Particle Image Velocimetry measurements in a turbulent channel flow laden with elongated particles

Particle Image Velocimetry is employed to investigate the turbulence modulation induced by dispersed elongated, rod-like particles in a turbulent channel flow. Particles with two different aspect ratios AR=40,80 are tested, at a volume fraction of 10-5. Carrier flow velocimetry data and distribution and orientation data of dispersed particles are obtained by an ad-hoc single-camera phase-discrimination technique. Carrier flow data shows that in the near-wall region turbulence modulation by particle occurrs as well as a decrease of average streamwise velocity. Analysis of conditional probability density function of particles location reveals that particles locations statistically match flow regions with instantaneous low vorticity and high streamwise velocity, in particular in the near-wall region.