Experimental study of coherent structures in a solid-liquid turbulent boundary layer

Solid-liquid turbulent flows are common in industrial and engineering processes.Study of the interactions between particles as well as turbulence and turbulence modulation is extremely significant, which can play an guidance role in practical engineering application for heat and/or mass transfer in chemical processes.Coherent structure in the turbulent boundary layer of particle-laden flows is experimentally investigated using Particle Image Velocimetry (PIV). Study of the change of the mean velocity profile and the turbulent intensity in the horizontal turbulent boundary layer of water and with polythene is conducted, which is used as the dispersed phase.Based on the concept of multi-scale spatial locally averaged structure function, conditional sampling and phase average methods are employed to extract and analyze the spatial topologies of the streamwise and normal fluctuating velocities, spanwise vorticity, Reynolds shear stress of the ejection and sweep events.The results show that the buffer layer of the turbulent boundary layer has thinning tendency and logarithmic layer down-shift, the turbulence intensity and the Reynolds stress are also enhanced due to the existence of particles.The amplitude of longitudinal and vertical fluctuating velocity components, as well as that of the spanwise vorticity and Reynolds shear stress can be manipulated obviously both in ejection and sweeping events, all parameters were increased. It imply that the turbulence intensity in the near-wall region in the two burst events increase, and the momentum and energy transport strengthen for the exist of particle in the experiment.