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Solar Moat Motion

a bit of current helps keep your moat from going stagnant
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One problem that crops up when you're trying to design a moat for your house is mosquitoes: see, they like to lay their eggs in stagnant water. Gross mechanical pumping solutions are an option, but they require maintenance; likewise a bit of chemical warfare isn't that healthy for the environment. So what can you do ?

Simply shape the bottom of your moat to be a series of parallel sawtooth cross-sectional ridges. Paint the diagonal of the "teeth" black and the vertical white.

When the sun heats up the black portion of the ridge the adjacent water will be heated and will not only move upwards, but will also move forwards.

Moat: view from above; note the ridges
___________________
|||||||||||||||||
---------------------------

view from the side (stretch it out horizontally for a better picture)

/|/|/|/|

As a bonus, this method will allow you to drop model ships into the moat and have them sail around the house... perhaps even a small raft.

FlyingToaster, Jan 04 2009

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       I'm not certain that the water will in fact develop any real current. Heated water has no reason to move perpendicularly away from the heated surface, it should attempt to rise straight up.

You might manage something with slanted clear layer and a dark surface:
/ / / /
--------
That way the light passes through the clear layer, heats the bottom, which then rises up and is directed to the side (right in this case) by the clear layer.
Having alternating slanting layers and shading above the moat might also work:
  

       / \ / \ / \ / \ / \
-------------------- That way the heated water is directed into the shaded area, cooled there, and directed into the next heated area as it sinks.
Of course, you've got to make sure things like neighbors, animals, barbarian hordes can't cross over the shades.
MechE, Jan 04 2009
  

       I'm thinking that an inverted black funnel shape held suspended inches above the bottom with the center stack terminating inches below the surface should cycle the water nicely. Might even get a little fountain effect. (+)   

       those could work; my idea was that the water on the diagonals would be heated, attempt to rise and move forwards(ie: to the right in the diagram, note that the diagonal I imagine is much less vertical than ASCII permits to draw simply.... more like this minus the bumpies
  

       ..--~~^^i..--~~^^i..--~~^^i   

       or   

       .-~^i.-~^i.-~^i
FlyingToaster, Jan 04 2009
  

       I don't know though [MechE]'s methods sound better, both are unlikely. Water is phenomenal at normalizing temperature gradients so applying these methods that might work in air are unlikely to work with water. Better to do PE panels and some elec motors and propellers. Make sure the path lacks corners and after a while it may get a current.. Maybe it could work as inefficient energy storage also.   

       PS Some fish or a couple of drops of oil will also solve the mosquito problem.
MisterQED, Jan 04 2009
  


 

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