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A strange water stain: an "eye of Sauron" in my living room?

published: 23/02/18, 13:00
by Christophe
I had a rather strange water stain (snow residue) :) in my living room this week. Bigre I have an eye of Sauron in my living room? : Cheesy:

Nature is beautiful (when you pay attention to it)! But how can this phenomenon be explained?

Surely to do with the surface tension and / or a very particular geometry of the water drop (precise volume so that it becomes a "perfect" dome / gravity / water viscosity / soil friction ... ) but can this explain the triple crown? The floor is in MDF type laminate ...

If we can't find any explanations, will we call the Vatican? : Mrgreen: : Mrgreen:

The total diameter of the puddle is about 30 mm ... I did not measure the height (within 5 mm I would say)

Eye_tache.jpg


It dried "as is" but was slightly damaged:

Eye_tache_sec.jpg

Re: A strange water stain: an "eye of Sauron" in my living room?

published: 23/02/18, 13:33
by thibr
is there perhaps also a link with the relief and the undulations when the drop hits the ground?

Re: A strange water stain: an "eye of Sauron" in my living room?

published: 23/02/18, 14:56
by Christophe
In this case it is not a drop of water that fell (which would have been a sacred drop since the spot is 30 mm in diameter : Cheesy: ) but snow that I had stuck on the shoes (hence the dirt also in the water)

Re: A strange water stain: an "eye of Sauron" in my living room?

published: 23/02/18, 15:56
by sen-no-sen
Nice phenomenon of self-organization!
I don't know if it's the eye of Sauron but it falls into the domain of the pareidolies *.


*A pareidolia is a kind of optical illusion which consists in associating a shapeless and ambiguous visual stimulus with a clear and identifiable element, often a human or animal form.
https://fr.wikipedia.org/wiki/Par%C3%A9idolie

Re: A strange water stain: an "eye of Sauron" in my living room?

published: 23/02/18, 16:23
by Christophe
It is certainly not the eye of Sauron since he is reptilian! But maybe a cousin! : Cheesy: : Cheesy: : Cheesy:

Ok to classify this into pareidolia but this does not explain how it was formed ...

Re: A strange water stain: an "eye of Sauron" in my living room?

published: 23/02/18, 17:03
by sen-no-sen
Christophe wrote:It is certainly not the eye of Sauron since he is reptilian! But maybe a cousin! : Cheesy: : Cheesy: : Cheesy:

Ok to classify this into pareidolia but this does not explain how it was formed ...


As you rightly noted, this phenomenon is certainly linked to the reigning tensions in the drop of water.
The water seems liquid, but it suffices to observe an ants drinking (or eating?) A drop to understand that this one behaves on a small scale like a kind of molasses.

Image

In the case of your puddle, we see that the iris is formed in the 2/3 zone starting from the center, ie in the zone where the water is the thickest.
The tension ratio between the dust and the body of water should favor their distribution within the puddle.

Re: A strange water stain: an "eye of Sauron" in my living room?

published: 23/02/18, 22:32
by Christophe
sen-no-sen wrote:In the case of your puddle, we see that the iris is formed in the 2/3 zone starting from the center, ie in the zone where the water is the thickest.
The tension ratio between the dust and the body of water should favor their distribution within the puddle.


Ok but how to explain the triple crown? Dust of different sizes?

Re: A strange water stain: an "eye of Sauron" in my living room?

published: 23/02/18, 23:33
by sen-no-sen
Christophe wrote:Ok but how to explain the triple crown? Dust of different sizes?


Probably.
The distribution of the dust being distributed as a function of the surface tensions in the different areas of the puddle.
Seen from the front, the puddle forms a sort of flattened dome, it is very probably the curvature of this one that generated the distribution of the dust.

Image
Drop of liquid placed on a solid surface at an equilibrium contact angle θe.
When γsv> γsl + γ, the surface is said to be of high energy and the liquid tends to spread over it. In this case, we speak of a wetting or hydrophilic surface. The contact angle is less than 90◦. In the case where θ = 0◦, the wetting is total.


Image
Drop flattened on the solid surface, θ = 0◦, in case of total wetting.
Conversely, if γsl> γsv + γ, the liquid tends to form small droplets whose contact angles are much larger and greater than 90◦. The wetting in this case is partial. In order to determine whether or not a drop will spread on a substrate, it is necessary to consider the spreading parameter S which represents the energy difference between a dry and wet substrate. This parameter is defined by the following relation:
S = γsv - (γsl + γ)

To know more:http://physique.unice.fr/sem6/2014-2015/PagesWeb/PT/Rigidite/tension.html