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## Using Non-Newtonian Fluids To Fill Potholes260

sciencehabit writes in with a link about a group of students who have come up with an interesting idea about how to fill potholes. "Non-Newtonian fluids are the stars of high school science demonstrations. In one example, an ooey-gooey batter made from corn starch and water oozes like a liquid when moved slowly. But punch it, or run across a giant puddle of it, and it becomes stiff like a solid. Now, a group of college students has figured out a new use for the strange stuff: filler for potholes."
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## Using Non-Newtonian Fluids To Fill Potholes

• #### More Patents (Score:5, Insightful)

on Wednesday April 11, 2012 @04:41PM (#39650025)

The students plan to patent their invention, so they won't divulge their exact formulation,

Exact formulation isn't necessary for this application, as every 7th grade science class learns it by trial and error with a \$1.29 box of corn starch.
You can do this in your kitchen in 10 minutes, and the stuff is fun to play with but nobody has found a real good application for it in over a
hundred years.

The trick in keeping the right proportions of water and starch, something that rain and sun will contrive to disrupt. Burst their bag and you have a big mess.
If you stop with a tire one of these, such as at a traffic light, you will sink into it, because given constant pressure, it will flow. It only resists changing pressure, or active kneading, not static weights.

But the beauty here is the rapidity with which these can be thrown down, and they fact that they flow into the pothole, conform to its shape, and thereby resist being ejected by cars.

P.S. It will be a cold day in hell before you find Police patching potholes.

• #### Re:More Patents (Score:5, Insightful)

on Wednesday April 11, 2012 @05:10PM (#39650301)

If they have something that's really worthwhile, it's a combo system that uses the NNF to fill the hole to a level surface, the a traditional asphalt cap over that. The beauty of the NNF is that it fills the gaps and voids quickly, but still provides strong resistance for shock from cars driving over.

I also assume that they've used something non-biodegradable, corn starch wouldn't make it very long exposed on a highway.

Of course I could RTFA, but what would happen to my Karma if I did that?

• #### Re: (Score:2)

Corn Starch mixtures also have a nasty side effect of growing mold after a period of time.

• #### Re: (Score:3)

Corn Starch mixtures also have a nasty side effect of growing mold after a period of time.

That's what benzylkonium chloride is for.

• #### Re: (Score:3, Funny)

of course! benzykllul...lolo...konoleum chloride! why didn't i think of that?
• #### Re: (Score:2)

The beauty of the NNF is that it fills the gaps and voids quickly, but still provides strong resistance for shock from cars driving over.

Except that it's in a bag, which would prevent that, wouldn't it?

• #### Re:More Patents (Score:5, Insightful)

on Wednesday April 11, 2012 @10:46PM (#39653673) Homepage

This site puts it well http://www.davis-stirling.com/MainIndex/Asphalt/tabid/3350/Default.aspx [davis-stirling.com]. Potholes simply reflect cheap ass government focusing taxpayers dollars on kickbacks rather than on routine road maintenance. When you have pot holes, that represent either an unusual problem (flooding, water main burst etc.) or quite simply a break down in the proper duties of local government and or state government.

If you have pot holes in a major city and you ain't firing your elected representatives and replacing them with new representatives than you're bloody idiots and, yes according to Google street view US infrastructure roads and footpaths largely looks like shit.

• #### Re: (Score:2)

assuming they are using corn starch.

Maybe the have some material that is non Newtonian, but hardens with applied heat? that way you could pour the liquid in at room temperature. Which would be awesome and much cheaper.Assuming it meet required material guidelines.

• #### Re:More Patents (Score:5, Interesting)

on Wednesday April 11, 2012 @05:28PM (#39650513) Homepage

the stuff is fun to play with but nobody has found a real good application for it in over a hundred years.

Viscous couplings have been made using dilatant (non-newtonian) fluids for quite a while now, at least since the 1985 VW Transporter 'Syncro' (4WD rear-engined van made by Volkswagen, quite popular here in Europe).

