Interface-resolved numerical simulations of particle-laden turbulent channel flows with spanwise rotation

Abstract

Interface-resolved simulations of particle-laden turbulent channel flows with spanwise rotation at a Reynolds number of 180 and different rotation numbers ranging from 0.1 to 1.0 are performed with a fictitious domain method. The difficulty of the centrifugal force on the particles not satisfying the periodic boundary condition is circumvented by the feature of the fictitious domain formulation for the neutrally buoyant case, where the centrifugal force in the particle motion equation vanishes, and by only considering a low rotation number of 0.1 and setting the rotation center to be far away from the channel for the non-unity density ratio case. Our results show that the heavy particles (i.e., the particle density being larger than the fluid density) migrate towards the pressure wall, whereas the light particles migrate towards the suction wall. For the density ratio being unity, the particle concentration is higher near the pressure wall than near the suction wall, and we attribute the reason to the effects of the mean secondary flow structure (i.e., the Taylor–Görtler vortices), since similar particle concentration distribution and secondary flow structure are observed in a rotating laminar channel flow. The mean velocities of heavy particles are smaller in the pressure-side half channel except the near-wall region, and larger in the suction-side half channel, compared to the fluid mean velocity; the opposite occurs for the light particle case. The addition of the finite-size particles increases the flow drag. The flow drag is not sensitive to the density ratio for the light particles and increases with increasing density ratio for the heavy particles. The effects of the particles on the fluid root-mean-square velocities of the rotating turbulent channel flow are generally similar to the non-rotating channel case, but become more complicated because of the asymmetric turbulence intensity and particle concentration distribution near two walls caused by the channel rotation.