Investigation of Mach number and relative position effects on aerodynamic interference between two particles by direct numerical simulation

In the present study, the effects of Mach number and relative position on aerodynamic interference between two particles were investigated by direct numerical simulations of compressible Navier-Stokes equations. The particle Reynolds number was set to be 150, and the particle Mach number was set to be between 0.3 and 1.2. The apparent attractive and repulsive directions acting between the two particles were calculated from the aerodynamic coefficients of those particles. The apparent force in the repulsive direction is generated only in the side-by-side arrangement, and the force in the attractive direction is generated in the in-line and diagonal arrangements. In addition, attractive and repulsive forces are larger at high Mach numbers than that at low Mach numbers. This result suggests that the influence of interparticle interaction on the particle distribution in compressible particle-laden flows might be stronger than that in incompressible cases. However, the aerodynamic interference is significantly reduced at the Mach number of 1.2 with a certain condition. This is because the influence of particles on the flow field is spatially limited due to the formation of the bow shock. The critical distance is related to the angle of the detached shock wave.