• #### Re: (Score:2)

The trick in keeping the right proportions of water and starch, something that rain and sun will contrive to disrupt. Burst their bag and you have a big mess.

Caption of the first image at the top of the page of TFA "Prototype. Waterproof bags filled with a shear-thickening fluid that resists compression when run over by traffic."

• #### Re: (Score:2)

What are the bags made of and how long will they last with traffic constantly running over them? How long can the material maintain its waterproof characteristics?

If it works, I'd love to have a pair of boots made from that miracle material.
• #### Stopping on it? (Score:4, Insightful)

on Wednesday April 11, 2012 @04:46PM (#39650069)

Neat idea and looks to be working well for cars moving fast.
What about traffic jams though where cars come to a stop on these bags. I'd imagine they'd sing in somewhat and might have trouble moving out of the hole from there.

• #### Re:Stopping on it? (Score:5, Interesting)

on Wednesday April 11, 2012 @05:06PM (#39650249) Journal

Worst case scenario, you're back to having a pothole. As long as the bag can "bounce back" after being sqeezed it's not so bad. Also, it would feel weird to slowly sink but it wouldn't ruin your suspension and you should be able to drive out of it. The problem with the potholes is when you hit them at speed and ruin your tires and/or suspension.

• #### Re:Stopping on it? (Score:5, Insightful)

on Wednesday April 11, 2012 @05:11PM (#39650311)

The fluid is kept in a bag that is then covered by a black cloth to make it less visible to drivers. Even if they did sink into the pothole while at rest, they could still get out easily, and the bag would simply flow back into its original shape after a few seconds. The only hazard or concern I see there is if the next car drives over it before it flows back to being flat, in which case they may get a bit of a bump, but still no worse than the original pothole itself.

• #### Re:Stopping on it? (Score:4, Interesting)

on Wednesday April 11, 2012 @09:49PM (#39653295)
I see another problem...what happens if the bag gets knocked out of the hole? Now you have a sizable road hazard which acts a lot like a big rock to all the cars hitting it. You'd have to ensure that the bag is fully anchored into the hole. Worst case, you could have the bag get pulled up by the friction of a tire and thrown back into a car behind...I'd imagine that would not lead to good things.
• #### Re: (Score:2)

I would love to see what happens when it rains.

The quickest way to ruin this stuff is to over-dilute it with water. Then it acts like....water...with some powder dissolved in it. Not great, or non-newtonian at all.

• #### Re: (Score:2)

Still better than stopping on an empty pothole.

• #### What happens when people take them? (Score:4, Interesting)

on Wednesday April 11, 2012 @04:48PM (#39650093)
I cannot foresee a way to prevent people from stealing these. I mean, I know it sounds silly, but renters steal light fixtures, for crying out loud.
• #### Re: (Score:3)

A free cement bag of Silly Putty? What couldn't you do with one of those?

It's similar to a city leaving Giant Slinkies all around town.

• #### Re: (Score:2)

wait! we can steal the light fixtures? I've seen bulbs, and I've put in crappy incandescents instead of leaving my LEDs behind, but that's different.

• #### What happens when a car stands still on them? (Score:4, Insightful)

on Wednesday April 11, 2012 @04:49PM (#39650097) Homepage

Traffic isn't always flowing, after all. (And traffic itself acts like a non-Newtonian fluid, as well.)

• #### Re:What happens when a car stands still on them? (Score:5, Interesting)

on Wednesday April 11, 2012 @05:03PM (#39650223) Homepage Journal
No, this is a feature. These can be used to pave "no parking/no standing" zones. Rule breaker's vehicles will get eaten, by the pavement. If used on streets, it will encourage drivers to avoid congested areas.
• #### Re:What happens when a car stands still on them? (Score:5, Interesting)

on Wednesday April 11, 2012 @07:47PM (#39652201)

Interesting. .. actually on the same vein .. why not make speed bumps out of non newtonian fluids? Just fill a cylindrical rubber (like a hose with a huge diameter) with the fluid .. people going slow will feel hardly any bump while speeders get the full effect?

