Surface tension occurs due to the tendency of liquid molecules to favor their own kind. Surface tension is important in fluid multiphase systems typically at small length and velocity
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Surface energy as thermodynamic potential
Consider free energy of sharp interface $\Gamma$
$$ \int_\Gamma \sigma\;\mathrm{d}S $$
or also free energy of diffuse interface of characteristic width $\epsilon$ given by Cahn-Hilliard/Allen-Cahn ...
4
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2answers
429 views
Solving the Young-Laplace equation for arbitrary axisymmetric geometry
Say I have a non-ellipsoidal soap bubble and I want to numerically analyse the pressure in the inner lobe of this bubble here:
The Young Laplace equation gives the pressure difference across a ...
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1answer
152 views
Lotus effect dust removal
I have found hundreds of papers describing the contact angle of water droplet sitting on hydrophobic surface and the change between Wenzel Regime and the Cassie-Baxter regime.
Now, as I understand ...
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1answer
41 views
Stability and lifetime of soap bubbles formed with light gases like helium or hydrogen?
A friend asked me if it would be possible to make soap bubbles out of a gas like hydrogen and if you did, would they float higher, faster. Due to the lower mass of light gases (compared to the air) I ...
2
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1answer
51 views
English/German translation of Latin scientific texts in general, “Principia Generalia Theoriae Figurae Fluidorum in Statu Aequilibrii” in particular
I am trying to get my hands on an English or German translation of the seminal work by Gauss on fluid shapes in equilibrium: "Principia generalia Theoriae Figurae Fluidorum in statu Aequilibrii ...
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1answer
50 views
Absorption of Water
I was just watching the videos Chris Hadfield put on youtube from space, and was wondering why water doesn't get absorbed as well onto his toothbrush in space?
And what characteristic of ...
4
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1answer
81 views
Explanation for breaking up of a stream of water into droplets
Water falling from a tap eventually breaks into droplets at a particular distance from the tap. The distance(from the tap) at which it breaks into droplets is observed to be an increasing function of ...
3
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1answer
49 views
boundary conditions for liquid with surface tension
so one uses equations of motion to describe liquids (e.g. Navier–Stokes equations). These are equations for $\vec{v}(\vec{r},t)$ with boundary conditions on the surface $S$ of the liquid (e.g. ...
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0answers
54 views
Finding Surface Tension of water at certain Temperature and Pressure
So the question is:
Using the Young-Laplace Equation (if applicable), find the surface tension (dynes/cm) for water at 20
degrees Celsius with 2.5 psi. Round to the nearest tenth.
...
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1answer
208 views
Calculational method for determining surface tensions from photograph of menisci?
How can I get from a photograph of a liquid surface to a value for the surface tension.
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1answer
100 views
Depression of Water Surface by a Needle
Given a needle of mass $m$ modeled by a cylinder of length $l$ and radius $r$ placed on an infinitely large water surface, what is
The maximum depression in the water surface; and
The equation of ...
6
votes
2answers
156 views
Hydrostatic pressure on a teapot spout
The phenomenon where water flows on the outside side of a teapot spout is named "The teapot effect", and occurs due to a difference in pressure between water and the atmosphere. Consider the image of ...
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0answers
62 views
Water evaporation
It is known that molecules at the surface are strongly attached to each other (more attraction less repulsion) than those within the bulk attraction and repulsion are balanced). This is the molecular ...
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0answers
123 views
What is the maximum tension in N the string can support [closed]
I have a length of string and I want to know the maximum tension the string can support. I tie one end of the string to the ceiling and the other end to a glass of mass 100 g. The glass is ...
16
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2answers
249 views
Stripeless cleaning of windows
Cross post: http://chemistry.stackexchange.com/q/4377/22
Last week I was discussing with a friend how we thought the stripeless cleaning of windows is achieved when using a cleaner like Windex ...
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2answers
49 views
Water entering hole at a depth, surface tension
The following is the question that very commonly appears in all HS textbooks.
A hollow sphere with a hole is taken to a depth of 40cm when the water starts entering the hole. if the surface tension of ...
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1answer
146 views
Surface tension and capillarity
The cause of surface tension is said to be asymmetry in the forces experienced by the molecules at the surface due to different interactions with air and liquid, but then the same argument also ...
6
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1answer
621 views
Collision frequency at surfaces
Collision frequency for particles in gases is well known, and collision theory is used to derive chemical reaction rates in gases, (and particles in liquid solutions as well). Using the mean velocity ...
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1answer
96 views
Why does tea rises in the pot but water don't?
I was wondering when I boil water in a pot it only shakes too much while boiling. But I could not figure out why tea rises in the pot when we boil it. it is also a liquid but it starts rising up till ...
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2answers
64 views
Why molecular forces do not obey inverse square law?
Most of the forces in physics obey inverse square law, but why molecular forces don't obey it.. Since molecular forces is also a form of electromagnetic force..
7
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1answer
320 views
How to measure a solid-solid surface energy?
Many techniques exist to measure the surface energy between a liquid and a liquid or a liquid and a gas (see e.g. the wiki page).
Methods to measure the surface energy between a solid and a fluid are ...
43
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3answers
1k views
What causes insects to cast large shadows from where their feet are?
I recently stumbled upon this interesting image of a wasp, floating on water:
Assuming this isn't photoshopped, I have a couple of questions:
Why do you see its image like that (what's the ...
0
votes
1answer
51 views
Do gasses always mix because of their Gibbs free energy?
