TITLE: What's the reason behind such a strange motion of floating particles in stationary water?
QUESTION [4 upvotes]: Well one day I noticed something really strange about the motion of floating particles in "stationary water" (in the first video the water was stationary).
(Actually the particles might not be much visible but you need to focus in the middle and  about the turning and I guess you will catch them.)
Here's the video (Youtube, 11 seconds) or try this one.

Let me explain what is happening in the video :
Actually the particles in the middle of the horizontal water channel  are flowing in one direction (say $+x$ direction)  and the particles near both the edges of the channel are flowing in the opposite direction ($-x$ direction) which is very strange.
So Are the molecules of water showing "such" kind of motion ? Or Are the particles doing it themselves and the water is stationary ? I would like to add that their was no macroscopic flow of water.
My question is that why are we getting such a two directional motion ?
Extra informations: I don't know what the particles in the video are because the water in that video was the water left after some rain shower. But you could try the same experiment with any powder ( actually my friend did it. He took a container and made its surface wet. And then he added some powder and tried tilting the container. The particle in the middle of the channel followed the incline but around both the edges they climbed up the incline).
Another video (my friend's video) showing the same effect :
Check this out (Youtube, 20 seconds)

REPLY [0 votes]: The thickness of water on a surface depends on the cohesive force.
When the overall flow of the water is stationary its upper surface is still moving due to the reminiscence  of the initial force ( responsible for flow, i.e gravity in this case).
However, this remaining flow is not sufficient to exceed the cohesive force holding it together at the  boundary.
Hence, the flow of water ( particles on the water) at the volume region has to return from the flow in the surface region to keep the thickness of the water same.
However, when tilted the gravity's force exceeds the cohesive force making the overall water flow again.
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