Capillary pump ?

[Externet]

Good day.

On top of a garden window I have, rain puddles on top and I placed a rag strip hanging over the edge.  Works good; it wicks and drips to the point of emptying the puddle dry. Sort of a wick siphon.  [ Image 1 below ]

Can a wick pump water high within reason, to the point T and dripping at a lower wick point E well above the surface S ?  [ image 2 above ] 

What are the limits ?  Wick capillary properties ?  Has anyone done it ?  Is there a convenient type of wick material that is recommended/optimal for higher reach ?

[exchemist]

On 1/16/2025 at 4:26 PM, Externet said:

Good day.

On top of a garden window I have, rain puddles on top and I placed a rag strip hanging over the edge.  Works good; it wicks and drips to the point of emptying the puddle dry. Sort of a wick siphon.  [ Image 1 below ]

Can a wick pump water high within reason, to the point T and dripping at a lower wick point E well above the surface S ?  [ image 2 above ] 

What are the limits ?  Wick capillary properties ?  Has anyone done it ?  Is there a convenient type of wick material that is recommended/optimal for higher reach ?

No. It can act as a siphon, but it can’t pump uphill. Conservation of energy tells you that. Capillary rise, or wicking,  is due to attraction of water molecules to the surface of the glass or wick material. Clearly, once the top of the tube or wick is reached, there is no more upward attraction. So nothing can come out at the top. 

[Externet]

Thank you.  The submerged rag end in image 1 then rises 3cm over the water surface to the edge soaking all its length and drips-over at the lower end.  

[exchemist]

5 hours ago, Externet said:

Thank you.  The submerged rag end in image 1 then rises 3cm over the water surface to the edge soaking all its length and drips-over at the lower end.  

Exactly. The edge is lower than the level of liquid, so it is acting like a siphon, in which the reduction in gravitational potential energy drives it. 

I first noticed this effect eating shredded wheat breakfast cereal, observing that milk dribbled out of the spoon if any shreds of cereal dangled over the edge. The entire spoon could empty itself of milk, even though I was holding it perfectly level. 

All because of surface tension. 

Edited yesterday at 07:26 AM by exchemist