Effect of diffusion of magnetic particles on the parameters of the magnetic fluid seal: A numerical simulation

Abstract

In the paper, a motion of magnetic nanoparticles in a high gradient magnetic field and its correlation with the characteristics of the magnetic fluid seal are numerically studied. The neutral curve defining a range of parameters, where the liquid keeps fluidity, is found. It is shown that the concentration of particles during the initial time period grows linearly and then the exponent decreases to 0.5 with time. It is found that at a high enough value of magnetic field the area of close-packed particles is formed under the pole tip. Numerical simulation has shown that with some values of the parameters it is possible to decrease the magnetic particles' concentration essentially so that the basic fluid leaks out from the seal under gravity, i.e. the magnetic fluid seal fails. It has appeared that the characteristic time of the described processes depends on the properties of magnetic fluid and on the magnetic field value and has an order from several hours to several years.