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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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 ...
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2answers
119 views

Why is there a limited range of possible soap bubble size?

Soap bubbles are never "too small" or "too large". What defines the range of possible diameters of a soap bubble? Related questions: Why do steam bubbles increase in size as they rise, Why is the ...
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1answer
123 views

What is the maximum height for a puddle of water, assuming stp?

I wonder if anyone has figured this out. Assuming, standard temperature and pressure(273 K and 1atm), what is the maximum height of a water puddle on a flat surface? There might be some other factors ...
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finding equation of a water droplet

I have a water droplet which is falling down through its gravity. I've supposed that my droplet is an ellipsoid and I want to find the equation that represents this ellipsoid in XYZ coordinate system. ...
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3answers
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How to prevent water droplets becoming larger on the tip of a nozzle?

I use an ordinary syringe to generate a single water droplet. However, it is not usually able to make a droplet smaller than 1 mm (because of surface tension forces, inner diameter of needle, etc.) ...
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245 views

Why does a bubble take a spherical shape?

I suspect this has something to do with thermodynamics and the isoperimetric inequality and I'm interested in a mathematical derivation of this result.
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1answer
87 views

Can a liquid with angle of contact as 90 degrees with a solid surface definitely wet it?

Can we conclusively say something about wetting conditions at this boundary value of angle of contact ($90^o$)?
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0answers
130 views

What does having high/low surface tension mean?

I am talking about air-liquid, air-solid, and solid-liquid interfaces. While studying about the shape of meniscus of a liquid in a glass tube, I came across a conclusion that surface tension at one ...
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2answers
123 views

Why do Oreo crumbs float to a single glob at the very center in a glass of milk? [duplicate]

I had Oreos and milk a while ago and left my half-full cup of milk out on the counter. Afterwards I noticed that the crumbs had surfaced in a circular coin-sized glob, and just now I looked again to ...
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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
279 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 ...
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4answers
2k views

What is the physics behind a soap bubble?

A soap bubble is an extremely thin film of soapy water enclosing air that forms a hollow sphere with an iridescent surface. What fluid dynamical process occurs during the popping of a soap bubble?
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0answers
54 views

Why is there roughness on every surface?

Why is there roughness on every surface? I think a smooth surface could better minimize the surface energy. Besides, why does the roughness happen to be fractal?
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Why doesn't rain fall down in streams (as opposed to drops)

Why is it that raindrops don't collide and 'stick together' on their descent to Earth, arriving in streams rather than separate drops?
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2answers
568 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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0answers
28 views

Floating subject on a surface of water

If We put a small floating object (penoplast granule) on a surface of water it performs spiral like movements and eventually sticks to a side of a vial. What physical forces are involved? I'm ...
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154 views

Will a drop of liquid flow from from the wide opening to the narrow opening of a thin funnel by the effect of air pressure?

We have a funnel that is thin enough to keep a drop of liquid inside it as shown in this figure. Assuming that the funnel is placed on a horizontal table, will the drop flow from the left side to ...
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1answer
579 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
40 views

Water Droplet Saturation Phenomenon

What is the term used to describe the behaviour of (for example) a water droplet in free fall when it has reached a certain speed and then the force on the droplet causes the larger droplet to ...
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0answers
146 views

How do adhesive and cohesive forces affect surface tension? [closed]

Surface tension appears at the interface of two immiscible fluids if the cohesive force of attraction is more than adhesive force. What will be the physical effect if the adhesive force is more than ...
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1answer
353 views

Why will two bubbles floating on water surface attract each other?

Two identical bubbles floating on water surface will form clumps, according to the "cheerio effect". But what's the detail about the force? It's necessary to calculate the shape of water surface, in ...
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4answers
714 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 ...
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0answers
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What kinds of reactions happen when bubbling air through water?

Mostly I have seen air bubbling used to remove impurities in the water itself, like exemplified in this course packet. This is called "Sparging," but I have yet to learn much about transfer between ...
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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 ...
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1answer
47 views

Air vs. Water attraction of Oxygen Molecules

The air we breathe is made up of nitrogen and oxygen gases. The water in a pond is made of a single hydrogen/oxygen molecule. If it wasn't for the surface tension on top of the water, oxygen molecules ...
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1answer
230 views

Surface Tension - Lung Alveoli

So, the way I understand this is as follows : The alveoli (pretend they're bubbles) have diameters of the order of microns implying a massive pressure required to inflate them by the Young-Laplace ...
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1answer
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water surface tension and buoyancy

When you put a little pin on the surface of water and it floats. Is this because of surface tension or buoyancy? Can somebody also draw a force diagram for me to explain how water surface tension ...
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559 views

Determine the maximum capillary rise

The problem I have is this: A capillary tube is immersed vertically in water. Knowing that water starts to evaporate below 2kPa, determine the maximum capillary rise and tube diameter. Assume the ...
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1answer
105 views

What causes the 'tears' in yoghurt drinks?

