# Ion flow through a charged tube

Summary:
What will happen when ions flow through a metal tube that has the same charge as the ions? As both has same charges, do the boundary layer will still form?
Suppose we have a charged metal tube through which charged ions of compressible fluid is passing. I want to know whether the boundary layer will still form that will resist the flow or the flow will be smoother. We all know how strong electromagnetic force is and this will push the ions away from each other. Does that means drag will be much less?

As there is no response from anybody, it seems that this is a totally uncharted territory.

We all know how strong electromagnetic force is
Electromagnetic force is really strong, it's just usually the charges voltages involved are limited. If it's really about some unspecified 'compressible fluid' then within the usual limits you would need to struggle quite a bit to measure any effect.

Re-specifying the problem (with more details and some drawings included) would help to draw in more interest.

russ_watters
Not very complicated to imagine. Just think of a tube and a gaseous flow inside. The only speciality is that both the tube and the flow is charged.

russ_watters
Mentor
As there is no response from anybody, it seems that this is a totally uncharted territory.
It's just really vague/handwavey and maybe a little nonsensical. But the generic answer is no, you can't reduce drag by applying an electric charge to a duct.

In that case, I am curious how the boundary layer will behave.

russ_watters
Mentor
In that case, I am curious how the boundary layer will behave.
The answer to that is going to be very complicated and heavily dependent on the specifics of the scenario being analyzed.

That's why looking for references here. If anybody knows any reference, kindly post here.

The scenario is pretty simple. There is a metallic tube that is charged to certain voltage and through it, there is a flow of ions (same charge as the tube) through it. My question is how the boundary layer will behave in such a scenario.
Electrokinesis is generation of flow by just using electric charge instead of mechanical moving parts. Point is whether the viscous drag will be same in case of electrokinesis or different.

russ_watters
Mentor
The scenario is pretty simple. There is a metallic tube that is charged to certain voltage and through it, there is a flow of ions (same charge as the tube) through it.
That isn't a fully defined scenario - it's basically nothing.

And I'm sorry but given the difficulty you had in the Venturi Effect thread, I'm not confident that you are capable of properly defining even a simple scenario (which this is not). It seems like you think you are saying something useful, when in reality you are not. You are barely saying anything at all.

Nor do I think it is likely that you understand the question you are asking. This is probably why you aren't getting more/more helpful responses; people don't see any content that can be responded to.

Keith_McClary
Gold Member
If a metal tube is charged, won't the charge all be on the outside, with no effect inside?

If a metal tube is charged, won't the charge all be on the outside, with no effect inside?
How can you say that?

Keith_McClary
Gold Member
How can you say that?
The electric field is pointing radially outwards, assuming a long tube so we can ignore end effects.

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russ_watters
Tom.G
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That doesn't mean that all charges are concentrated at the outer side of the tube.
Sure: with all charges it would mean the tube disintegrated.

But all excess charge will be there, with no electric field within (not from local charges on the tube, at least).

But all excess charge will be there, with no electric field within (not from local charges on the tube, at least).
My actual question is how viscous drag will behave inside the tube in such a condition. As both the tube and the flow inside is charged, do the ions will accumulate and stuck to the inner walls of the tube just like a normal electrically neutral flow or not.
And as per this page, in case of excess charge accumulated on a conducting surface, all charges will be distributed all over the surface in such a way that the repulsive forces will be minimum. If all charges accumulate just on the outer surface, that wouldn't be the case. So, all charges will be distributed evenly on both the inner and outer surface.

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Keith_McClary
Keith_McClary
Gold Member
Are you saying that the liquid has a net ("excess") charge per unit volume?

Keith_McClary
Gold Member
charged ions of compressible fluid
Are you saying there is a net ("excess") charge per volume?

Of course. Both the tube and the flow is charged i.e. have excess charges (same charge).