• #### Wonderful idea ... (Score:3, Insightful)

on Wednesday April 11, 2012 @04:57PM (#39650161)
It's a great idea ... until you read that "The bag might cost a hundred dollars but you can reuse it a hundred times, and by that time you'd be saving a ton of money". So yes, great idea ... until kids start stealing them BECAUSE THEY CAN.

Also : Read the AC posts in any slashdot story and you'll be quick to agree : the world is filled with angry kids.
• #### Re: (Score:2)

There are angry kids. It's not even a majority though. You won't here about the other ones.

• #### Re: (Score:2)

That assumes that kids can steal them. Mind you, it's in the middle of traffic. Also, the protective layer on the top could be painted to the colour of the surrounding asphalt, acting as a disguise. Even if they can, this would still be useful on roads outside of the city, or in streets with cameras.

• #### Re:Wonderful idea ... (Score:5, Funny)

on Wednesday April 11, 2012 @05:45PM (#39650661)
Another idea: let's use pitch - it maybe not a non newtonian fluid (but again, it may be... just haven't had enough time to check), but it is a fluid [wikipedia.org] nonetheless.

Now, because it tends to stick on the tires (and the use of mats tends to be expensive over time), I suppose we can mix the pitch with sand and/or fine gravel before filling in the holes - should keep the pothole filled for some years without the need of revisiting it... what a boon for the taxpayers. (hmmm... I think I'm going to patent this)

• #### Re: (Score:2)

As a kid I had a friend that would steal anything. I went to his room once and saw this big metal box and about 20 feet of black hose. I asked him WTF it was. He said someone put it on the side of the road to count cars and he just had to have it.

• #### This couldn't happen last week? (Score:2)

If it's cheap, and will get towns to fix shit fast, then I'm all for it.

Blew \$300 on a new tire last week. Had to swerve so I wouldn't hit a deer, and went straight over a pothole.

• #### Re:This couldn't happen last week? (Score:5, Insightful)

on Wednesday April 11, 2012 @05:17PM (#39650387)

Use cheaper tires?

• #### Re: (Score:2)

Had to swerve so I wouldn't hit a deer, and went straight over a pothole.

If you had to swerve you didn't go straight over.

• #### Re: (Score:2)

You don't happen to drive an SUV/Soccer Mum car do you?
• #### Re: (Score:2)

I drive a honda accord! I had no idea the tires were so expensive. Pilot Mxm4

• #### Re: (Score:3)

That's a huge amount for a single tyre. Someone is ripping you off
• #### Re: (Score:2)

That's not actually that bad a price for that tire, but it's not really that great a tire. You could get something better from Kumho for half the price.

• #### Re: (Score:2)

This isn't "fixing" anything. It's a temporary thing and as other have pointed out if it's not stolen its likely to be destroyed by water or birds or chemical contamination or any number of things. A "real" cheap temporary fix is cold mix asphalt applied to the pothole until hotmix asphalt is available. Cold mix is durable and reliable, lasts long enough to get you through a winter hot plant shutdown and has no value to thieves nor is it any different chemically from the regular hot mix asphalt other than t

• #### Re: (Score:2)

If cold mix asphalt is so great, then what's the advantage of hot mix asphalt?

• #### Re: (Score:2)

Hit the deer then it's a 250 deductible and you get road kill. ;)

• #### Re: (Score:2)

Blew \$300 on a new tire last week. Had to swerve so I wouldn't hit a deer, and went straight over a pothole.

\$300 for a tire? Either you drive an 6 figure exotic something, or you are an idiot, or you got fleeced. Or some combination of those.

