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How can I make current flow straightly by using ground and floating potenial node?

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Hi everyone I need you guys help very very much........!!!

These day I am doing simulation about current flow at AC/DC module, stationary. Plus, my goal is to observe ideal current density flow.

In my simulation, I set cylindal shape electrode (which is crossed out from electrolyte material which has same conductivity and permittivity everywhere). Cuz I don't want all of my face of electrode let current comes out, I select only bottom area to spew current (1uA) by using floating potential. Also, another faces can't flow current cus I put them into insulation node. And last but not least, I set ground below them. ( It is because I thought if I put ground below, there will be more ideal current flow.)

However, my simulation result was very different from what I expect. I thought when I set arrow volume after computing, all of arrows direction would be go down toward ground, but it wasn't. Many of them are going up!! I think I did something wrong,,but I don't know what is it....

I attatched my simulation result below. Can anybody tell me what's wrong?? If you want more information, you can mail me also..! here is my e-mail address. bg0529@naver.com

Thank you in advance :)



1 Reply Last Post 18 oct. 2021, 15:39 UTC−4
Jeff Hiller COMSOL Employee

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Posted: 3 years ago 18 oct. 2021, 15:39 UTC−4
Updated: 3 years ago 20 oct. 2021, 09:17 UTC−4

Hello Yunseo,

It's always challenging to say anything useful while working from a screenshot, but I'll give it a shot.

I am assuming that all side boundaries and the top boundary are insulated.

Even under those circumstances, I would not expect all arrows to be pointing straight down. A streamline needs to connect every point on the grounded bottom to a point on the electrode surface that has a set current, and the entire volume will be filled with streamlines; that's not possible if the current went straight down from the electrode. With that said, I would expect that the magnitude of the current density would be greatest along the path of least resistance, ie in the region right between the bottom of the electrode and the ground condition, and that is not the case in your screenshot. So something does seem off with your model set-up. Please post your .mph file and users of the Discussion Forum, myself included, may be able to give you more detailed feedback.

Best,

Jeff

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Jeff Hiller
Hello Yunseo, It's always challenging to say anything useful while working from a screenshot, but I'll give it a shot. I am assuming that all side boundaries and the top boundary are insulated. Even under those circumstances, I would not expect all arrows to be pointing straight down. A streamline needs to connect every point on the grounded bottom to a point on the electrode surface that has a set current, and the entire volume will be filled with streamlines; that's not possible if the current went straight down from the electrode. With that said, I would expect that the magnitude of the current density would be greatest along the path of least resistance, ie in the region right between the bottom of the electrode and the ground condition, and that is not the case in your screenshot. So something does seem off with your model set-up. Please post your .mph file and users of the Discussion Forum, myself included, may be able to give you more detailed feedback. Best, Jeff

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