As far as I know there are no two gasses that don't mix (excluding demixing by gravitational effects). For me, as someone working with fluids and surface tensions a lot, this means that the surface ...
6
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3answers
193 views
Why does string not wick down?
I regularly drink tea at work and I often reuse the tea bags (yes I know I'm a cheapskate). Yesterday afternoon I used a tea bag once and kept it in the cup in case I wanted another cup before I ...
2
votes
1answer
97 views
Why do some liquid metals have anomalously-high surface tension/heat of vaporization ratios?
In a didactic article, Victor Weisskopf estimated the size of molecules in a liquid from measurements of their surface tension and heat of vaporization. If atoms are exceedingly small, then only a ...
0
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1answer
82 views
Contact angle of liquid drop on surface
How do you explain point 44 of the attached pdf document on surface tension? Here's the link.
How is the direction of surface tension found out?
(I know it tangential but in which direction along ...
6
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2answers
347 views
Surface tension of solutions and mixtures
The inspiration for this question is over on cooking.stackexchange, asking more about actual measurements for commonly consumed liquids, but I'm interested more generally as well.
What determines the ...
3
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2answers
203 views
Need help understanding dynamic and static contact angles
I've run into a conceptual road block. I'm coming to you guys because I think my adviser is getting annoyed with me. The concept involves a meniscus being pulled up a cylinder. I understand that ...
2
votes
1answer
96 views
Satellite droplets in a breaking liquid jet
The famous example of a dripping faucet is an example of a Rayleigh-Plateau instability in which there is a certain jet radius below which perturbations on the surface will grow to break the jet into ...
7
votes
5answers
332 views
Zigzag flow of water along a vertical glass window
I've observed this behavior many times. When it rains, the rainwater will form vertical channels along a glass window. The flow of water is mostly confined within these vertical channels and the ...
1
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1answer
150 views
Surface Tension of a Liquid - When a liquid body is acclerating
As far as I understand it (which admittedly isn't very far), surface tension forces are made up by the tension-attractive forces of molecules at the liquid-gas/vacuum interface, such as those between ...
6
votes
2answers
626 views
Hydrostatic friction: why do water droplets stay at rest on an inclined glass surface?
Tjis is a non-expert question on a (seemingly simple) text-book topic.
The question is about "hydrostatic friction", defined as follows.
Consider a drop of water resting on a flat surface. If the ...
2
votes
0answers
58 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 ...
1
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1answer
150 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
139 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
119 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?
4
votes
4answers
484 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 ...
5
votes
1answer
167 views
Distinctive properties of liquids
The molecules are closely arranged in solids, loosely arranged in liquids and are free to move in gases... But, Why are liquids (especially water) exhibiting these distinctive properties such as ...
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1answer
107 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?
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votes
4answers
546 views
Can a “bowl” shaped liquid half-bubble be free-floating in the air?
Intent: Not looking to make-up something, I seek explanations which are possible to duplicate
Description of Phenomenon: The halved side of the bubble would be horizontal to Earth's surface, and the ...
2
votes
1answer
85 views
Beer bottle leftovers pour quickly only after waiting?
Why is it that after pouring a delicious beer from a bottle, I can hold it upside down for several seconds without reward, but if I wait a bit, the remainder presumably settles at the bottom and ...
0
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0answers
538 views
What is the tension in the string? [closed]
A light string pulls a $8.0 \space kg$ object directly upward with an acceleration of $2.45\space m/s^2$. What is the tension in the string?
4
votes
2answers
1k views
Properties of liquid and air bubbles
What is/are the properties of a liquid (e.g. viscosity, surface tension) which is conducive to formation of stable bubbles floating in air (not the bubble inside the liquid)? E.g., if soap dissolved ...
0
votes
2answers
841 views
Physics behind Water drops during falling from a tap
what is physics behind Water drops during falling from a tap.
water drop animation
A drop or droplet is a small column of liquid, bounded completely or almost completely by free surfaces.
Why Water ...
5
votes
1answer
247 views
Are coffee's properties different enough from water's to cause increased spillage while walking?
I recently found this article, which describes how...
It just so happens that the human stride has almost exactly the right frequency to drive the natural oscillations of coffee, when the fluid is ...
3
votes
1answer
301 views
Change in appearance of liquid drop due to gravity
A liquid drop is spherical in shape due to surface tension. But why does it appear as a vertical line under the free-fall due to gravity? (E.g. During a rain - falling raindrop) Is there a specified ...
8
votes
1answer
781 views
Why does water flow out of an upside-down bottle? (Rayleigh Taylor Instability)
I am currently reading the excellent book An Indispensable Truth: How Fusion Power Can Save the Planet by Francis F. Chen and I came across this explanation.
The Rayleigh–Taylor Instability
...
2
votes
2answers
4k views
'Applications' of surface tension [closed]
What are some common applications, uses, exploitations of the properties of surface tension?
Here is what I mean. A water strider can walk on water, that is a consequence of surface tension. ...
6
votes
3answers
2k views
Why does a bullet bounce off water?
It is known that bullets can ricochet off a body of water. Is surface tension responsible for this or is this the same behavior we see when an asteroid ricochets off the atmosphere? I don't think ...
2
votes
1answer
141 views
What is “surface fluid adhesion energy”?
This is related to my previous question. Pardon me for asking so many questions recently. My physics knowledge is not that good, and some answers are hard to find.
In the question in the link, I ...
