Instability of dilute suspensions over and through riblets*

Understanding the flow behavior of suspensions has been of great importance due to the potential applications in the environmental, industrial, and pharmaceutical fields. This study is focused on the motion of a dilute, non-Brownian, neutrally-buoyant suspension of rigid spherical particles passing over and through a periodic two-dimensional riblet geometries transverse to the mean flow. We performed both particle image velocimetry and particle tracking velocimetry (PIV/PTV) techniques to examine the velocity, vorticity, and particle concentrations along the streamwise and spanwise directions and pressure drop measurements. We also analyzed in detail the flow and particle dynamics. The results clearly demonstrate that the flow instability in a channel with riblets occurs at much lower flow rates compared to the Newtonian solvent.