The variation in wall shear stress induced by a linear train of soft particles in channel flow

Abstract

We investigate the wall shear stress variation induced by soft particles modeled as capsules migrating in a channel. Interestingly, the wall shear stress exhibits a roughly linear increase in both its global maximum value and variation magnitude with an increase in the normalized overall lateral position of the capsules when they stabilize as a linear train. Furthermore, when a single capsule stabilizes in the channel centerline, the streamlines show an M-like shape in the upper part and a W-like shape in the lower part of the channel. Meanwhile, we use the vertical velocity to explain the typical peak-valley-peak structure in the wall shear stress profile. For multiple capsules, the contours of the vertical velocity can also be employed to determine the locations where the peaks or valleys in the wall shear stress occur. These findings enhance our comprehension of the variation in wall shear stress caused by soft particles.