More quizzage

[outragous76]

If you spill a 100L drum  of diesel on a road surface - how much area of road would you expect to become wetted by the liquid? (assume dry road and relatively flat (<1% gradient) surface)?

what would be the effect on a sloping surface? (5% gradient in 1 direction)


There are motives behind this question and I do not have an answer

[tikay]

I would suggest the predominate factor is now how far it would spill naturally, but other vehicles running over the spilt liquid, which would then spread the diesel over a considerable distance (length) via their tyres, quite apart from "splashage" which would spread it laterally.

Pure guesswork, but the road surface could be damaged over a 200 or 300 yard length.

The insurance bill, of course, would be quite something......

[millidonk]

Also depends on weather conditions, condition of road, type of road etc

100 litres = 0.1 cubic metres or 3.5ish cubic feet is it one of those trick questions like that oil will not move on a flat surface?

in short IDFK and i wouldn't really know where to start, surely 5% in 1 direction would go for a while

[outragous76]

You can assume no traffic movement, let's say there is an imaginary lorry on its side blocking the road

Surface is macadam

I guess on the basis of simple dispersion how far might we expect? Let's say it is a 100l drum which tipped over in 1 location and diesel was pouring out of a spout (ie no huge gush) and we expect all 100l to spill (no retention in container)

[outragous76]

Oh and if we could stay metric, particularly in square numbers that would be nice

[outragous76]

Not a trick question, I use diesel as petrol would evaporate. I am genuinely interested in how people see the answer and their reasoned logic.

[kinboshi]

"The authors review the wetting and spreading properties of simple liquids on solid surfaces, putting emphasis on the role of the heterogeneities of the solid surface and on the spreading kinetics. In a situation of partial wetting, the liquid does not spread completely and shows a finite contact angle on a solid surface. The partial wetting behaviour on perfect solid surfaces is well described by classical capillarity. Heterogeneities of the solid surface lead to contact angle hysteresis. In a complete wetting situation, the liquid forms a film on a solid surface with a thickness in the mesoscopic range. The direct long range interaction between liquid and solid described by the so-called disjoining pressure governs the physics of these films. Films of mesoscopic thickness also appear in the spreading kinetics of liquids. These precursor films form ahead of macroscopic advancing liquid fronts. The spreading kinetics is extremely slow. "

(http://iopscience.iop.org/0034-4885/55/4/001)

What he said (probably).

My answer:

Things like temperature will affect the spread as the viscosity of the diesel will change.  But as a total guess, if the road is assumed to be totally flat, I reckon the 'puddle' eventually formed would be about 1cm deep (on average, maybe slightly deeper in the middle and shallower towards the edges.

If it's 1cm deep, and 100l = 100,000cc so a circle with a radius of about 180cm.

[Skippy]

Did you ever do that experiment at school with cooking oil floating on a bath of water? What you do is you drop a very small drop of oil onto a bath of water. You estimate how much oil you dropped onto the bath.

E.g. http://www.practicalphysics.org/go/Experiment_633.html

The key point is that the oil slick spreads out until the oil is 1 molecule thick. Because you know roughly how much oil you dropped in, and how big the resulting slick is (see the link for how you do this) you can estimate the size of an oil molecule.

Back to the problem at hand,I think Boshi's nailed it, except that I think a 1cm thick slick is a massive overestimate. If you've ever dropped some cooking oil on your kitchen floor, you'll know it takes up a huge area. 100L is a lot of liquid.

[outragous76]

So in Boshi's Eg, what area does it cover at 1mm thick?

[millidonk]

So in Boshi's Eg, what area does it cover at 1mm thick?

circle with diam of 180metres?

[kinboshi]

Did you ever do that experiment at school with cooking oil floating on a bath of water? What you do is you drop a very small drop of oil onto a bath of water. You estimate how much oil you dropped onto the bath.

E.g. http://www.practicalphysics.org/go/Experiment_633.html

The key point is that the oil slick spreads out until the oil is 1 molecule thick. Because you know roughly how much oil you dropped in, and how big the resulting slick is (see the link for how you do this) you can estimate the size of an oil molecule.

Back to the problem at hand,I think Boshi's nailed it, except that I think a 1cm thick slick is a massive overestimate. If you've ever dropped some cooking oil on your kitchen floor, you'll know it takes up a huge area. 100L is a lot of liquid.

Depends on the road surface.  'Wetting' needs to be taken into account:  http://en.wikipedia.org/wiki/Wetting and also consider the tarmac surface on a 'zoomed-in' scale.  It's a pitted surface with lots of craters and valleys that will hold the diesel as well as the diesel that sits above the tarmac.  Maybe 1cm is too much, and maybe 5mm is more accurate?

If it's 5mm deep, then the diesel will cover twice the surface area to a 10mm deep puddle, so the radius would be: about 250cm.  If it's 1mm deep then it'll cover ten times the surface area, so a circle with a radius of about 565cm.

[GreekStein]

i prefer picture quizzes

[millidonk]

i prefer picture quizzes

[ManuelsMum]

The surface type will affect capillary action.

[outragous76]

The surface type will affect capillary action.

its macadam and like kinbo said it is both textured and porous