A novel surface-slip correction for microparticles motion

As the fine particles expose to the rarefied regimes, the solid-surface effects become prominent and change the interfacial interactions between the gas and particle. The particle drag force, which is mainly concerned in aerosol researches, is affected through the changes observed in the way that fluid entities reflect from the particle surface. A 3D simulation study for an incompressible rarefied slip flow past a spherical aerosol particle was performed. The full Navier–Stokes equations were solved and the velocity jump at the gas–particle interface was treated numerically by imposition of the slip boundary condition. Analytical solution to the Stokesian slip flow past a spherical particle was used as a benchmark for code verification, and reasonable agreement was achieved. The simulation results showed that in addition to the Knudsen number, the Reynolds number affects the slip correction factor. Thus, the Cunningham-based slip corrections must be augmented by the inclusion of the effect of Reynolds number for application to Lagrangian tracking of fine particles. A novel expression for the surface-slip correction factor as a function of both Knudsen number (0.01 < Kn < 0.1) and Reynolds number (0 < Re < 1) was developed.