Study On Simulation Of Air Flow And Particle Deposition Around In-line Circular And Square Arrays

The three-dimensional flow around a building is simplified to the two-dimensional flow around a circle/square column,and the wake vortex and particle motion in the two-dimensional building flow field are studied without considering the end effect.The wake vortex formed by in-line columns,as well as the particle flow,distribution and deposition,were simulated and calculated by the Large Eddy Simulation（LES）method in the Reynolds（Re）number range from 100 to 700.Based on the velocity analytical solution of the fully developed laminar flow in a three-dimensional square cavity,the two-dimensional fully developed laminar flow inlet velocity udf is solved and defined.The vortex shedding and boundary layer separation were described,the particle movement in the wake vortex and deposition on the columns summarized,and the relationship between particle distribution and vortex street analyzed.After several times boundary layer separations,the phenomenon of periodic vortex shedding is formed,and the small vortices merge into a periodic large vortex continuously.When the Reynolds number increases,the intensity of the small vortex behind the cylinder and the large vortex in the wake show a higher trend,the drag coefficient（C_D）number of the cylinder decreases and the Strouhal(S_tr)number increases.The particles released from the inlet follow the streamlines.The smaller the particle diameter,the better the followability and the stronger the diffusion of particles.Regardless of whether it is a row of circular or square columns,deposition rate on the wall of the first column is the largest.