Evaluation of drag and lift forces on nonspherical particles in a gas

The nonspherical particles suspended in a gas flow will experience drag and lift forces, which dominate the transport properties and dynamics behaviors of nonspherical particles. In this paper, forces on nonspherical particles suspended in a gas are evaluated using the direct simulation Monte Carlo method, wherein the Knudsen number is in the range of 0.01 ≤ Kn ≤ 50. The aspect ratios of nonspherical particles and the incident angles (the angle between the polar axis of a nonspherical particle and the direction of gas flow) are key factors that lead to the transport dynamics of nonspherical particles different from spherical particles. It is found that the theoretical formulas for the orientation dependence of the drag and lift forces in the continuum regime can be extended to the transition and free molecular regimes. Considering the random rotating of particles in a gas flow, the orientation-averaged drag force can be employed to describe the particle transports, which is found to be equal to the drag force on spherical particles with the equivalent spherical surface-area approximation.