Particle segregation in turbulent Couette–Poiseuille flow with vanishing wall shear

摘要

Highlights?Wall-normal segregation of inertial spherical particles in a specific asymmetric turbulent Couette-Poiseuille flow with vanishing wall shear was demonstrated and explained.?The particle wall-normal segregation may appear near shear-free walls, depending on particle inertia. The near-wall coherent turbulent structures are strong and local in the flow, and are not a prerequisite for the particles to segregate near the wall region. They do, however, perform an inertial selection and determine the actual segregation ability of the particles.?The LSSs are weak but global in the flow, which play an important role in the wall-normal particle segregation.AbstractInertial particles dispersed in wall-bounded flows in pipes and channels are known to accumulate close to the walls. The segregation ability depends greatly on the inertia-selection effects of the near-wall quasi-coherent turbulent structures, which are formed near both walls where shear stresses are high.