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

learn more… | top users | synonyms (1)

1
vote
1answer
463 views

Problem with ring-method of du Nouy for calculating surface tension

I need to calculate the surface tension of a liquid with the ring-method of du Nouy and the correct formula to use is: $\gamma = \frac{F}{4\pi R}$ I understand that the surface tension is the ...
19
votes
4answers
2k views

Why does a cork float to the side of a glass?

What is this physical phenomenon and when it's happen ? Please take a look at this picture: Link to picture Notice: This is a cork ball attracted to sides of a glass of water
3
votes
2answers
89 views

Does quasi-static motion imply zero energy dissipation?

When a droplet is deposited on a surface with some surface roughness and subsequently tilted it can stick due to pinning (think of droplets on a window after rain). What I am interested in is ...
7
votes
2answers
544 views

How is the water meniscus at the edge of a capillary tube

Suppose we have a capillary tube in which water can rise to a height of x cm. If we dip the tube such that the height above the surface is less than x, then how will the water meniscus be at the edge ...
5
votes
2answers
397 views

Can water pressure ever be high enough to trap gas bubbles or keep them from surfacing?

Can water pressure ever become high enough to trap gas bubbles and/or keep them from surfacing?
1
vote
1answer
1k views

Problem understanding the capillary action equation

As you know the equation of capillary action id given by: $h=\dfrac{2\gamma\cos\theta}{\rho gr}$ Where: $h$ is the height the liquid is lifted, $\gamma$ is the liquid-air surface ...
4
votes
1answer
2k views

Why does water sometimes form bubbles when I pour it into a glass?

Sometimes when I'm filling up a container with water from the tap, bubbles will form on the top of the water. They look a little like soap sud bubbles, but there's no soap suds present. I notice, ...
1
vote
2answers
246 views

Water doesn't flow above the rim, one reason is surface tension. Is another reason viscosity?

According to Surface tension, water molecule don't get the force from outside and get little bit outward. Is one reason viscosity? Let's look at the water in a fully filled glass. No part is outside ...
4
votes
1answer
148 views

Variational principles: Meniscus

In determining the shape of a meniscus, we have to minimize the energy per unit length along the direction perpendicular to the cross-section of the meniscus: $$\frac{E}{L}=\int^L_0 dx [\gamma ...
15
votes
1answer
204 views

What are the equations of motion of a hole in a soap bubble?

Imagine the following situation: I have a thin stationary water film, like a soap bubble, suspended inside a large ring. I throw a small loop of string onto the film and punch a hole inside it. How ...
5
votes
2answers
815 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 ...
6
votes
0answers
253 views

Surface tension between water (liquid) methane (gas)

In my project I should calculate surface tension between water and methane with lammps. I write the program.I use SPC model for water and $l_j$ for methane and water - methane. But now I don't know ...
3
votes
5answers
302 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 ...
2
votes
1answer
137 views

Why do new towels dry better after a few uses?

Most of you will be familiar with the phenomenon: you have bought a new towel and you first have to wash it or use it a couple of times before it starts to work properly, i.e. dry your body after ...
2
votes
1answer
278 views

Dynamic simulation of surface tension [closed]

Is there any substantial body of work in physics on dynamically simulating effects of surface tension on liquids? The texts i found so far on fluid dynamics all seem to ignore surface tension, ...
0
votes
1answer
79 views

Is there a way to define a function of a meniscus curvate?

If you cut a thin slit in thin opaque material and then put it into water and pull it out, the meniscus will be formed in the slit. For my research I need to know if it is analytically possible to ...
9
votes
3answers
232 views

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 ...
1
vote
1answer
318 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
votes
1answer
118 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 ...
0
votes
1answer
125 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
votes
1answer
391 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
votes
1answer
290 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. ...
0
votes
1answer
532 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.
0
votes
1answer
311 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
470 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 ...
16
votes
2answers
357 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 ...
0
votes
2answers
201 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 ...
1
vote
1answer
3k 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
votes
1answer
889 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 ...
2
votes
1answer
289 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 ...
0
votes
2answers
153 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
votes
1answer
968 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 ...
53
votes
3answers
2k 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
82 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 ...
2
votes
1answer
218 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
votes
1answer
121 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
votes
2answers
607 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
votes
2answers
525 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
307 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 ...
8
votes
4answers
582 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
vote
1answer
198 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
1k 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
90 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
vote
1answer
230 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: ...
5
votes
1answer
193 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?
5
votes
1answer
287 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 ...
-2
votes
1answer
145 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?
2
votes
1answer
118 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 ...
4
votes
2answers
2k 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
2k 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 ...