Collimation of Nanoparticles Inside the Single Aerodynamic Lenses with Slip Flow on Wall and Diluted Flow

Collimate beam in aerodynamic lenses are used widely for aerosol measuring. With passage of aerosol from inside an aerodynamic lens system، collimated particles beam forms. In order to evaluate the performance of an aerodynamic lens and to determine the quality of particle focus with various size and density in slip and continuous flow regime، particle-gas numerical analysis is used. Initially، compressible gas flow within aerodynamic lens with slip boundary condition on the wall was numerically analyzed using FLUENT software. Boundary condition for slip have been forced with the possibility of user programming in above software. In this case، using a repeat method، the speed of gas flow on the walls proportional to shear stress was set and this was continued until complete convergence. After convergence of the above procedure and solving gas flow in slip regime، uniform distribution of particles was injected into aerodynamic lens system and then the particles motion was analyzed by a Lagrangian method. Also، it was assumed that the flow on particles be slip. In these conditions، one of the forces acted on the particles is Stokes drag with variable Cunningham coefficient. By this method، the effect of slip on the drag coefficient and Brownian force were modeled. Solution process was assumed one way and we ignored the effects of particles on each other and on fluid flow.