(334b) Investigation on Particle Clustering in Turbulent Channel Flow Using Large Eddy Simulations (LES)

Particle-laden turbulent flows are prevalent in natural phenomena such as sedimentation in rivers, sandstorm, cloud formation and have applications in many industrial processes like chemical reactors, pneumatic conveying of solids, gas scrubbers. Particle response to the fluid flow depends on particle inertia, the ratio of particle size to the underlying fluid scales, etc. Turbophoresis and particle clustering causes higher local concentration of particles which leads to an increase in the probability of particle collisions and flow modification. The effect of Stokes number on particle clustering has been studied by various authors for particle-laden turbulent flow. However, the effect of other parameters such as Reynolds number and mass loading on particle clustering has not been explored in detail. In the present study, large eddy simulations are performed for vertical channel flows at different Reynolds numbers, Stokes numbers, and particle volume fractions. The preferential concentration of particles in the flow is studied by implementing the voronoi tessellation method at different wall-normal locations. Probability density functions (PDF) of cluster area for LES are found to be in good agreement with Direct Numerical Simulations. The probability for clusters to have larger area decreases for higher particle loading in the channel. PDFs of cluster area and particle concentration are used to enhance our understanding of the effect of flow parameters on cluster dynamics.