Exploring Ferrofluid Behavior with Magnets

[THORPE]

I understand the basics of Ferrofluid and how it works and reacts to a point. I have never had the chance to actually play with it to see the effects when magnets are applied.

I understand that it (when used as a dampener) gets stiffer when the magnetic field is present.

My question is what happens to it if say... you put it in a cylinder and had opposing magnets on each end inside of the cylinder like pistons. does it progressivley thicken as the magnets are brought closer to each other?

I've seen how the active suspension dampening works in some automobiles but curious as to behavior with permanent magnets.

 

[THORPE]

Surely somebody knows?

Did I ask it in a confusing way?

 

[Andy Resnick]

My (limited) understanding is that the viscosity of a ferrofluid increases with the applied magnetic field. Moving permanent magnets closer to the ferrofluid increases the magnetic flux density, so the viscosity should increase.

Or are you asking about something else?

 

[THORPE]

That's the way I understand it too.

What I don't know it what happens when the fluid is between to opposing magnets ( repelling) .
Does it make a difference?

 

[THORPE]

I need to clarify...

What happens with the fluid when the opposing magnets are brought closer to each other?

Is there any difference in the behavior of the fluid compared to being in a magnetic field in the same direction (attracting) ? Or does it act like a single magnet would?

 

[Phrak]

Ferrofluid develops spikes in regions of strongest magnetic field. In regions where there is little field strength, such as opposing magnets, the spikes will not form.

 

[THORPE]

Ferrofluid develops spikes in regions of strongest magnetic field. In regions where there is little field strength, such as opposing magnets, the spikes will not form.

Thanks! That's what I was looking for.

So I guess it would increase when 2 attracting magnets are brought closer to each other.

Either way I guess it cancels out my idea LOL.

Thanks again for the info!

 

[THORPE]

Another property of the ferofluid you might want to consider is that it losses permeativity as it heats up. And it heats up if it moves a lot. So if you are intending to use it in a transmition, than most likely it would loose its efficiency after few minutes of use.

Hmmm. What's the difference in the Mr fluid used in Active Suspension?

And also I thought it acted in a cooling agent in speakers.

My idea is for an R/C car application: Suspension configuration.

 

[Robin07]

Ferror fluid has convective properties, essentially circulating hot fliud areas with cooler fluid