The quantitative study of how fluids (gases and liquids) move.
3
votes
0answers
53 views
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 ...
3
votes
2answers
307 views
Why water is not superfluid?
My question is in the title. I do not really understand why water is not a superfluid. Maybe I make a mistake but the fact that water is not suprfluid comes from the fact that the elementary ...
2
votes
2answers
230 views
Will the siphoning effect help a system pump water upwards if the water's entry and exit points are at the same height?
I am looking to pump water from a pool up to a roof for solar heating (black plastic tubing) and then back into the pool with the original source water. Does the gravitational force of the water ...
2
votes
0answers
76 views
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, ...
3
votes
4answers
353 views
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 ...
1
vote
1answer
45 views
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 ...
2
votes
0answers
54 views
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 ...
2
votes
3answers
178 views
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 ...
2
votes
0answers
102 views
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.) ...
2
votes
0answers
52 views
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 ...
1
vote
1answer
105 views
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 ...
0
votes
1answer
160 views
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 ...
3
votes
2answers
350 views
Bernoulli's equation and reference frames
So I was thinking about this while driving home the other day.
I've never been quite clear on why when you drive with the windows down air rushes into your car. I thought this might be explained by ...
15
votes
1answer
627 views
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 ...
0
votes
0answers
36 views
Vlasov equation in Liddle and Lyth or Dodelson's book
I am concerned about equations 2, 5 and 6 on page 2 of arXiv:astro-ph/0606028.
The paper refers them to the book by Peebles which I don't have access to at this point.
I believe that these ...
2
votes
1answer
111 views
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 ...
5
votes
4answers
540 views
Classical Limit of Schrodinger Equation
There is a well-known argument that if we write the wavefunction as $\psi = A \exp(iS/\hbar)$, where $A$ and $S$ are real, and substitute this into the Schrodinger equation and take the limit $h \to ...
1
vote
1answer
141 views
Why does water make a liquid film?
Cut a narrow slit in a thin sheet of opaque material. Immerse the sheet in a liquid,
such as water. After removing the sheet from the liquid, you will see a liquid film in
the slit. The question is: ...
2
votes
4answers
137 views
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 ...
5
votes
1answer
156 views
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 ...
4
votes
0answers
63 views
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 ...
9
votes
1answer
74 views
How can one build a multi-scale physics model of fluid flow phenomena?
I am working on a problem in Computational Fluid Dynamics, modeling multi-phase fluid flow through porous media. Though there are continuum equations to describe macroscopic flow (darcy's law, ...
4
votes
4answers
155 views
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?
2
votes
1answer
217 views
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 ...
2
votes
0answers
55 views
Ratio of horizontal to vertical kinetic energy in ocean
What is the ratio between horizontal and vertical kinetic energy in the ocean and what is the scale dependencies of this ratio ?
14
votes
2answers
276 views
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 ...
10
votes
3answers
504 views
Which direction will Coriolis forces deflect a bubble?
If I throw a ball straight up, it deflects slightly to the west due to Coriolis forces. If instead I watch a bubble float up in water, is the bubble deflected west, east, or neither?
I think the ...
4
votes
3answers
186 views
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 ...
1
vote
2answers
102 views
Is it true that under water human body can sustain higher levels of acceleration?
In several sci-fy 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 ...
0
votes
0answers
81 views
Mass loss rate of planetary nebulae
The “interacting wind” model of planetary nebulae is based on the idea that the white dwarf phase of stellar evolution is preceded by a red giant phase. A fast wind from the hot white dwarf overtakes ...
5
votes
1answer
115 views
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?
1
vote
3answers
438 views
What is the principle behind centrifugation?
What is the principle behind centrifugation?
I understand the idea that you spin something around the centripetal force will cause an apparent force on the spinning system.
However I don't quite ...
5
votes
2answers
373 views
When does a pot not spill?
What shape for the edges of a pot and what surface properties are best for a tea pot not to spill? Apart from the cross-section from the side, how does the radius of curvature as seen from above play ...
1
vote
0answers
61 views
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 ...
6
votes
4answers
428 views
Would a fish in a sealed ball swim normally?
This question led me to wonder whether swimming would be the same experience for a fish in a full, sealed ball as it is normally.
If the fish is about 7cm from the walls of the tank, a pressure wave ...
22
votes
3answers
1k views
What is the fallacy in this infinite motion machine?
I realize this isn't possible, but I can't see why not, especially if you change the model a little bit so that the balls simply travel through a tube of water on the way up, rather than exactly ...
6
votes
2answers
189 views
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, ...
9
votes
1answer
335 views
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 ...
-1
votes
1answer
83 views
How high will water get when it hits my knee? [closed]
I was sitting in a spa hot tub and some chute coming down from a chute was hitting my knee.
I'm wondering 2 things
a) How do I calculte how high the water goes when it hits my knee
b) How much ...
0
votes
1answer
82 views
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 ...
4
votes
0answers
123 views
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 ...
3
votes
2answers
119 views
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.
...
7
votes
2answers
190 views
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 ...
0
votes
0answers
39 views
How does liquid flow effect scaling and deposition in process equipment?
I work for a project that will process large quantities of industrial chemicals. We are concerned about the amount of material that will be deposited on the inside of pipes and in process tanks. In ...
4
votes
3answers
129 views
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 ...
15
votes
1answer
252 views
Flames with no gravity?
I was watching "Solaris" (Tarkovsky) today, and noticed this: in some moment the space station changed orbit and the people inside experienced zero-gravity. At that moment, a candlestick passed ...
2
votes
0answers
135 views
Early stages of a computational model for object movement charting
We would like to build a computational model capable of accurately predicting the position of any object inside a chamber at any given time.
Inside the model we would have a number of smaller ...
5
votes
3answers
421 views
Why are Navier-Stokes equations needed?
Can't we picture air or water molecules individually? Then, why are Navier-Stokes equations needed, after all? Can't we just aggregate individual ones? Or is it computationally difficult, or ...
10
votes
5answers
558 views
Why cant one see tidal effects in a glass of water?
Why cant one see the tidal effect in a glass of water like in an ocean?
2
votes
1answer
75 views
How do I calculate speed of air on each side of airfoil?
I am doing a project on Bernoulli's principal for my High School physics course. I made an airfoil in accordance with NACA 2412 (same as a C-152).
I am going to put it in a wind tunnel where the ...
