Strange water and air behavior

[Cherryman]

Strange water and air behavior


Anyone know what is happening here?
I've got bubbles rising up in the tube with an airpump, taking along a water flow from beneath.
But at the side of the pipe a strange effect occurs, spontaneous bubbles going sideways and disappear again.
The pipe does not leak!  And bubbles going sideways. 
Also there is no swirling or a vortex.. 


Any suggestions?


Might there be a potential difference which creates bubbles?


http://youtu.be/dC2TgYB3YRI

[MarkE]

The moving bubbles inside the tube can develop a charge on the tube ID.  Are you using ordinary tap water, or distilled water?  If this is being caused by charge, then I expect the effect will decrease if you add a little table salt to the water.

[Cherryman]

The moving bubbles inside the tube can develop a charge on the tube ID.  Are you using ordinary tap water, or distilled water?  If this is being caused by charge, then I expect the effect will decrease if you add a little table salt to the water.

Tnx for reply.


Yes it is tap water with a little vinegar, to desolve any chalk residue as I bought the thing second handed.


It is strange to see, as they do not care going up, just sideways and disappear.
There is no electrical device near, the air pump is way of, only a Led light on top.


I will try the salt later, after cleaning this one out.


Nice effect though!

[MarkE]

As the air bubbles move against the ID of the plastic tube they can separate charge from the surface, leaving the tube charged relative to the surrounding water.  If the water is fairly pure then it conducts poorly.  Tiny bubbles in the water get attracted to the OD of the tube, where they charge and get repelled.  I suspect that the reason the bubbles that are big enough to see are the ones moving away from the tube is due to surface tension.  Adding salt to the water to make it more conductive should reduce the charge build-up.  You can then try it with distilled water where if I am correct, the effect will be more pronounced.