Effects of the collision model in interface-resolved simulations of particle-laden turbulent channel flows

The effects of the particle collision model in a direct-forcing fictitious domain method on the fluid and particle statistics of a fully developed turbulent channel flow laden with finite-size neutrally buoyant particles are numerically investigated. The particle collisions are described by a combination of the discrete element method and the lubrication force correction model. We first validate our code via several benchmark tests, including the normal particle–wall collisions at different impact Stokes numbers and the oblique collisions with varied incidence angles. Subsequently, the effects of the lubrication correction and the particle stiffness on the fluid and particle statistics of the particle-laden turbulent flows are examined. The results show that the lubrication force correction has an important effect on the particle pair statistics at the near-contact regime. Both the lubrication force between the particles and the decrease in the particle stiffness result in the decrease in the flow friction mainly due to the increase in the fluid Reynolds stress. The flow friction is always larger for smaller particles at the same particle volume fraction irrespective of the lubrication correction. The particle–particle lubrication force decreases the near-wall particle concentration, whereas the particle–wall lubrication force has the opposite effect.