Effect of particle size on turbulence modulation in Particle Resolved DNS of a turbulent neutrally buoyant particle-laden channel*

The modification of turbulent structures by finite size particles is of interest to pipeline design for oil and slurry transport. The role of particle size in turbulence attenuation or enhancement is poorly understood. We investigate the interaction of finite size particles with turbulent flow structures in Particle-Resolved Direct Numerical Simulations of turbulent channel flow at friction Reynolds number 180, laden with neutrally buoyant, spherical finite size particles, dispersed at volume fraction 10%. Particle diameter is varied from 20.2 to 40.4 wall units, in order to elucidate the role of particle size in turbulence modulation. We use the recently developed volume-filtering immersed boundary method to track and represent between 4650 and 600 resolved particles, which accounts for stresses at the fluid solid interface. Additionally, we collect turbulence statistics from a particle free channel for comparison with the particle laden channels.