Questions tagged [fluid-dynamics]
The quantitative study of how fluids (gases and liquids) move.
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Gravity duals to Navier Stokes and interpretation of non linear contributions
I have been reading the paper The Incompressible Non-Relativistic Navier-Stokes Equation from Gravity. In it they state,
"An instability, if it occurs, must necessarily break a symmetry ...
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Can wind blowing on smooth water create speckle interference patterns?
On a calm smooth lake, or even a large rain puddle, I've seen transient rough patches on the surface suddenly appear and disappear, and sometimes move across the water some distance before ...
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Where can I check a solution to 3D Navier Stokes?
A few years ago I developed a solution to the Navier-Stokes equations and as of yet have not been able to locate a similar version of the solution. I would like to know if anyone has seen a solution ...
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Swimming and forces
I was told that the total integral of the stress over the surface of a swimmer (i.e. the total force exerted by the swimmer on the fluid) always vanishes, because there are no external forces applied ...
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Lamb-Chaplygin dipole
There is an interesting issue of hydrodynamics: whirlpools.
I want to learn about the Lamb-Chaplygin dipole.
Lamb-Chaplygin dipole corresponds to a steady solution of the two dimensional Euler ...
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The viscous force between the layers of liquid is same, then why there is variation in the velocities of its layers?
I have learned in my textbook that when the liquid flows the bottom layer of the liquid never moves because of friction, but the upper layers move with increasing velocities how it is possible if the ...
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Sound level of organ pipe driven by helium
The sound pressure level of an organ pipe is a function of the gas flow rate delivered to the pipe. Source
Would the sound level of an organ pipe driven by helium be lower than that of a pipe driven ...
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How do I calculate the energy balance of a trompe?
I was quite fascinated by the concept of an ancient type of air compressor, called a trompe. It entrains air bubbles into a falling stream of water via the Venturi effect, and extracts the air at a ...
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Stat mech explanation for separation of one liquid from another in gravity?
If one mixes two distinct ideal gases above the Earth's surface, one with a higher molecular mass than the other, then at equilibrium, their number density gradients will be such that at low heights, ...
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Is it wrong to associate non-isotropic flow high with Reynolds-Number and is there a better metric?
IT is often stated the flow with high Re is not isotropic, meaning there is no uniform or dominant direction of the flow. But this seems wrong to me - -while there's certainly cases where no dominant ...
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Disregarding drag force that affects pop-up lightweight ball
Is it possible to disregard drag force of water with no viscosity that affects lightweight pop-up ball (its weight is assumed to be zero)? There is a discussion, on which I consider that although ...
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How much effect does the Bernoulli effect have on lift?
I understand that the Bernoulli effect is a flawed explanation for the cause of lift, and does not cause much at all, but how much?
Is there any experimental data on the force caused by the ...
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Why does smoke go inside the car if the back door is open?
Inspired by another question I wanted to ask about phenomenon that I've experienced.
We had a van with separate trunk deprtment (similar looking one below) to transport things. But some of the things ...
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Turboshaft Turbine Mathematical Model
Are there any simplified mathematical models for how two gas coupled turbines (also called a free power turbine) should interact with one another as the speed of the driving turbine changes.
(i.e.) ...
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Wrinkling paint - soluto/thermocapillarity - is it due to the primer or solvent [closed]
This is really a one-and-a-half part question.
I know that when paint is mixed with a solvent or used with a primer, it sometimes wrinkles. As I understand, a key physical phenomena here is a non-...
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Why does smoke go out the window of the car - and what if there's wind blowing instead of the car moving?
When driving a car while smoking with the window open (safety and legal issues aside), I've noticed that the smoke tends to go outside the window.
Why does the smoke go outside?
If the car is ...
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How does liquid in a ball affect its rotational acceleration down a ramp?
Suppose we have a shell with mass $M$ and radius $R$. If we let that roll without slipping down a ramp of angle theta to the horizontal, we can easily find the acceleration of the shell the instant ...
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How can two seas not mix?
How can two seas not mix? I think this is commonly known and the explanation everyone gives is "because they have different densities".
What I get is that they eventually will mix, but this process ...
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How does a hinge affect the amount of a submerged material?
Suppose I have a rod that has a density of $X <1$. If I were to submerge that rod in water (density 1), I would expect $X$ of the rod to be below water and $1-X$ of it to be above water (simple ...
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Is it possible for an object to stop sinking after a while?
Suppose you drop an object into a body of fluid (on a planet with constant gravity). Suppose the fluid is pure (as in, there are no solid granulates or bubbles present in it), and finally suppose that ...
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thought experiment involving water pressure
If I were to move the syringe up, and cause it to be stationary, how does that effect the pressure at the bottom of the pipe? How does the movement of this water effect the system setup and pressure?
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How can the Moon have such a strong effect on the ocean?
The gravitational acceleration on Earth is approximately $ 10 \mathrm{m}/\mathrm{s}^2 $. Compared to this, the tidal effect of the Moon's gravity gives a local variation in the acceleration of ...
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How to calculate the Darcy-Weissbach friction factor for shear thinning laminar flow in a pipe?
The Darcy-Weissbach friction factor for laminar flow would be $\frac{64}{Re}$
Now, having a shear thinning (non-newtonian) fluid where the viscosity is not constant how do I arrive at $Re$?
To know ...
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Apparent paradox in equation of continuity
Equation of continuity says us that if we insert some fluid in a tube, the same amount of fluid will come out from the other end. If we make a small hole in a hose pipe, water will come out with a ...
