
A Tesla Valve - stazz1
https://en.wikipedia.org/wiki/Tesla_valve
======
ObsoleteNerd
I’m assuming this is being posted due to this recent popular video, which I
think is a very well made demonstration of how the valve works:

[https://www.youtube.com/watch?v=tcV1EYSUQME](https://www.youtube.com/watch?v=tcV1EYSUQME)

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ladberg
While this is a very cool video, I don't think it demonstrates a Tesla valve
that well. In this example, the flame moving isn't really the same thing as a
fluid moving with the exception of the gas expansion within the tube that he
mentions.

Instead, the flame basically does a BFS (to put it in programmer terms) of the
tube instead of actually moving the fluid through the tube. It just also works
out that the gas expanding pushes it in the right direction due to the design
of the valve.

~~~
yellow_lead
I agree and I don't see why he couldn't have just used a smoke bomb. I don't
see the big difficulty of demonstrating this valve like he mentions at the
beginning.

~~~
ulrikrasmussen
It would work with fluids also, wouldn't it? It would be cool to watch it
submerged in a clear fluid, with a colored fluid forced through in one end.

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josephg
This is really clever, but I bet there's all sorts of wacky ways that a 3d
version of this could be optimized.

It would be really interesting to throw this design into a learning algorithm
with an attached fluid simulation to estimate effectiveness. I wonder if
anyone's done this. What learning algorithm would be most effective? And I'd
love to see what a learning algorithm would come up with. I suspect an
optimized version of this would be really organic looking and have lots of
weird spirals and things in non-obvious ways.

~~~
pstuart
Akin to this:
[https://en.wikipedia.org/wiki/Evolved_antenna](https://en.wikipedia.org/wiki/Evolved_antenna)

~~~
kossTKR
And that in turn reminds me of the obscure zig-zaggy convoluted shapes in
molecular biology:
[https://www.youtube.com/watch?v=B_zD3NxSsD8](https://www.youtube.com/watch?v=B_zD3NxSsD8)

These are also born out of an evolutionary optimisation process, and probably
has a form that is intrinsically linked to its function - we just haven't
remotely uncovered yet.

Continuing this line of thought and i am reminded of steganography, hiding
complexity in simplicity or objects with several functions. Also encoding by
moving things in relation to each other and the mysterious field of emergence.
Especially in biology where complexity or patterns can emerge seemingly from
nowhere and hide properties that has to do with relations between points
instead of the points themselves.

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stazz1
Notable Quotes:

Let the future tell the truth and evaluate each one according to his work and
accomplishments. The present is theirs; the future, for which I really worked,
is mine.

Money does not represent such a value as men have placed upon it. All my money
has been invested into experiments with which I have made new discoveries
enabling mankind to have a little easier life.

[https://en.wikiquote.org/wiki/Nikola_Tesla](https://en.wikiquote.org/wiki/Nikola_Tesla)

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doh
First time I discovered Tesla's Valve through this post back in 2013 [0].
Author did some extensive testing on its functionality and made some
interesting comments/observations about old patents. Highly recommended.

[0] [https://fluidpowerjournal.com/teslas-
conduit/](https://fluidpowerjournal.com/teslas-conduit/)

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8bitsrule
This 2000 PhD thesis: [http://www.microplumbers.com/pubs/BardellRL-
PhDDissertation....](http://www.microplumbers.com/pubs/BardellRL-
PhDDissertation.pdf)

gets into the details (including the math). It also thoroughly defines
'diodicity' (not in wiki or some online dictionaries). I'm wondering if Tesla
thought of this while thinking about the operation of diode tubes, and perhaps
the idea of electricity as a fluid.

Diode: Fleming valve, 1904.
[https://en.wikipedia.org/wiki/Fleming_valve](https://en.wikipedia.org/wiki/Fleming_valve)

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etcet
Here's a video showing a microfluidic version of the valve made using shrinky
dinks:
[https://www.youtube.com/watch?v=eNBg_1GPuH0&t=9m15s](https://www.youtube.com/watch?v=eNBg_1GPuH0&t=9m15s)

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soapboxrocket
So I have one of these in my office. I 3d printed it and tested it. It doesn't
really work, but it does give you an interesting flow curve.

~~~
brk
IANAFDE (I am not a fluid dynamics engineer).

My gut tells me that for this to work as designed, you would need to ensure
the fluid moves exactly as intended, primarily smoothly and evenly. I know
nothing about your 3D printer, but if the output is like most I have seen
(even high-end ones), I wonder if the surface aberrations in most 3D-printed
objects would be enough to impact the fluid flow such that it would be
turbulent enough to overcome the intended friction of the channels?

If I had the time, I'd make up a 3D model of this that I could cut on my CNC
machine out of a block of aluminum or hard plastic to test.

