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 tension and soap bubbles

In a common experiment, you can make a paper clip float on water due to the strong surface tension. Adding just a tiny bit of soap immediately destroys the surface tension and lets the paper clip ...
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1answer
102 views

Violation of conservation of energy… or not? [closed]

The work done by surface tension is double the increase in potential energy. This is a clear violation of conservation of energy. What is the flaw here? Work done by surface tension is \begin{align} ...
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0answers
190 views

Under what conditions does Jurin's law work? (and what are its physical basis?)

I searched answer in wikipedia (and other sites) but I found disjointed and contradictory informations. In Jurin's law article they say that the law works if the radius of the tube is smaller than ...
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0answers
93 views

Surface tension on a sphere (contact angle)

A solid sphere with radius (r) is resting upon water surface due to surface tension of the water.The contact angle is $$\theta$$ . I want to calculate the sphere weight using the water surface ...
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0answers
96 views

How much energy to overcome surface tension and create air bubble at an air/water interface

here is my question. Hope you'll help me ;-) Consider a test-tube, almost completely filled with water, and closed with a stopper. Turn it over and then remove the stopper. If the diameter of the ...
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2answers
950 views

What is the effect of surface tension on an air bubble inside water?

When an air bubble is formed inside water, and while it's still inside, does a force due to surface tension act on it? Why and where does this force act? I read somewhere that a bubble would detach ...
2
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0answers
115 views

Maximum hole size to stop a fluid passing through a solid

In a previous question, the following is answered in a general sense: Assume I have a inverse cone which holds 200ml water. I am going to cut the tip of the cone to create a small hole. How to ...
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1answer
72 views

Why is Surface film a stretched membrane due to surface tension

Surface tension is the property of liquid at rest by virtue of which the liquid surface tends to occupy minimum surface area and behave like a stretched membrane. If surface tension is property ...
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1answer
133 views

How can a droplet of liquid float on the surface of the same liquid?

This can happen during the rain, or when pouring water. Sometimes small (1-2 mm) droplets of water float on the surface for some time (a few seconds) before coalescing with the big body of water. A ...
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1answer
134 views

What causes surface tension actually? [duplicate]

Surface tension has really made me crazy! Surface tension occurs at the interface of air & water. It is a force per unit length tangential to the intersurface. But what actually causes it? One ...
0
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2answers
132 views

Bubbles of Different Size

Suppose that I have 2 bubbles of different sizes located in a liquid, and assume that both of those bubbles are close to one another. What exactly will happen to both of those bubbles? From a ...
8
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5answers
857 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 ...
2
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2answers
231 views

Water VS Soapy Water

I recently did an experiment. I have a cup of tap water, and a cup of tap water mixed with soap. I used an eyedropper to slowly drip drops of tap water onto a penny. Then I cleaned the penny, and ...
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2answers
225 views

How thick is the “skin” formed from surface tension?

I learnt in class that surface tension is caused by an unbalanced force at the surface of the liquid due to IMFs, forming a "skin" on the top. Does this mean that the skin is just one molecule thick? ...
6
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3answers
966 views

What is the meniscus shape?

What is the shape of a meniscus? I suppose that the problem is very complex, but is the solution known at least for a liquid that wets the wall in a big vessel? (exponential, maybe?)
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1answer
222 views

Why is surface tension parallel to the interface?

A text says: The surface tension of a liquid results from an imbalance of intermolecular attractive forces, the cohesive forces between molecules: A molecule in the bulk liquid experiences ...
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4answers
291 views

Why drops form spheres?

Consider a drop of water floating in an inertial frame in STP air (e.g., the ISS). Intuitively, the equilibrium shape of the drop is a sphere. How would one prove that? Is it equivalent to showing ...
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2answers
931 views

Viscosity and surface tension

Both viscosity and surface tension are dependent on the intermolecular forces between the molecules of the liquid. Supposing from this, shouldn't there be a directly proportional relationship between ...
7
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5answers
9k 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 ...
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2answers
155 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
198 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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3answers
307 views

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
1k views

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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4answers
311 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
120 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
191 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
143 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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2answers
1k 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
298 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
3k 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
55 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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3answers
4k views

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?
2
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2answers
676 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
29 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 ...
5
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3answers
178 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 ...
5
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1answer
637 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
165 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 ...
6
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1answer
432 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
729 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
95 views

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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4answers
966 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 ...
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1answer
58 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 ...
5
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1answer
246 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 ...
0
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1answer
1k views

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 ...
0
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1answer
656 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 ...
6
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1answer
114 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 ...
6
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2answers
2k views

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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0answers
440 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 ...
2
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1answer
50 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 ...