Experimental study on the local turbulence modulation in a horizontal particle laden flow with rigid fence

The turbulence modulation by the existence of disperse phases, e.g. solid particles or liquid droplets, has attracted wide attentions in recent years. In this investigation, particles of different properties were fed with tracers into the turbulent atmospheric boundary layer disturbed by a rigid fence, and the velocities of both phases were obtained by PIV/PTV methods respectively. From both ensemble average and instantaneous analysis, the presence of particles was found to attenuate the local turbulence around the fence and in the downstream. In this case, the induced sand dune erosion by the turbulence when installing the rigid fence is also expected to decrease. The influences of the particles follow the order: GH>GL>No.9. The Stokes number under the given conditions showed that all the particles under discussion should cause augmented dissipation of turbulence. Moreover, through analyzing the relative velocities between the two phases, the cross-trajectory effect was found to be another possible mechanism accounting for the observed turbulence modulation by the particles.