since it seems like participating in bounty questions is something like our group sport, I could not resist to also think about the question.

I think the answers given according to the vanishing velocity on the propeller are unlikely to explain the phenomenon. Dust particles, even though they are very thin, have a three dimensional shape. So even if there is no velocity at zero distance (which is the mentioned boundary condition), there will be a relative movement along the dust particle (Remember that turbulence takes place on every scale for the Navier-Stokes equations) which to my opinion acts as a pulling force on the particle.

To my mind, the problem relates to an electrostatic one. The propeller is very likely to have some charge due to his movement through air and the ongoing friction. The (might even be very small) charge induces a dipole moment on the dust particles nearby which I guess might be treated as dielectric balls.

This dipole moment will then attract the dust particles which as a result touch the surface. If now everything would be metal, there would be immediate (full) charge balance and the attractive force would vanish. But under the assumption of a dielectric medium, some dipole moment stays, so does the attractive force and the dust on the propeller.

Greetings

Edit: I just saw that the electrostatic argument already came up. Nevertheless, I hope my explanations are still usefull.

I think the answers given according to the vanishing velocity on the propeller are unlikely to explain the phenomenon. Dust particles, even though they are very thin, have a three dimensional shape. So even if there is no velocity at zero distance (which is the mentioned boundary condition), there will be a relative movement along the dust particle (Remember that turbulence takes place on every scale for the Navier-Stokes equations) which to my opinion acts as a pulling force on the particle.

To my mind, the problem relates to an electrostatic one. The propeller is very likely to have some charge due to his movement through air and the ongoing friction. The (might even be very small) charge induces a dipole moment on the dust particles nearby which I guess might be treated as dielectric balls.

This dipole moment will then attract the dust particles which as a result touch the surface. If now everything would be metal, there would be immediate (full) charge balance and the attractive force would vanish. But under the assumption of a dielectric medium, some dipole moment stays, so does the attractive force and the dust on the propeller.

since it seems like participating in bounty questions is something like our group sport, I could not resist to also think about the question.

I think the answers given according to the vanishing velocity on the propeller are unlikely to explain the phenomenon. Dust particles, even though they are very thin, have a three dimensional shape. So even if there is no velocity at zero distance (which is the mentioned boundary condition), there will be a relative movement along the dust particle (Remember that turbulence takes place on every scale for the Navier-Stokes equations) which to my opinion acts as a pulling force on the particle.

To my mind, the problem relates to an electrostatic one. The propeller is very likely to have some charge due to his movement through air and the ongoing friction. The (might even be very small) charge induces a dipole moment on the dust particles nearby which I guess might be treated as dielectric balls.

This dipole moment will then attract the dust particles which as a result touch the surface. If now everything would be metal, there would be immediate (full) charge balance and the attractive force would vanish. But under the assumption of a dielectric medium, some dipole moment stays, so does the attractive force and the dust on the propeller.

Greetings

since it seems like participating in bounty questions is something like our group sport, I could not resist to also think about the question.

I think the answers given according to the vanishing velocity on the propeller are unlikely to explain the phenomenon. Dust particles, even though they are very thin, have a three dimensional shape. So even if there is no velocity at zero distance (which is the mentioned boundary condition), there will be a relative movement along the dust particle (Remember that turbulence takes place on every scale for the Navier-Stokes equations) which to my opinion acts as a pulling force on the particle.

To my mind, the problem relates to an electrostatic one. The propeller is very likely to have some charge due to his movement through air and the ongoing friction. The (might even be very small) charge induces a dipole moment on the dust particles nearby which I guess might be treated as dielectric balls.

This dipole moment will then attract the dust particles which as a result touch the surface. If now everything would be metal, there would be immediate (full) charge balance and the attractive force would vanish. But under the assumption of a dielectric medium, some dipole moment stays, so does the attractive force and the dust on the propeller.

Greetings

Edit: I just saw that the electrostatic argument already came up. Nevertheless, I hope my explanations are still usefull.