iridiu

Considering this article: http://www.popsci.com/article/technology/fuel-less-space-drive-may-actually-work-says-nasa and this two videos:

https://www.youtube.com/watch?v=i0kb8dYL0lQ

https://www.youtube.com/watch?v=bKDasXphJrE

In these rudimentary constructions I acquired a superior thrust force compared with space drive tested by NASA, using only electricity.

Agree, electric current is not a force, it's energy. What I wanted to say is that between circuit and exterior is an exchange of energy, even if the circuit is closed in an imaginary box, it is not an isolated system, there is an interaction.

Let's suppose that in the circuit is no pump and the fluid is moved by electromagnetic fields (MHD), in this case we have direct interaction between electric current (elctromagnetic fields) and fluid. It is known that electromagnetic fields (waves) can carry energy and momentum.

As I posted in my first response to you - if it is a circuit then you will get no net force. Think of it this way - put an imaginary box around the device and analyse the box and its contents as a system; what external forces act on the system? None. No external forces mean no change of momentum for the centre of mass of the system

Circuit is a system, even if it's not closed in a box and there is an external force: electricity.

I think it can be superior to Ion Thruster with the same applications, by several aspects:

1. It can use only electricity (no fuel needed)

2. Does not expel reaction mass

3. It is not in contact with the environment

4. Reduced size and weight

"Therefore ion thrusters create very small levels of thrust(for example thrust engine Deep Space 1 approximately equals the weight of one sheet of paper^[1]) compared to conventional chemical rockets but achieve very high specific impulse, or propellant mass efficiencies, by accelerating their exhausts to very high speed." - Wikipedia - http://en.wikipedia.org/wiki/Ion_thruster

This system can be regarded as a possible thruster?
I know that currently, the idea is still in the incomplete stage, but look at it as an unconventional possibility.

Thank you very much for your answers and I hope you will allow me to present another example related to trajectory translation.

In this example, reaction is represented by the force exerted by the pipe walls on the forward path of the fluid, and from there result a change of trajectory equivalent with the distance "d" between the point of entry of the fluid "1" and the output point of the fluid "2". From this change of trajectory of the fluid results a linear force (reaction force) which occurs simultaneously and opposite in direction, according to Newton's third law of motion, in the following conditions:

1. If the fluid goes out at the same velocity as it comes in, there should be no net force on the pipe.

2. Preserving the velocity vector, doesn't change the momentum of the fluid.

I did a practical experiment (rudimentary), I pushed water through a elastic spiral pipe with a diaphragm pump:

And the result:

https://www.youtube.com/watch?v=i0kb8dYL0lQ

The fluid comes back where it came from, but there is momentum exchange.
I think, with a system which generates custom compressibility and pressure wave propagation, there we can have short term instantaneous net forces on the pipe, but I don't have enough knowledge to make it possible.

Do you understand the principles of momentum balance in fluid dynamics?

Most of my knowledge in fluid dynamics I have accumulated using google, now using this forum I hope to understand better from users who have advanced knowledge.

I need your help to solve the following problem:
Let's suppose we have a pipeline as in the drawing attached and inside it circulates a fluid whose trajectory is changed. From this change of trajectory of the fluid, results a reaction force which is equal with the force exerted by the pipe walls on the forward path of the fluid, in opposite direction, while the velocity vector is changing.