave) over an urban area?

I have come across a very new idea for me concerning nuclear weapons effects, check this please. In brief, that person states that blast overpressure attenuates/decays by causing damage for each ...
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0answers
61 views

What is the magnitude of the sound that a Helmholtz Resonator attenuates?

I know that the shape of the Helmholtz Resonator, specifically its neck shape and the volume of its cavity, determine the resonance frequency of the resonator. Moreover, the resonance frequency is ...
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1answer
658 views

$\Delta T$, temperature units. How to use fahrenheit in this formula

To calculate the power in a fluid with a flow, the following formula is applied: $$P = \Delta T \rho c_p \times flow$$ $\Delta T$ can be entered as both Kelvin and Celsius. But what if I want to use ...
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1answer
97 views

What does the absence of hydrodynamic entrance effects do to the momentum conservation Equation?

I am trying to do a homework problem where we re-write the mass, momentum and energy conservation formulas for downward flow in a vertical pipe and it says "where all hydrodynamic entrance effects ...
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0answers
41 views

Is this explanation for the no-slip condition at a pipe wall correct?

The standard boundary condition for a fluid in contact with a surface is to enforce matching velocities at the interface. The explanation I was given is that contact forces between the wall and the ...
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0answers
68 views

Rotated glass with water

I think most of us know the experiment where you fill a glass with water, cover it and then turn upside down(holding the cover). You can read about it here I thought that it would be fun to do some ...
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2answers
138 views

Breaking ocean waves on other planets possible?

I have always wondered if there were an ocean on another planet with stronger or weaker gravity, would it be possible to have breaking waves?
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2answers
153 views

does the rate of change of height varies for different fluids?

I decided to experiment for the rate of flow of liquids (like water, oil, acid, etc) from a burette. I decided to use Torricelli's law $v=\sqrt{2gh}$. When experimenting, the time taken for a viscous ...
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4answers
14k views

Relation between pressure, velocity and area

In a nozzle, the exit velocity increases as per continuity equation $Av=const$ as given by Bernoulli equation (incompressible fluid). Pressure is inversely proportional to velocity, so we have lower ...
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1answer
96 views

gas pressure outside nozzle in vacuum

I'm currently trying to figure out the following in the simplest possible way: Say we have a nozzle in a vacuum environment. A gas of a certain pressure is emitted through the nozzle, which has a ...
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0answers
80 views

How does this help an aeroplane to fly? [duplicate]

I read it somewhere on the internet that wings of an aeroplane are designed in such a way, that they increase the velocity of air above the wings and so pressure above the plane becomes less than the ...
6
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1answer
175 views

Sailing against the wind. Is this a fair model?

I was ruminating the explanations about how boats can sail against the wind (or "into the wind"), and wondered if one could devise a simple mechanical model without hydrodynamics involved. Imagine a ...
2
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1answer
88 views

Non-determinitric flow of water stream on vertical porcelain surface

I noticed several times while washing my hands that accumulated water when starts streaming vertically does not flow vertically in straight line on vertical porcelain surface under the force of ...
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2answers
243 views

Efflux speed of ideal fluid dependent on diameter?

I have a cylinder full of water with diameter $D$ with a round opening on the bottom with diameter $d$. The water is friction-free and incompressible. Now I need a relationship for the efflux speed ...
0
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1answer
83 views

Blimp challenge. Doubts about volume at different heights [closed]

I want to design and build a small semi-rigid airship/dirigible. It will be controlled with RC so I will install motors, arduino, battery etc. Filled with helium. Weight of the equipment is about 2kg ...
2
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3answers
137 views

Explain Turbulence [closed]

I'm a high school student. I still don't understand what turbulence is. Please can you explain what it really is? This is what I think it is: rotating motion of water when a particle travels at a ...
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2answers
272 views

About how fast can a small fish swim before experiencing turbulent flow around its body? [closed]

About how fast can a small fish swim before experiencing turbulent flow around its body? An Engineering Problem! Please go through this question step by step. :D
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1answer
119 views

How to calculate fluid(oil / hydrocarbon) loss under pressure

I'm trying to calculate the amount of fluid that would flow through an area dependant on the amount of pressure that there is. I'd also like to know the rate at which it would flow. Essentially I ...
0
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1answer
127 views

Will Buoyant Force Change If The Container is Accelerated Up or Down?

If we have a fluid which is in a container that is accelerated, say, upward by $a$. Then, what will be the buoyant force on an object with volume $V$, Density of liquid, $\rho$? I believe it will be ...
3
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2answers
190 views

How does the pressurization in a house's water supply allow adjustable flowrates from a tap?