Oh, and you know you should almost never replace only one tire, right? Both fronts or both rears, unless they are really, really new.
• #### Seems inferior to the current solution. (Score:2, Insightful)

The problem with this is that it won't last. You see they put a cover over it. Why is that? Because goop would get stuck to the tires and that would erode the "fluid" away. So they have to put a cover over it. And the cover might move, or fluid might evaporate or god knows what else.

Consider the current solutions of putting sand in the pothole which works for a little while until the sand is eroded away. You could put a little mat over the sand just like they did in for the fluid to get the same result at a

• #### Re:Seems inferior to the current solution. (Score:5, Informative)

<dadinportland@yah o o .com> on Wednesday April 11, 2012 @05:22PM (#39650441) Homepage Journal

1. Mass TRANSIT is part of the transit budget.

2. There are more then one pothole. There a lot, and the queue is often very long. Plus, if work is going to be done for some other reason, they put off the pot hole repair. And some street required special permissions to close, as well as cost a lot of money in diversions.

3. Depends on your environment, and weather or not the budget allows for quality material and labor.

You need to close off portion of the street, have it located*, check for other work.
That means back ups, delays, store owners angry.

*marked to determine whats under the road at that spot.

• #### Re: (Score:3)

1. Don't loot the road maintenance budget to fund other projects. Next time you want to add a feature, put it on the ballot and tell everyone that taxes are going up to pay for it. And then take ONLY the EXTRA funds collected by the raise to pay for your project. Leave the existing programs alone or you'll starve them and they'll fall appart.

2. The queue is long because you don't fill any of the holes. They sit there for months. If you have so many holes that you leave them there for months then clearly you

• #### Re:Seems inferior to the current solution. (Score:5, Funny)

on Wednesday April 11, 2012 @06:58PM (#39651661)

There's no counter argument to that.

There's always a counter argument.

If you fill the potholes, property values would go up, and with them property taxes. I am firmly against your plan to raise taxes. You must be some sort of democrat.

• #### Re: (Score:2)

By that argument we should spread broken needles around the neighborhood to give the impression of a drug problem... or better yet host crack heads in some homes just to make sure there's a steady supply of dead junkies found naked on park benches to keep the property values low.

• #### Re: (Score:2)

You create jobs in the city. The city saves money. The potholes get filled. Everyone wins.

There's no counter argument to that.

• #### Re: (Score:2)

I got to thinking about this several years go. There are sections of the road that often requires major servicing in high traffic areas. It's a lot of work, I know. But if they could pre-plan construction of the roads like a suspended server room floor, it would be that much easier. Right? Just lift one tile of road, perform work quickly, and lower the tile back down. I'm sure it's a lot more complicated then that with load bearing and all. But I thought the idea sounded pretty nifty if I do say so myself.

• #### Re: (Score:2)

If a section of road is frequently falling apart, that usually means that patch of road just wasn't built robustly enough. E.g. the foundation should have been deeper. That won't stop any potholes, but it is the main issue in some locations.

• #### Re: (Score:2)

In other places, there are underground water flows that degrade the roads. That happens frequently around my area of Pennsylvania. This may also be fixed by laying a deeper foundation; I don't know. Given PennDOT's penchant for half-assing things I wouldn't be surprised if there is an easy fix.

(What's big and yellow and sleeps seven? A PennDOT truck.)

• #### Re: (Score:3)

it's crap like that is that makes Americans want SUVs

And the more bigger, heavier SUV's, the quicker the roads wear out... same with them hybrids, they're a few hundred kilograms heavier than a similar sized non-hybrid car.

• #### Re: (Score:2)

And the more bigger, heavier SUV's, the quicker the roads wear out... same with them hybrids, they're a few hundred kilograms heavier than a similar sized non-hybrid car.

