Images capture split personality of dense suspensions

Mar 30, 2012
In this image, lighted from the front, water containing zirconium dioxide particles measuring 850 microns in diameter detaches from a nozzle. The suspension neck maintains a symmetric profile until the neck gradually narrows to a width of only one particle, when the liquid surrounding the particles ruptures. Credit: Marc Miskin/Heinrich Jaeger

Stir lots of small particles into water, and the resulting thick mixture appears highly viscous. When this dense suspension slips through a nozzle and forms a droplet, however, its behavior momentarily reveals a decidedly non-viscous side. University of Chicago physicists recorded this surprising behavior in laboratory experiments using high-speed photography that can capture action taking place in one hundred-thousandths of a second or less.

UChicago graduate student Marc Miskin and Heinrich Jaeger, the William J. Friedman and Alicia Townsend Friedman Professor in Physics, expected that the dense suspensions in their experiments would behave strictly like viscous liquids, which tend to flow less freely than non-viscous liquids. Viscosity certainly does matter as the particle-laden begins to exit the nozzle, but not at the moment where the drop's thinning neck breaks in two.

New behavior appears to arise from feedback between the tendencies of the liquid and what the within the liquid can allow. "While the liquid deforms and becomes thinner and thinner at a certain spot, the particles also have to move with that liquid. They are trapped inside the liquid," Jaeger explained. As deformation continues, the particles get in each other's way.

"Oil, honey, also would form a long thread, and this thread would become thinner and break in a way characteristic of a ," Jaeger said. "The particles in a dense suspension conspire to interact with the liquid in a way that, when it's all said and done, a neck forms that shows signs of a split personality: It thins in a non-viscous fashion, like water, all the while exhibiting a shape more resembling that of its viscous cousins."

It took Miskin and Jaeger six months to become convinced that the viscosity of the suspending liquid was a minor player in their experiments. "It is a somewhat heretical view that this viscosity should not matter," Jaeger said. "Who would have thought that?"

Miskin and Jaeger presented their results in the March 5 online early edition and the March 20 print edition of the Proceedings of the National Academy of Sciences.

In their experiments, Miskin and Jaeger compared a variety of pure liquids to mixtures in which particles occupy more than half the volume.

"The results indicate that what we know about drop breakup from pure liquids does not allow us to predict phenomena observed in their experiments," said Jeffrey Morris, professor of chemical engineering at City College of New York. "The most striking and interesting result is the fact that, despite these being very viscous mixtures, the plays little role in the way a drop forms."

Few studies have examined droplet formation in dense . As Morris noted, such work could greatly impact applications such as inkjet printing, combustion of slurries involving coal in oil, and the drop-by-drop deposition of cells in DNA microarrays.

Scientific Defiance

In these applications particles often are so densely packed that their behavior defies a simple scientific description, one that might only take into account average particle size and the fraction of the liquid that the particles occupy, Morris explained. The UChicago study showed that particles cause and often protrude through the liquid, rendering any such description incomplete until fundamental questions about the interface between a liquid mixture and its surroundings are properly addressed.

"Miskin and Jaeger provide arguments for the importance of these protrusions in their work and suggest that the issue is of broader relevance to any flow where a particle-laden liquid has an interface with another fluid," Morris said.

Miskin and Jaeger verified their results by systematically evaluating different viscosities, particle sizes and suspending liquids, and developed a mathematical model to explain how the droplet necks evolve over time until they break apart.

One initially counter-intuitive prediction of this model was that larger particles should produce behavior resembling that in pure water without any particles. "If you want to make it behave more like a pure non-viscous liquid, you want to make the particles large," said Jaeger, who finds himself intrigued by nature's seemingly endless store of surprises.

Miskin and Jaeger indeed observed this when the particle size approached a significant fraction of the diameter, making the particles visible to the naked eye.

"You think you have a pretty good idea of what should happen, and instead there's a surprise at every corner. Honestly, finding surprises is what I love about this work," Jaeger said.

Explore further: On-chip topological light: First measurements of transmission and delay

More information: "Droplet formation and scaling in dense suspensions," by Marc Z. Miskin and HeinrichM. Jaeger, Proceedings of the National Academy of Sciences, March 20, 2012, Vol. 109, No. 12, page 4389-4394.

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User comments : 13

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Callippo
1.1 / 5 (7) Mar 30, 2012
When this dense suspension slips through a nozzle and forms a droplet, however, its behavior momentarily reveals a decidedly non-viscous side.
This behavior shouldn't be surprising for aether physicist. An analogy of this experiment at the quantum scale: the thin neck of kitchen salt reveals its surprising stretchiness. In this experiments the atom nuclei play a role of zirconia particles and the electrons do play a role of water molecules, which are surrounding and gluing them. For formally thinking physicists these two experiments would appear completely unrelated - yet their deeper connection exists, if we would use the particle simulation of both phenomena.
Callippo
1 / 5 (6) Mar 30, 2012
The very similar mechanism is related to high mobility of electrons at the surface of thin graphene layers and/or even to such exotic behaviour, like the supersolidity phenomena. The increasing of the surface/volume ratio leads to the pronounced decreasing of viscosity of the bulk phase, because the fermions, which are forming it are getting to behave like the anyons, i.e. half-bosons and they're losing friction in similar way, like the atoms inside of superfluid hellium. The crunching of wet snow is the manifestation of this temporal superfluidity.
Skultch
4.9 / 5 (7) Mar 30, 2012
I'm probably going to regret getting into it with you, but it seems that not realizing that analogy and word-play is not how science is done is one of the things wrong with you.

