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| Viscosity - a question with pur'Poise' ? |
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| picclock:
I'm trying to estimate flow rates of two different liquids through a system. This is just flow under gravity. Would I be correct in thinking that the ratio of flows through an identical system will be the same as the viscosity ratio of the two liquids ? I'm afraid that all I know about viscosities is that it was measured in Poises and I seem to recall that it was a value based on time it took for a funnel to empty - which, if memory serves, would be a pretty good analogue. Many thanks for your time Best Regards picclock |
| andyf:
It's probably more complicated than the flow rate varying simply in proportion to the viscosity. If you're like me, you'll be none the wiser for doing so, but have a look at this for flow through a pipe: http://en.wikipedia.org/wiki/Hagen%E2%80%93Poiseuille_equation and this seems to deal with flow through a narrow orifice: http://www.mcnallyinstitute.com/13-html/13-12.htm Andy |
| picclock:
Hi Andyf I've been over those equations and they are not nice :doh:. After I posted the question, I thought I could easily prove it myself by using the flow rate of water and then kerosene through a small pipe. If the viscosity ratios are close match to the ratio of flows then that's likely good enough. Many thanks for your time picclock |
| John Rudd:
Hmm..just seen this.... Fluid flow through a pipe is influenced by the Reynolds number of the fluid or the gas passing through from my college days when we did Bernoulli's theorem for flow calcs... Yuck..I hated it..made my brain hurt... :bang: |
| andyf:
Your college studies would be a great deal more help with problems like this than mine, John, which were law. Still, at least I avoided any troublesome sums :coffee: Picclock, I'm sure you are right - measuring jugs and a stopwatch look like being the easiest way. There's a bit table here http://www.engineeringtoolbox.com/absolute-viscosity-liquids-d_1259.html which to me seems to say that kerosene is about half as viscous as water. That's if I understand the units correctly (which I probably don't!). Andyu |
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