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Not really a full answer for you, but one thing that this page clarified for me:

I had generally previously thought of viscosity as "how slow" a fluid is. High viscosity means high "thickness," which means it flows slowly (like molasses vs. water).

But as presented on this page, viscosity is actually a measure of "how fast" — how fast the effects on one molecule can spread out from there to neighboring molecules. Perhaps you could think of sounds waves moving through a substance — a "thick" substance like solid metal propagates those waves quickly (on a molecular level), while with a "thin" substance like air it's much slower. In the more precise language from the article: "viscosity controls the diffusion of momentum..."

So, because this diffusion happens quickly in a high-viscosity situation, little whorls of turbulence are inhibited, because the forces governing those whorls get spread out/diffused quickly.

Perhaps you missed the part of the article talking about diffusion, or did not see the connection? The link between that and viscosity was not immediately apparent to me, either.




Thank you, this feels helpful.

Though I don't think I missed a part of the article, I feel more like the author did ;)

What I still don't get is what the difference between high and low viscosity looks like on a particle level. I don't understand why he introduced the collision between two molecules and then never explained that.. :)




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