2016/12/31 by Iman Lashgari, Francesco Picano, Pedro Costa +2 · 17 citations
Engineering · Environmental Science · Physics and Astronomy · #Drag #Granular flow and fluidized beds #Hydrology and Sediment Transport Processes #Materials science #Mechanics #Particle (ecology) #Particle Dynamics in Fluid Flows #Particle size #Particle-laden flows #Physics #Reynolds number #Turbulence #physics.flu-dyn
paper · pdf · doi:10.1017/jfm.2017.148
published in Journal of Fluid Mechanics 818, 623-645 (Cambridge University Press) · 22 pages, 12 figures
arxiv created 2017/02/28 · openalex publication_date 2017/04/05 · arxiv updated 2021/02/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study turbulent channel flow of a binary mixture of finite-sized neutrally buoyant rigid particles by means of interface-resolved direct numerical simulations. We fix the bulk Reynolds number and total solid volume fraction, Reb=5600 and \unicode[STIX]x1D6F7=20 % , and vary the relative fraction of small and large particles. The binary mixture consists of particles of two different sizes, 2h/dl=20 and 2h/ds=30 where h is the half-channel height and dl and ds the diameters of the large and small particles. While the particulate flow statistics exhibit a significant alteration of the mean velocity profile and turbulent fluctuations with respect to the unladen flow, the differences between the mono-disperse and bi-disperse cases are small. However, we observe a clear segregation of small particles at the wall in binary mixtures, which affects the dynamics of the near-wall region and thus the overall drag. This results in a higher drag in suspensions with a larger number of large particles. As regards bi-disperse effects on the particle dynamics, a non-monotonic variation of the particle dispersion in the spanwise (homogeneous) direction is observed when increasing the percentage of small/large particles. Finally, we note that particles of the same size tend to cluster more at contact whereas the dynamics of the large particles gives the highest collision kernels due to a higher approaching speed.