Influence of uniform momentum zone on inertial particle distribution in wall turbulence

Direct numerical simulation was performed to particle-laden turbulent channel flow at the friction Reynolds number of 1000 and particle Stokes number of 1.0. Superposed Gaussian functions were adopted to extract the modal velocity of uniform momentum zone (UMZ). The particle distributions in each UMZ were studied. In the quiescent core region with large fluid momentum, the particle concentration is higher and the concentration fluctuation is lower than those in the non-core region. Distinct abrupt change of velocity and particle concentration exists at the UMZ interface. The presence of spanwise vortical structures leads to the local minimum value of particle concentration. Beneath the UMZ interface at high wall-normal position, there exists large-scale regions with low concentration magnitude and high concentration fluctuation. The contour of the concentration is in consistent with the shape of the turbulent/non-turbulent interface.