Toyota Yaris - 2295 lbs - 153 inches long
Toyota Corolla - 2800 lbs - 179 inches
Toyota Prius - 3042 lbs - 175 inches
Toyota Camry - 3190 lbs - 189 inches
Toyota RAV4 SUV - 3360 lbs - 181 inches
Toyota Sequoia SUV - 5670 lbs - 205 inches

So the Prius is closest to the Corolla in size, and weighs only about 110 kg more. It's lighter than the Camry and around half the weight of the Sequoia. It's only 2 inches shorter than the RAV4, but the Prius is 140 kg *lighter*. (sorry for mixing metric and non-metric units, b

• #### Re: (Score:2)

Exactly... and it's not the weight that's an issue... it's the possibly an increase in traffic which should be more then countered by a relative increase in gasoline tax revenue, and other road related taxes... the vast majority of which should go to building and maintaining roads. I suspect that increasingly that isn't where the money is going... which is why our roads are resembling post apocalyptic cityscapes.

• #### Re: (Score:2)

I can assure you that the vast majority of the gas tax does in fact go to building and maintaining roads. The problem is that the gas tax is paid per gallon, not per dollar (so that it doesn't rise with inflation) and hasn't been increased in decades. It varies by jurisdiction, but around here we're spending somewhere around half as much as we did 20 or 30 years ago, adjusted for inflation. The fact that materials and construction costs are increasing at a rate considerably faster than general inflation onl

• #### Re: (Score:2)

By that logic you should try to make gas cheaper and thus increase consumption rather then try to choke off consumption.

So... I can only assume you support the keystone pipeline, right? Or do you believe in reducing consumption... thus making the problem worse?

If you go out of your way to make my gas expensive and then want to pile an increasingly higher tax on top of it as I start cutting back... you've got another thing coming.

Stop standing in the way of consumption and then MAYBE you'll have a case if th

• #### Re: (Score:2)

Your specs confirmed my previous post. The Prius, which is slightly smaller than a corolla is 240lbs heavier. The cause is they may have a slightly smaller engine but they also have two electric motors and a rather heavy battery pack to go with it, along with a larger more complex transmission.

SUV's are also heavier than regular cars, as your data shows.

• #### Re: (Score:3)

Oh like cars in the 50s were light? Have you seen what a 1956 Cadillac looks like? It's an all steel boat on wheels. Don't tell me the cars today are too heavy. That's just whining. Yes, cars in the 1980s were lighter then today. They mostly got heavier when the safety standards were changed which required more steel reinforcement. That's like the utilities saying we use too much water or use too much electricity. We use less water per capita then we did 50 years ago and apparently we're still too wasteful

• #### Re: (Score:2)

I have no idea if this story is true, but reportedly old Cadillacs contained a couple hundred pounds of lead weights just to make the ride smoother.

• #### Re: (Score:2)

Gas was so cheap then it didn't matter. Good times.

• #### Re: (Score:3)

Gas was so cheap then it didn't matter. Good times.

Inflation adjusted gas prices in the 1950s seems to be pretty average, and higher than they were in the 1990s.

• #### Re: (Score:2)

Its a problem caused by many factors. Number of vehicles and the impact each vehicle has on the road. Why do you think trucks pay more in road taxes and are charged based on weight? A modern SUV weighs more than a modern sedan, and the sedan is probably safer too.
• #### Re: (Score:2)

Oh like cars in the 50s were light? Have you seen what a 1956 Cadillac looks like? It's an all steel boat on wheels. Don't tell me the cars today are too heavy

The 50s Cadillac weighed the same, but it paid more than twice as much fuel tax, since it was so much less efficient and fuel is taxed per gallon, not per dollar.

• #### Re: (Score:2)

the quicker the roads wear out...

