Simulating particle collisions in homogeneous turbulence with kinematic simulation – A validation study

Particle collisions in homogeneous isotropic turbulence are simulated by means of kinematic simulation (KS) and compared with direct numerical simulation (DNS). KS is a computationally efficient surrogate for DNS of flow field dynamics [23]. To determine the energy spectrum in the KS, the Reynolds-number-dependent model spectrum of Pope was applied. For the comparison, particles having Stokes numbers ranging from 0.01 to 8 were considered and the DNS study of Sundaram and Collins [2] was used as a reference. Particle collision statistics like collision frequencies and particle concentration distributions resulting from KS and DNS were compared. Even though the KS collision frequencies were found to be in good agreement with the DNS reference for St > 2, deviations were observed in the particle mean relative velocity and radial distribution function of particles. Moreover, the extent by which particle collisions occur in KS-based flow fields was found to depend on the KS persistence parameter. This parameter controls the frequency of velocity fluctuations in a KS.