Hybrid Continuum–Direct Simulation Monte Carlo and Particle-Laden Flow Modeling in the Head-Disk Interface Gap

Airflow modeling in the vicinity of the head-disk interface (HDI) gap in a modern hard disk drive (HDD) enclosure using the direct simulation Monte Carlo (DSMC) method is discussed. A hybrid continuum-DSMC model based on the Schwarz Alternating method is employed to couple the rarefied flow in the HDI region which is modeled by the DSMC method to the continuum flow outside the slider modeled by the Navier-Stokes equation. The hybrid coupling is done with the aid of overlap regions which are considered in two dimensions and the Chapman-Enskog molecular velocity distribution is used to impose boundary conditions from the continuum region to the DSMC region. Modeling of particle-laden flow in the HDI gap is also described in this work. A two-phase model has been incorporated in a parallel three dimensional DSMC method to enable computation of particle trajectories in the HDI gap. The two-phase model is based on computing forces acting on a particle under rarefied gas flow conditions.