Simulation of Air Flow and Particle Trajectories in the Head–Disk Interface

A numerical method is presented to study the air-flow pattern and particle trajectory in the head-disk interface (HDI) in this paper. It first solves the generalized steady-state Reynolds equation with slip boundary conditions to get the slider attitude. Then, it solves the reduced Navier-Stokes equation to get the air flow velocity distribution in the HDI. The motion equations of particles are solved to obtain the particle trajectory in the HDI by using the fourth-order Runge-Kutta method. Air flow characteristics and particle behaviors are investigated to illustrate the relationship between the air flow and particle trajectory. The effect of the particle release height is also studied. The simulation results show that particle trajectories basically overlap air flow streamlines in the horizontal plane. The particle moves a longer horizontal distance at a lower particle release height. The difference between the horizontal velocity of the particle and the air flow indicates that the Saffman force points to the disk in the transition region close to the leading edges of leading pads. Moreover, the peak values of the air flow vertical velocity in the previously mention location increase with the reduction of the particle release height. And the air flow vertical velocity along the particle trajectory is almost two times larger than that of the particle at the leading edges of leading pads. The results also show that the drag force of the air flow mainly drives particles up toward the air bearing surface at the leading edges of leading pads, but not the Saffman force.