Also, COLD snow within a certain Range of moisture content is crunchy. Faceted grains and air pockets caused by melt-freeze are what make it crunchy and you don't need an aether-scope to know that. I've been around snow for 30 years at multiple widely ranging altitudes and latitudes, and I don't recall it ever being crunchy otherwise. If you are really interested in the Classical explanation, take an avalanche risk course. It makes more sense than what you said.
Callippo
1.3 / 5 (4) Mar 31, 2012
Faceted grains and air pockets caused by melt-freeze are what make it crunchy
This doesn't explain the regelation of ice, which is rather exceptional between other materials. In addition, the snow bellow certain temperature doesn't crunch anymore.
but it seems that not realizing that analogy and word-play is not how science is done is one of the things wrong with you.
I'm using these analogies JUST BECAUSE I do realize, how contemporary science managed to ignore with its overly deterministic approach for years the important findings and important connections (if not equivalence) of many concepts (gravitational waves - CMBR radiation, antimatter - dark matter, etc). So please don't tell me, this is not the contemporary science - this is exactly the reason, why I'm presenting it here. I'm not here for parroting of things, which everyone can google or find in the common textbooks.
Callippo
1 / 5 (4) Mar 31, 2012
Because the picture is worth of thousands of words and video is worth of hundreds of pictures, the link to the article supporting information is here http://www.pnas.o...lemental It's evident, this suspension exhibits fast relaxed thixotropy, i.e. its viscosity gets down during strong sheer stress temporarily.
Skultch
5 / 5 (4) Apr 01, 2012
Show your math for the people that can review it

or

http://en.wikiped...7s_razor
Callippo
1 / 5 (4) Apr 01, 2012
Show your math for the people that can review it
How the math based on some analogy can disprove this analogy? For example, Kepler based it's laws on the assumption, the Earth is revolving around the Sun. Could these laws disprove their assumption, after then? And vice-versa: the fact, some formal model describes the observations well (the epicycle model of Kepler era) doesn't mean, this model is logically correct. Whole the math is based on predicate logics, which has been used for its derivation: if this logics is wrong, whole the subsequent derivation is wrong as well. This is a reason, why in formal math no conjencture is used, until it's not proven at the logical level. Unfortunately, the contemporary physics lacks this step in derivations of its models: it constructs them without deeper understanding, how their physics is actually working. This approach may appear faster and effective first - but the lack of logic will pop out soon or later (string theory as an example).
Callippo
Apr 01, 2012
This comment has been removed by a moderator.
Callippo
1 / 5 (4) Apr 01, 2012
Just the fact, the physicists are using to describe the physical processes with formal equations prohibits them to see their similarity often. Their equations have often different form or they're using different symbols for variables: in this way the physicists overlook the connections of phenomena and concepts even under situation, when this connection is quite apparent for untrained eye. For example, the physicists are looking for manifestation of extradimensions and/or gravitational waves, while ignoring the Casimir force or CMBR noise.
Skultch
4.8 / 5 (5) Apr 01, 2012
Yep. Regret. I've seen enough of your arguments with others to know that you aren't going to get it.

1. Show the math that aether theory has more accurate predictions than accepted QM/GR/M-Theory/etc. (filling knowledge gaps with hypothesis doesn't count)
2. Get it peer reviewed.
3. Collect your Nobel Prize.
4. Brag about it on Physorg.
5. Receive numerous apologies.
6. Profit.

Talk to you then. Later.
Anda
5 / 5 (3) Apr 02, 2012
As always, water ripples with his childish analogies...
I like this argument: no maths because if they are based in analogies they can't prove them :)
Thanks for the entertainment Rawa
Kinedryl
1 / 5 (3) Apr 02, 2012
Many physical problems have no mathematical formulation yet. I'm pretty sure, you wouldn't accept Galileo proofs being in his era as well - this illustrates, the contemporary physicists don't differ from medieval priests so much. For example, Galileo disproved geocentric model with order of Venus phases by this picture http://ircamera.a...phas.jpg Try to formulate this evidence mathematically, or it is invalid. If you cannot do it, why I should do the same with my evidence?
MarkyMark
1 / 5 (1) Apr 03, 2012
Many physical problems have no mathematical formulation yet. I'm pretty sure, you wouldn't accept Galileo proofs being in his era as well - this illustrates, the contemporary physicists http://aetherwave...day.html Try to formulate this evidence mathematically, or it is invalid. If you cannot do it, why I should do the same with my evidence?

Err i think you used the wrong puppet here buddy!!

Anyway i love your posts as they are very entertainng, a bit like Olivers the he was a real master at it. Darn i miss his commedy a bit now since he left us!!!.

Does anyone jnow why he left? Was he convicted and imprissoned for Child sex offences?

Cant be bothered to wast my time looking but if someone jnows pls PM me.
Skultch
5 / 5 (1) Apr 06, 2012
Some confirmation that Aether "theory" is not science: (Reddit is onto this crank, also)

http://www.reddit..._why_is/