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Evaporation of water content from a solid material by applying low pressure
I have a raw material which melts at $96\ ^\circ C$. My aim is to make water content evaporate at temperature below this temperature.
I can apply vaccume oven for this. I want to know at what pressure ...
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Why do air bubbles stick to the side of plastic tubing?
I'm watching water with air bubbles flow through transparent plastic tubing. The inner diameter is a few mm. Bubbles typically are the same diameter as the tubing, with length about the same or up ...
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How much information about the scale of a waterfall can be obtained from its sound?
Is it possible to constrain the height, volume flow, or distance of a waterfall from the quantitative analysis of a high-quality recording of its sound?
As an aside, the simulated sounds of fluid ...
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What causes the structure visible in first few milliseconds of a nuclear explosion?
Following on from this question, here is a high-speed photograph of a nuclear explosion, taken about 1 ms after detonation: (source) As anna v pointed out, several similar images can be seen in a ...
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Atmospheric Circulation
What is the simplest simulatable model giving our rotating earth its 3 circulation cells (Hadley, Ferrel, Polar)?
The model should also show 1 circulation cell if the earth's rotation were stopped (or ...
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How can the surface of a liquid exist if there are no attracting molecules above it?
Okay this is probably a stupid question but here goes:
We know that molecules in a liquid are attracted from all the molecules around it so there is no net attraction. Well, then how do the ...
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Could the Bernoulli effect be causing my ceiling to come down?
Very 'applied' question, but I have nowhere else to turn, so I'm asking the physics experts here: I have a carport whose ceiling is made of very lightweight paneling. I've had several times now that ...
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Limitations of drag equation
The magnitude of the air resistance for objects with Reynolds numbers greater than 1000 is given by the formula:
Why it does not hold for objects with lower Reynolds numbers? Can I use this equation ...
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What is the term for hose fluctuating movements during flow?
What do we call it when water flowing through a flexible hose causes it to act like snake movements if the hose were disturbed?
Can this movement be explained by the Coriolis force?
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How can I keep a smaller water reservoir's water level at half available when being fed from a larger reservoir? [closed]
I'm trying to create my own ultrasonic humidifier. I ordered the misting part which works great but it only functions correctly in shallow water. So I'd like to feed from a large water reservoir to a ...
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Is it true that under water human body can sustain higher levels of acceleration?
In several sci-fi novels, I've read about humans being submerged in water (or water-like substance) to allow for a higher acceleration. Now, I'm really curious. Is this true? Can you accelerate faster ...
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Does Bernoulli's principle hold in moving reference frames? [duplicate]
Possible Duplicate:
Bernoulli’s equation and reference frames
Sometimes in train, when setting behind opening window, I can feel strong gale blowing in. The closer to the window the stronger wind ...
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Why do cars gain lift while going at a high speed?
I've been researching the physics involved with spoilers and I've just been turning up the same information about spoilers giving the back wheels of a car more traction by acting as an up side down ...
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At what velocity does sea water leave a pipe run into a fresh water lake (for equal surface levels)?
If I took a fresh water lake* whose surface is exactly as sea level, and connect it to the sea with a pipe filled with sea water, with both ends of the pipe at exactly the same depth from the surface, ...
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Energy from man-made tornadoes
Peter Thiel just paid $300,000 to Canadian inventor Louis Michaud who is working to construct useful "man-made tornadoes" or "atmospheric vortex engines" which could be components of future power ...
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Name of experiment
I'm seeking the name of or reference for an experiment I once saw in a college physics class. At the beginning of one class the instructor repeatedly wound a wiper that spread a blot of some type of ...
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Displacement of a Rock Thrown Overboard [duplicate]
Possible Duplicate:
Basic buoyancy question: Man in a boat with a stone
If you have a large boulder on a boat, in a pond, and you throw the boulder overboard and into the pond, would the water ...
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Increment of surface tension with increase of temperature
What is the reason for the increase in surface tension of molten copper/cadmium with increase in temperature?
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How deep is the Great Red Spot?
The Great Red Spot (GRS) is a very persistent storm system that's easily visible through a telescope on the surface of Jupiter. But what is the three-dimensional structure of the GRS, and how deep ...
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Measure maximum volume of liquid of a water tap
I need to know the consumption of a water tap in Liters.
I'm able to know the cross-sectional area of the pipe and how long the tap is open. With these data, how can I know the consumption/volume of ...
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Why does the milk frother on my coffee machine make so much noise?
I have a Sunbeam home espresso machine with a steam wand. The steam roars out straight from the end of the wand. When it's first placed in the cold milk it really screams! Once the milk has a bit of a ...
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How to relate speed of sound with relative humidity?
I am exploring the idea of measuring the humidity of a space using sound waves, however I am having trouble finding a mathematical relationship between the speed of sound and the humidity level.
$c_{...
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Cascade in relativistic turbulence
The Kolmogorov theory of turbulence indicates an energy cascade in turbulence. Is there a corresponding version of relativistic fluid?
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How can these fluid dynamical smoke-ring phenomena be explained?
The Navier-Stokes fluid dynamics equations, said that, as Sir William Thomson (or Lord Kelvin) predicted:
When two smoke-rings are moving in the same direction, with the same speed, one behind the ...
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Effect variable cylinder radius has on airflow
Can someone shed some light on the following problem? I'm unable to get any traction on it as I know nothing about fluid dynamics (I'm a computer engineer).
It's a problem I made up over a lunch ...
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Influence of choice of statistics on gas kinetics
In the derivation of distributions over energy states, a common assumption made is that under normal conditions (normal from a fluid dynamics standpoint, so > 300K typically) the energy states are ...