John Rennie's answer to this question got me thinking about the water supply in a house. I know that water supplies are normally operated at an over-pressure with respect to atmospheric pressure to ...
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2answers
235 views

Differences in the behaviour of pinching a garden hose and closing a tap

Let's say you have a garden hose connected to an ordinary water tap which is opened fully. If you pinch the end of the hose, water leaves the hose at a higher speed (and this can be useful while ...
1
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1answer
123 views

Smoothed Particle Hydrodynamics, Chemical Reactions and Stiffness [closed]

Dear people from stackexchange physics. I have been using SPH for quite a while to simulate free boundary flow, and just recently we tried to include some kind of (simple) chemical reaction in our ...
7
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1answer
657 views

Deriving shallow water equations from Euler's equations

I would like to derive the one-dimensional shallow water equations from Eulers's equations. This works perfectly for the conservation of mass. Especially the meaning of the longitudinal fluid ...
2
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1answer
77 views

Conservation of mass in fluid flow

When deriving the continuity equation in physics class for two immiscible fluids flowing in succession we used the principle of conservation of mass. My question is, shouldn't volume be conserved ...
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1answer
76 views

What is the physics concept in sponge filter

I really need help I want to ask what is the physics concept in Sponge Filter?
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1answer
106 views

Energy conservation at a the end of a hose pipe?

I am trying to figure out the energy balance at the end of a hose pipe with water pouring out. Applying Bernoulli's equation inside the pipe we have three energy terms: Kinetic energy, "pressure" ...
4
votes
1answer
200 views

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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0answers
55 views

Approximating density from pressure and flow

I want to get the density of a fluid going through a pipe. I can measure the flow and pressure with a flowmeter and the temperature using a thermometer. With this information, I want to calculate ...
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3answers
183 views

Spontaneous motion in a wind tunnel

Suppose that a hollow truncated cone is placed in a wind tunnel with a steady wind speed $V$. The cone is placed in such a way that it's base of area $A_1$ faces the wind (rather than the other side ...
0
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1answer
115 views

Does the space between molecules have no pressure?

In any living organism there exists are space between cells filled with interstitial fluid. Loss of this fluid into abnormal areas (3rd spacing) can cause relative to severe hypo-volemia. The fluid ...
4
votes
1answer
286 views

Why does a container with fluid make different sounds at different fluid levels?

Have you ever noticed that when you are filling a container with fluid. As it approaches the top, it makes a different sound? You can tell by listening when your about to reach the top. Why is this?
0
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1answer
399 views

How fast does the water travel down river when the discharge gates of a large dam are opened?

How fast does the water travel down river when the discharge gates of a large dam are opened? Can the discharge-wave travel downstream faster than the water? Is this likely to occur for a real river ...
2
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1answer
69 views

Air pressure in closed (circular) tube

I have learned that for fluids and gases $P_\text{total}=P_\text{dynamic} + P_\text{static}$. Suppose we have a closed circular tube in a form of ring filled with air under some pressure. In this ...
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3answers
203 views

pressure in fluid mechanics of incompressible liquid

Most liquids can be approximated to be incompressible, since the Mach-number is much smaller than 1. That means that the density variations are negligible and from the relation between pressure p and ...
0
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1answer
169 views

When to use ideal gas law in fluid mechanics?

The ideal gas law (aka the equation of state) is given by $$ p/\rho_N = k_BT, $$ where $\rho_N$ is number density. When am I allowed to use this to describe a fluid?
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3answers
1k views

How to freeze the Niagara waterfalls?

Here is a picture of the usual vigorous Niagara Falls (in the winter). Here is the picture of Niagara Falls frozen in 1933 (in the very cold winter). Here is the picture of Niagara Falls frozen in ...
5
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1answer
118 views

Transport theorem derivation question

I am trying to rigorously go through some fluid mechanics proofs and theorems. I am currently going through a proof related to the transport theorem and I am having trouble with a step. The steps in ...
9
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4answers
2k views

Festive physics: gold flake vodka

I have a bottle of vodka that has a load of gold flakes suspended in it. It has been sat still for over 24 hours and the flakes are all still suspended within the liquid: they have not risen to the ...
3
votes
1answer
120 views

Is it possible to use the parabolic shape of a rotating fluid to measure the angular frequency of the rotation of the Earth?

A fluid in a rotating bucket will take on a parabolic shape (for example of some simple derivations of this result see http://en.wikipedia.org/wiki/Bucket_argument). The assumptions that play into the ...
2
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1answer
131 views

Acceleration of particles in a pipe with variable cross section

I am currently making an exercise from Paterson,1983, IV.3.ii. It goes as follows Water flows steadily and incompressibly along a pipe whose area cross section $A(x)$ varies slowly with the ...
0
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1answer
128 views

Maximum liquid velocity in a siphon

According to wikipedia: Siphon, the velocity of liquid in a siphon is equal to $\sqrt{2gh}$, where h is the difference in level between the water surface and the opening of the siphon. But it also ...
0
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2answers
259 views

What is the aperture in the hydraulic analogy of Ohm's law

Note: My question is duplicate of Why doesn't water come out of tap/faucet at high pressure when I turn it on?. None of the answers given there explains how the continuity equation fits properly. ...
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1answer
73 views

shear and normal stresses

When we talk about shear stresses in a fluid, we find that the shear stress is given by $$\tau_{xy} = \mu(\partial_y u + \partial_x v) = \tau_{yx}$$ This relation we get when only looking at one side ...