~~~
serf
from playing with 3d printed tesla valves , I think that you're right that
surface distortions hinder correct flow.

The way that I created a 3d printed tesla valve _that worked_ was by messing
with overall scale. Bigger works better, until suddenly it doesn't work at
all.

The idea I had previously about why scale may help was the idea that the scale
is gradually turning down the amount that the flow error affects the entire
system until eventually the mass of the fluid induces more 'error' into the
system until the whole thing destabilizes.

In other words : with 3d printed tesla valves it's vital to find the sweet
scale spot between surface-level distortion causing chaos when the valve
itself is too small and liquid mass causing chaos when the valve is too big.

That margin between chaos and stability may be made wider by using a finer
manufacturing technique, like milling or even SLA/SLS versus FDM. I bet that'd
give a wider range of usable sizes.

all that said : even professionally made tesla valves must be made with
certain scale constraints in mind. I believe those constraints are first-and-
foremost a property of the liquid that's going to be transported.

~~~
jakobegger
I'm pretty impressed what you figured out by just experimenting.

What you are describing is the transition between laminar flow and turbulent
flow. The point where this transition occurs is governed by the "Reynolds
Number". As you correctly discovered, the Reynolds number is influenced by
scale and fluid properties (viscosity and density).

The final missing piece is the speed of the fluid, which explains your
observation: "Bigger works better, until suddenly it doesn't work at all."

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Animats
Another useful device in that class is the static mixer. A static mixer splits
up a fluid flow into several parts and reassembles them in a different
arrangement. Multiple stages mix fluids, using less energy than stirring,
especially for high-viscosity materials.

~~~
function_seven
Like the nozzles that attach to those 2-part epoxy syringes? With the “stair
steps” inside forcing the A and B components to mix?

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jacquesm
Would it be possible to create a pump by just having two of these (or even
just one!) and a moving membrane? That would have some interesting
applications.

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btrettel
Yes, typical piston pumps have two check valves.

[https://en.wikipedia.org/wiki/Check_valve#Pumps](https://en.wikipedia.org/wiki/Check_valve#Pumps)

~~~
petermcneeley
I can do you one better.
[https://en.m.wikipedia.org/wiki/Tesla_turbine](https://en.m.wikipedia.org/wiki/Tesla_turbine)

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phkahler
I have often wondered if a jet engine can be made with a fixed cavity of some
sort and no moving parts. One problem seemed to be combustion pushing gasses
equally to the exit and inlet. This may be the piece I have been looking for
to make it possible.

~~~
scoot
Plusejet?
[https://en.wikipedia.org/wiki/Pulsejet](https://en.wikipedia.org/wiki/Pulsejet)

And if you haven't come across Colin Furze yet, you're in for a treat!
[https://www.youtube.com/watch?v=zsXWspo5hrc](https://www.youtube.com/watch?v=zsXWspo5hrc)

~~~
z2
Interestingly enough a video was just uploaded today on a printed Tesla
pulsejet engine that incorporates a Tesla valve.

[https://www.youtube.com/watch?v=28XbT11lL24](https://www.youtube.com/watch?v=28XbT11lL24)

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barbegal
This device will operate very differently depending on flow rate, therefore
the quote "the device acts as a slightly leaking valve" is probably a bit
misleading. The Reynolds number determines if the fluid operates in a
turbulent or laminar way. The slower the fluid, the lower the Reynolds number
and the more laminar it becomes and thus the less effective the valve is.

I can't really see many uses beyond microfluidic applications.

~~~
stazz1
Check out the original patent here
[https://patentimages.storage.googleapis.com/26/65/c7/c647a84...](https://patentimages.storage.googleapis.com/26/65/c7/c647a84af1f78f/US1329559.pdf)

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lvturner
What are the practical applications of this? (my imagination is having a
failure)

Are there any devices in the wild that use it currently?

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cardiffspaceman
The shape reminded me of schematic drawings of veins showing how they have
valves to constrain flow towards the heart. Arteries don't need that.

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ggm
I wanted a diagram or GIF. I get the idea, but boy, it would have helped if
wiki had some media.

~~~
Iv
[https://www.youtube.com/watch?reload=9&v=tcV1EYSUQME](https://www.youtube.com/watch?reload=9&v=tcV1EYSUQME)

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jcims
Beat me to it, i thought this was a cool demonstration. I wonder if blowing
some fine combustible material, like corn starch, would give embers that we
could see to help visualize the flows more precisely.

Also i wonder if these could be used as a suppressor.

~~~
Iv
I think this is a cool but really not proper way of showing airflows. Better
just add sparkling dust or use Schlieren imaging.