Fluid dynamical instabilities are present in many different everyday things. The famous tears in wine for example are a classical example of a Marangoni effect, where surface tension gradients due to ...
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Does water have surface tension in a vacuum?

I could be totally wrong here but I was thinking about water surface and what creates that. My thought is it is the thin mixture of water and air separating the two. This mixture creates the boundary ...
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363 views

Measuring the solid air surface tension

For hydrophilic and hydrophobic materials, $Y_{SG}$= Interfacial tension between the solid and gas $Y_{SL}$ = Interfacial tension between the solid and liquid $Y_{LG}$ = Interfacial tension ...
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1answer
49 views

Evolution of minimization of surface tension

What are governing equations (or/and variational principles) for evolution of a simply connected body of water in vacuum? Initial state - for time $t=0$ we have a bounded simply connected set ...
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1answer
79 views

Modeling Water Surface Impact

I have a project that is to model the wave equation in a pond due to a pebble being thrown in. The project is quite simple as all we really have to model is the wave equation with an initial ...
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1answer
109 views

Time taken in changing surface tension [closed]

I had read some where that the water in glasses has a high surface tension, but in lota (It is sort of a spherical container) the surface tension is lower. How can I measure the water surface ...
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How much of the forces when entering water is related to surface tension?

When an object enters water with high velocity, (like in Why is jumping into water from high altitude fatal?), most of it's kinetic energy will be converted, eg to accelerate water, deform the object ...
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51 views

Relationship between existence of forces on a liquid surface, and the tendency to decrease the surface area

What does the following sentence imply? "Because of the existence of forces across any line in the surface of a liquid, the surface tends to shrink whenever it gets a chance to do so." Why does the ...
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1answer
141 views

Measuring cross-section area of a flexible tube (5mm dia approx)

I want to measure the avg. inner cross-section area of a flexible tube of outer diameter 5mm. Since the cross-section isn't a circle exactly, use of vernier caliper to measure inner diameter fails. ...
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1answer
177 views

Water falling, why does it spin?

I have noticed that water, when falling will rotate. Looking closely at a thin stream from a faucet and placing a flat object mid stream you will see the water is rotating. The further down the stream ...
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4answers
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In the formula for the mass of a drop of water on the end of a tube, is r internal or external radius?

In the formula for the mass $m$ of a drop of water forming on the end of a vertical capillary tube, $$m = \frac{2\pi r \gamma}{g},$$ does $r$ refer to the internal or external radius of the ...
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1answer
63 views

Resource(s) for developing a good understanding of surface tension?

I have read through several junior undergraduate level explanations of surface tension. Here is a typical presentation at that level: Molecules at the surface of a fluid experience approximately ...
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62 views

Why do floating objects attract? [duplicate]

Objects floating on the surface of calm water seem to be attracted to one another and tend to come together in a drift. Is this attraction like gravity?
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1answer
78 views

What are circles on broth (eating soup) surface?

Think about broth in the soup, usually it has circles on its surface. What are their properties? Why there are many of them (not a few big blobs)? Are they depended on liquid's temperature? What needs ...
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2answers
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Why doesn't the water spill out?

In this experiment, a number of coins are put into a cup full of water, without spilling it. http://www.youtube.com/watch?v=N2mKpZHnEzw Firstly, let me clarify one thing. If you fill up a cup ...
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1answer
310 views

Formation of meniscus

If molecules at the surface of a liquid have higher energy and want to minimise the surface area, then why is a mensicus formed which of course increases the surface area?
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2answers
156 views

What is a good model for computing water dropping on a surface?

Before introducing my question I would like to outline the fact that I'm a coder, so I can be wrong when using some kind of terminology. What is a good model for computing the flow, the shape and all ...
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0answers
186 views

Needle Floating on a Water Surface

So, I'm trying to find the largest radius of a needle before it ends up sinking, and I know that it's a balance of needle weight vs surface tension. However, I'm not really sure how the surface ...
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1answer
155 views

where does the energy of water droplet go?

My experiment: I took a string (3 mm diameter and wet) and a water source (1 drops per 2 seconds). Then I attached the string to the water source. The string was then tied to ground Observation : ...
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2answers
320 views

Tension in string due to surface tension

Suppose you take a loop of string and place it on the surface of a liquid, the string should become taut due to surface tension. How would you be able to calculate the tension in the loop of string? ...
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1answer
107 views

Non-determinitric flow of water stream on vertical porcelain surface

I noticed several times while washing my hands that accumulated water when starts streaming vertically does not flow vertically in straight line on vertical porcelain surface under the force of ...
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Why is it tension in surface tension?

Why is it called surface tension not surface compression?