Fluidics and the Coanda Effect

Fluidics is the branch of engineering that applies hydordynamic principles in flow circuits for purposes such as switching, pressure and flow sensing, and amplification.

Principle of fluidic circuitry is the phenomenon of wall attachment, known as the Coanda Effect.



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Based on the Bernoulli effect (A) coupled with curved wall on one side of jet (B).

Can actually deflect fluidic stream through a 180o turn by carefully extending the wall contour

Subatmospheric pressure along wall directs flow until interrupted by counterforce (pulse of gas).

Gas flow pathway can be changed by side jets in devices called gates; pulses of air from the side jet cause an increase in pressure at the wall, breaks the attachment and allows the gas stream to attach to the other wall, which will stay adhered to that wall until a pulse of air from below causes it to switch back.


Advantages: Fewer valves and moving parts that can break

Disadvantage: Consume more gas


Fluidics – no moving parts required for switching, pressure and flow sensing.