As a engineering rule of thumb, road damage is roughly proportional to the 4th power of axle weight:
http://en.wikipedia.org/wiki/Gross_axle_weight_rating [wikipedia.org]

• #### Re: (Score:2)

So there you go, 10% more weight = 46% more road damage. ( 0.1^4 = 1.46)
So according to the weights of cars in another post, a Prius (mid-sized hybrid) does 140% the damage of a Corolla (mid-sized non-hybrid) and a Sequoia (the big toyota suv) does 1000% the damage of a Camry (the big toyota car).
• #### Re: (Score:2)

Hybrids are more harmful to the road than ordinary cars for the same reason big trucks are, pressure per square inch. And the hybrids have narrow tires so not only is the PSI high but they are more likely to cover less of the pothole and thus cause more side to side buckling. The worst though is probably modern 3/4 or 1 ton trucks with 4x4 and narrow, hard (high-mileage) tires, which have a small contact patch and can easily weigh over 8,000 pounds unloaded.

• #### Re: (Score:2)

I agree they're not hard technically to fix. They are hard logistically. When there's one hole, you have to divert traffic from that lane for a period of time. You then need several pieces of heavy equipment to grind the surrounding road in order to make a rough surface for adhesion, heat and apply the asphalt mix, flatten it into place, and finally replace any damaged road striping. And if that pothole is seen by 100,000 people in a week, that's a lot of cars you inconvenience while doing your fix, so
• #### Re:Seems inferior to the current solution. (Score:5, Interesting)

on Wednesday April 11, 2012 @06:19PM (#39651097)

Not if you do it at night which is the only time you should ever do it.

Grocery stores restock at around 2AM. If they can get 20 guys to show up in a truck every night to unload and restock the shelves in a SINGLE store... I should think the city should be able to fill some god damn pot holes in the wee hours of the night. This is not complicated. It's obvious and easy.

Businesses across the country do disruptive things at night. Most server updates don't happen during business hours. They happen at midnight or 2 am.

If practically every business does this already, why can't the city? And don't give me that it's too many people. Think about how many people it takes to restock every grocery store in the city every night? That workforce ALONE dwarfs what the city would need to take care of pot holes several times over. And bargain grocery stores find the practice entirely economical.

The problem is not the asphalt. The problem is the city, the transit unions, and people that find it acceptable to leave pot holes unfilled for months on end.

• #### Re: (Score:3)

Grocery stores restock at around 2AM. If they can get 20 guys to show up in a truck every night to unload and restock the shelves in a SINGLE store... I should think the city should be able to fill some god damn pot holes in the wee hours of the night.

That's not how it works. The night crew is like five or six people, unless it's a 24 hour store in a busy area. But in a non-busy area even for a whole Safeway store you only need a half-dozen people. A guy shows up and unloads a truck with a pallet jack and the midnight down crew breaks down the shipment and stocks and faces the shelves.

• #### Re: (Score:2)

THIS is why pot holes are so annoying. It's not because they're hard to fix. It's because they're stupid easy to fix and they're not because the transit authority is lazy.

No, no they aren't easy to fix. They're very difficult to fix, because water keeps getting back in there. The only really good way to fix them is to repave the section.

• #### Re: (Score:2)

How does water get into gravel bound together by tar?

And in any case, I have no doubt that the spot probably wears differently then the rest of the road. So what? So you have to retouch it every year or so.

If the logistics of keeping the road flat are too much for the transit authority to handle then they should delegate the task to someone more competent.

• #### Re: (Score:2)

Sometimes...just sometimes, I wish those of us who actually like mass transit were as big of a------s about all the money "wasted on roads that only a few people use" as guys like you are about mass transit. Maintaining the estimated 4 million miles of road in the US is not free. That costs real money. Real money that is always massively. subsidized to rural areas by urban areas.

it's crap like that is that makes Americans want SUVs. The urban street is increasing turning into an off road experience between the god damn speed bumps and the god damn potholes. Try this guys... flat. Just try it.

[cough, cough]bull[cough, cough]it. American's wants SUVs because 1) they like complaining about "high gas prices" 2) they live so

• #### Re: (Score:2)

As to subsidies... I don't have a problem with that. Just do the work and don't divert funds. If I'm paying gas taxes that should go to roads. If I'm paying bus fare that should go to the bus. Never the twain should meet. If you want to stack additional tax money on either side, then go for it. But the gas tax should be reserved exclusively for road maintenance.

