non-newtonian fluids...

[Joy]

I bet most of you know what a Non-Newtonian fluid is but for those who don't, a Non-Newtonian fluid is something that acts like a solid under pressure but other wise acts as a liquid.

 

Here is one simple way to make a Non-Newtonian fluid:

 

2 parts corn starch

1 part water

 

The thing is, that with this set of materials the product ends up being milky white in hue.

 

My question is if any one knows how to make a see thru/translucent Non-Newtonian fluid? I would like to be able to make look as water-like as possible:cool:

[John Cuthber]

Well, I think I know what a non Newtonian fluid is and I don't think you are right about it.

http://en.wikipedia.org/wiki/Non-Newtonian_fluid

There are plenty of thixotropic varnishes on the market, I don't know if they are clear before they dry.

You might be able to find a dilatant mixture of a solid and liquid (that behaves like cornstarch and water) where the 2 components have the same refractive index. Even then you will have problems because the optical dispersions of the 2 materials are likely to differ. I might try powdered glass in glycerine if I were looking for such a mixture.

[Klaynos]

Blood's non-newtonian isn't it?

[Joy]

wiki is not a site worth looking at, any one can edit it to say what ever they would like it to say:doh:

do you have any thing better to site?

[John Cuthber]

I know that wiki is not always reliable but, in this case, it is correct. Why bother to raise the matter of wiki's editabillity? it doesn't make any difference to the error you made in the first place.

[insane_alien]

just because anyone can edit it doesn't mean that it is wrong about everything.

 

wasn't there a study that put wikipedia and britannica roughly around the same for accuracy levels.

[Klaynos]

just because anyone can edit it doesn't mean that it is wrong about everything.

 

wasn't there a study that put wikipedia and britannica roughly around the same for accuracy levels.

 

wp was a bit wronger than britannica on average, but has FAR FAR more articles... And corrections are made faster IIRC

[Joy]

but i was right

 

"property of this non-Newtonian fluid becomes apparent. The application of force - for example by stabbing the surface with a finger, or rapidly inverting the container holding it - leads to the fluid behaving like a solid rather than a liquid. More gentle treatment, such as slowly inserting a spoon, will leave it in its liquid state."

-wiki

 

is that or is that not what i said

 

http://en.wikipedia.org/wiki/Non-Newtonian_fluid

[whatsitsface]

Gels are usually translucent and often quite transparent and they are non-Newtonian liquids.

[John Cuthber]

Joy,

Do you understand that there is a difference between "poodles are dogs" and "dogs are poodles"?

 

Similarly, there is a difference between "liquids that acts like a solid under pressure are non newtonian" and

"non newtonian liquids acts like a solid under pressure ".

 

Since the second of these is what you said, but the first of them is true I still think you were wrong.

[insane_alien]

i agree with john here. you are describing one type of non-newtonian fluid but it by no means includes all of them. there are some where it is the opposite effect and they get thinner under shear stress instead of thicker.

[Joy]

ok what ever you all missed the point

 

MY Question was:

"if any one knows how to make a see thru/translucent Non-Newtonian fluid [that acts like a solid under pressure but other wise acts as a liquid]? I would like to be able to make look as water-like as possible"

 

i don't really care about the other types of Non-Newtonian fluids as they will not help for what i am trying to do...

[John Cuthber]

I think you may find I didn't so much miss the point as give you a possible answer,

Since you seem to have missed the point, here it is again.

"You might be able to find a dilatant mixture of a solid and liquid (that behaves like cornstarch and water) where the 2 components have the same refractive index. Even then you will have problems because the optical dispersions of the 2 materials are likely to differ. I might try powdered glass in glycerine if I were looking for such a mixture."

 

Just for the record our collective psychcic abillities are somewhat limited so, since you didn't tell us what you wanted it for, we might not have been able to read your mind and find out.

[Sisyphus]

wiki is not a site worth looking at, any one can edit it to say what ever they would like it to say:doh:

do you have any thing better to site?

 

Yet you ask on a forum in which anyone can answer.

[John Cuthber]

There are, no doubt, many errors in wiki. So what? The page about non-newtonian fluids was correct when I saw it. Nobody has actually said it's wrong.

[Klaynos]

So, I started a module on fluid mechanics yesterday and one non-newtonian fluid that took me slightly by surprise, I suppose due to never thinking about it was milk...

[insane_alien]

So, I started a module on fluid mechanics yesterday and one non-newtonian fluid that took me slightly by surprise, I suppose due to never thinking about it was milk...

 

along, with yoghurt, jam, butter(yeah, butter), paint, any type of spread, glue, ketchup, tomato soup(well, any soup with a thickening agent) the list goes on and on.

[Klaynos]

Yes indeed, milk just struck me as slightly odd...

[insane_alien]

i think it is mainly because it is a colloidal mixture rather than just the normal liquid-liquid mixture.

[uwmengineer]

from milk to butter...

that must be an example of shear-thickening non-newtonian fluid?

[insane_alien]

nope, milk to butter is a chemical change. nothing to do with fluid properties.

 

though both are non newtonian in nature. butter is shear-thinning by the way, thats why you can spread it.

[Legendary]

This would be like a shear thickening fluid(STF) right?? They say if you mix some Colloidal silica and this liquid called Polyethylene Glycol you can achieve what your trying to make. I really don't know the type of Silica used and the reat of the real chemicials used ,but I heard these are the key components. I myself have been wondering what is the complete checmicials used in making a (STF).

[valentine_18h]

A question:

In cone and plate viscometer, shear rate is calculated from:

y=u/tan(x)

 

where y is the shear rate and u is the angular velocity.

and in parallel plate viscometer,shear rate is calculated from:

y=ur/h

Can anybody derive these two relationships? thnx