The quantitative study of how fluids (gases and liquids) move.
15
votes
1answer
625 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
0answers
131 views
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 ...
2
votes
3answers
433 views
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 ...
2
votes
1answer
107 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
1answer
141 views
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 ...
19
votes
3answers
365 views
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 ...
4
votes
1answer
153 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 ...
2
votes
4answers
136 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 ...
6
votes
1answer
120 views
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 ...
2
votes
1answer
208 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 ...
4
votes
4answers
150 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?
4
votes
3answers
183 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
101 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 ...
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 ...
4
votes
2answers
228 views
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 ...
6
votes
2answers
186 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
330 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 ...
5
votes
1answer
114 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?
14
votes
2answers
272 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 ...
-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
81 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
121 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
116 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.
...
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 ...
12
votes
2answers
121 views
Cascade in relativistic turbulence
The Kolmogorov theory of turbulence indicates an energy cascade in turbulence. Is there a corresponding version of relativistic fluid?
7
votes
2answers
188 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 ...
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 ...
5
votes
2answers
84 views
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 ...
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 ...
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 ...
8
votes
2answers
427 views
Does a wing in a potential flow have lift?
I have a hard time understanding whether or not a wing placed in a potential flow, assuming there is no viscosity and no friction with the wing, will produce a lift. I've seen several contradictory ...
2
votes
1answer
92 views
Showing symmetry of the stress tensor by applying divergence theorem to $\int\int_{\delta V(t)} \vec{x}\times \vec{t} dS$
I'm currently working through the symmetry of the stress tensor, in relation to viscous flow. I am looking at this by examining the conservation of angular momentum equation for a material volume ...
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 ...
4
votes
1answer
162 views
Can you measure the speed of water coming out of a hose by its arc?
Water comes out of a horizontally stationed hose and creates an arc as it heads towards the ground. Can I determine the speed the water was traveling in when it exited the hose by the measuring the ...
4
votes
1answer
210 views
Calculating Reynolds number for a viscous droplet
I'm trying to develop a very basic scaling law/unit analysis for viscous droplet formation, and I'd like to get some rough numerical values of the Reynolds number to play with. To be specific, I'm ...
1
vote
3answers
255 views
What are the coefficients α, β, and κ in this equation for decompression-induced gas bubble growth?
I am reading a text about gas nuclei I encountered the following formula:
$$r = \alpha + \beta \left( \frac{T}{P} \right)^\frac{1}{3} + \kappa \left( \frac{T}{P} \right)^\frac{2}{3}$$
$r$ is the ...
5
votes
3answers
419 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 ...
1
vote
1answer
214 views
Pump pressure required to fill water tower
I have a water pump at a distance of x meters from a water tower located h meters above the pump through a pipe with diameter d. I am not concerned with the exact value just want to make sure my pump ...
0
votes
0answers
137 views
What is the pressure in a vertical pipe that has moving fluid through it?
I have a system like this
When the valve is closed, pressure along any point along the thin tube may be found thru pgh. 1. What about when the valve is opened? 2. Does the top of the jar need to be ...
0
votes
0answers
122 views
Derivation of Bernoulli equation [closed]
Q.1 Tank Drainage
A large open vertical tank has three small, smooth, well-rounded orifices spaced equidistantly at $h\over4$, $h\over2$, $3h\over4$ up from the bottom of the tank (Fig. Q1). Water is ...
3
votes
2answers
413 views
Euler equation of fluid dynamics
I'm trying to obtain Euler equation for a perfect fluid in laminar or stationary flow. A particle fluid is submitted at volume forces and surface force. The fist, in my case, is giving only by gravity ...
3
votes
1answer
144 views
Rayleigh-Benard Convection
I found this nice paper about RB convection. However I am confused by what is going on page 6. In particular why we are suddenly using Helmholtz equation to find spatially periodic solutions. Aren't ...
0
votes
0answers
84 views
Wind energy used by a boat
I'm looking at different designs of ocean rowing boat. The boats are moved by a combination of factors
Human power
Wind acting on the cabins
Other elements including currents, wave action etc (that ...
11
votes
1answer
323 views
Why does my natural whistle have a maximum volume
When I whistle, I find that I can vary the volume by pushing more or less air through my mouth at once. However, when I increase volume past a point, I start to hear a blend of rushing air and a ...
4
votes
4answers
424 views
How far can water rise above the edge of a glass?
When you fill a glass with water, water forms a concave meniscus with constant contact angle $\theta$ (typically $\theta=20^\circ$ for tap water):
Once you reach the top of the glass, the water-air ...
-2
votes
1answer
103 views
Does water have the same surface tension at same temperature but different volume?
I'm making an experiment and it is written in my older questions.
Now, my question is -
Does water have the same surface tension at same temperature but different volume?
0
votes
1answer
118 views
What caused Simon Faithfull's chair to fall appart?
There is an art/science video clip on youtube, by Simon Faithful, called Escape Vehicle no.6 (chair in space). It shows a simple steel office chair, tied to a weather balloon, ascending into the upper ...
