Why does dust stick to fans

Yes, as it turns out! First step, you need to clean off the offending ceiling blade fans before any solution might work. I recommend getting a pillowcase or another bag to collect the bulk dust that might fall down. My personal favorite way of quickly moving dust is using a damp not wet paper towel or cloth. If you get the towel too wet, then it will form a slurry that is more difficult to clean. Second, there is one piece of equipment that you probably have in your house that specializes in removing static cling from surfaces.

Dryer sheets. If you wipe down the surface of the fan blades with dryer sheets, it should help dislodge any remaining dust, and the fabric softener can help to prevent further buildup, at least temporarily. Then you might try a different product that works against static electricity, such as hairspray or static guard. One alternative to performing a dusting ritual is to try an anti-dust ceiling fan. These work by repelling water away from the fan blade, which encourages it to bead up like on a piece of wax paper.

Over time, the water will capture dust particles, and eventually the droplet is blown away, supposedly with the dust in tow. Simply put, dust particles collect on your ceiling fan blades due to one of the following reasons:. Static electricity happens when the fan blades travel through the air quickly and brush the air molecules to move them out of the way. These molecules will build up an electrical charge on the leading edge of your fan blade, which is why dust particles will collect and stick more to one side than the other.

As time progresses, existing dust particles will continue to attract more particles, increasing the amount that resides on top of the blades. In other words, your fan blades are moving charged electrons which attracts dust that is floating in the surrounding air. Airflow and fluid dynamics are other reasons for dust build up on your ceiling fan blades, especially if they are metal blades. While it may sound complicated, the explanation is quite simple.

While the blades move through the air continuously, the air that resides directly above the fan blades does not move. In other words, all the air surrounding the fan blades will move, except the air between the fan blades and the ceiling. I Mark took photos my the fan my room to support Damien's hypothesis.

The first photo is of the leading edge of the fan blade, which impacts a lot of air, and the second photo is of the trailing edge of the same fan blade. I've never cleaned this fan. The leading edge is covered in a thick, mm layer of dust, while the trailing edge is almost clean. Wind doesn't actually touch the surface. You can see the same effect on a car: even if you move at speeds beyond 70mph, the dust doesn't get blown away. If you look closely, there is a boundary layer between the matter of the fan and the air around the fan.

When you get closer to the fan blades, the air starts to move with the fan the blade pulls it along , so air very close to the blade doesn't move much relative to the blade itself. Obviously, this is true when you add matter to the blade like dust. In this case, the friction of the air is less than the adhesion of the dust to the blade, so the dust sticks to the surface. On my fans, I find a lot of dust and short strands on the edge that cuts the air.

Here, the air flow presses the strands to the blade parts of it on either side of the edge. This way, the fan actively collects dust. Again, the force of the air pressing the strands against the blade plus the friction between dust and blade is much stronger than the centrifugal force which might pull them sideways.

Since the strands cling to the surface, the blade isn't strong enough to cut them, so they stay where they are. A simple countermeasure is a coarse net on the side where the fan sucks the air in.

Most dust strands will get caught in the net and you can easily wash them away every few weeks or collect them with a vacuum cleaner. The short answer is that there's no wind near the blade. This is called no-slip condition in hydrodynamics of viscous fluids.

There's minor van der waals sticking which contributes to this otherwise purely hydrodynamic phenomenon. First taking only speed of the fan into the account. If the fan rotates slowly then the situation is obviously not very much different from if it weren't rotating at all. The centrifugal force on the dust particles is not big enough to throw them away off the fan. Second, there's static electricity that has to be taken into the account. It's perfectly possible that some residual charge is generated on the fan this depends very much on what is the fan made off and as the dust particles are often charged the ones with correct polarity will get attracted to the fan.

In this case they would stick even if fan were rotating very fast. Now, you can test whether the second option is realized in your case by touching the fan to discharge it and it should "kick" you a little. Or if you don't like that you can bring some charged object close to the fan and see whether it is affected. Dust sticks almost anywhere. Yes almost, because yet we don't have no super perfect nano-surfaces. The point is that every macroscopic surface is raspy and not perfectly smooth.

Therefore very small dust can easily stick. This very small dust makes the surface even more raspy, making it easy for the heavier dust to arrive. And of course it is the electro-magnetic force that lets the dust stick. Make yourself clear how very, very small pieces of dust look like and you understand how it can easily stick on a non-smooth surface by means of the Coulomb-Force.

In the end: Most things you see are electrically charged, at least if you "zoom in" a lot. Looking from far away the charges are effectively neutralized. Of course a super perfect nano surface even looks very good is you "zoom in". Dust sticking to things is a complex process but can be broken down into several stages and analyzed. First though lets define our dust.

Each particle is assigned an aerodynamic diameter that is the diameter of one of these hypothetical spheres that would fall at the same rate as the actual particle gravity and air resistance balance at the same settling velocity for the sphere and real particle.

Whenever an unqualified particle size is mentioned, this post is referring to this aerodynamic diameter. This diameter range will determine the magnitudes of the forces that act on the dust. In order for dust to accumulate, it has to come from somewhere. I won't go into how dust gets into the air, but lets presume that well circulated air has a constant concentration of dust that is renewed through generation, mixing, and diffusion.

Normally, dust that accumulates on surfaces approaches those surfaces by settling; gravity pulls the particles downward so that their average velocity is downward this is why horizontal surfaces accumulate dust while vertical ones generally accumulate much less.

For a ceiling fan, the rate at which dust approaches the surfaces is not dominated by gravity but rather by the speed that the blade moves through the air. If dust arrival were the only thing important for dust accumulation then fans would accumulate dust about 50 times faster than a horizontal surface. For particles to hit the blade they will have to move towards the blade, but the air must flow around the blade.

This necessitates that the particles move relative to the air. In the case of dust settling this is accomplished through gravity, and diffusion.

The dust that accumulates on walls is due to diffusion, while gravity pulls the dust onto horizontal surfaces. Initially I would say it's static RDL Posts: 2, And you really don't want to know what that dust is actually made of Beau Schwabe wrote:.

ElectricAye Posts: 4, I think part of the problem stems from the boundary layer that exists anytime you have flow over a surface. Microscopically speaking, the velocity at the surface can be almost zero, so there probably isn't as much force acting to wipe off the dust as you might expect.

With plastic, you have not only the electrostatic problem, but also the fact plastic scratches easily especially microscopically so you've got lots of little hand-holds for the dust to grab hold of. Not to mention that spores of fungi and bacteria have electrostatic properties that help them disperse.

The cosmos is a clingy kinda place. I was pondering. I don't think it would It looks there are a bunch of factors. I thinking of trying an experiment this week with some mm ATX fans.

I don't quite understand the static relationship between metal and plastic. I know metal can build up a charge but like Phil said if it's grounded how would static be a factor there. The boundary layer is talked about a lot, how there is no velocity at the surface, that might be why I'm confused I've never heard of that, good stuff. I can use a Propeller to control the power of and monitor the RPM of the fans.

I guess the fans all need to have the same airflow, speed, environment and surface area which can't be too hard to pull off. I'm thinking run it for a month and check the blades in 48 hour intervals with a basic microscope and also digital camera and make a time lapse or cool comparison at least.

Phil Pilgrim PhiPi wrote: ». Bring a charged object near an electroscope and the leaves on the electroscope move apart, yet no charge has actually transferred between the charged object and the electroscope, yet the leaves still repel.

This is because induced charge at one end of the electroscope creates an imbalance