Something that bothers me is when money intended for one program is used to pay for something else. Especially since politicians will often campaign

• #### inverse problem (Score:4, Insightful)

on Wednesday April 11, 2012 @05:41PM (#39650613)

Instead of allowing people on highways to drive faster w/o damaging their cars, why not deploy them to cause damage to cars that are driving too fast.

Maybe this stuff can be used as a movable speed bumps in school zones and children play zones? If you drive slow enough, no problem. If you run over them too fast, you destroy your car's suspension. People are pointing out that it can be stolen, perhaps this mobility is just what you need for this problem. In the middle of the day (or the weekend), you can just move them away. That seems like this would be much more effective than the radar speed-signs that exist there now and less of a liability and expense for hiring lots of crossing guards. You might also sell this to HOAs that can't convince local fire departments to allow them to put in speed bumps or neighborhood groups that have lots of children playing in their front yards.

Dibs on the patent for this use case. ;^)

• #### Why fix the roads? (Score:2)

Where does it say that the local government has to fix roads? Or even MAKE roads?

• #### Re: (Score:2)

Is that you, Ron?

• #### Asphalt is Non-Newtonian (Score:2)

Plus what the heck are we going to do with all of the asphalt?

• #### "Non-Newtonian" =/= shear-thickening (Score:5, Informative)

on Wednesday April 11, 2012 @06:01PM (#39650863)

I'm getting fed up of the constant references to the magical properties on "non-Newtonian" fluids. Non-Newtonian fluids have a huge range of properties in terms of their response to shear and change over time. This is constantly abused by geeks who should know better. Off the top of my head:

What people usually mean is a "shear-thickening" fluid such as corn starch and water. These become more effectively viscous in response to shear.

"Shear-thinning" fluids are *also* non-Newtonian, are fairly common, and have the exact opposite behaviour. Ketchup is a great example - shaking the bottle helps it flow more easily.

Another interesting case are Bingham plastics - these have a yield stress before they will flow. The classic example is toothpaste - it will stay as a lump on the bristles under its own weight, but spreads easily enough under pressure.

So the next time somebody wants to demonstrate non-Newtonian properties on their speaker cone, pass the ketchup!

• #### Re: (Score:3)

Precisely. I was just chatting with the paving crew working out in front of my house about how they handled the various possible solutions for the viscous stress tensor.

• #### Re: (Score:2)

I'd imagine they were "using concrete" rather than "using a solid"?

Actually, what with the graduate employment situation it probably won't be long before paving crews *do* have mechanical engineering degrees

• #### Re: (Score:3)

I'm getting fed up of the constant references to the magical properties on "non-Newtonian" fluids. Non-Newtonian fluids have a huge range of properties in terms of their response to shear and change over time. This is constantly abused by geeks who should know better. Off the top of my head:

What people usually mean is a "shear-thickening" fluid such as corn starch and water. These become more effectively viscous in response to shear.

"Shear-thinning" fluids are *also* non-Newtonian, are fairly common, and have the exact opposite behaviour.

So you recognize that others are using the term "non-newtonian fluid" in a technically correct fashion, but you are frustrated by the fact that they do so without using more specific terminology? Furthermore, their choice of words amounts to some kind of abuse?

Come off it, really. Yes, you know more about the subject than others do--good for you. That you feel it necessary to speak out as you have only reveals the height of your hubris and the depth of your snobbery.

Most people will never have a need

• #### Another fun use (Score:2)

Slightly OT, but another fun use for these fluids is to fill a shallow container with one and place it above an upward-facing speaker. Hook up a tone generator and you can watch the fluid form increasingly intricate patterns as the frequency of the tone is increased.

Stoners, take note!

• #### It's not the fluid that makes this idea (Score:2)

It's the bag! You could put most anything in it and it'd work. Although you couldn't patent putting gravel in a bag.... or could you?

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