Department of Aerospace Engineering, Centre of Excellence in Aerospace Systems, Sharif University of Technology, Tehran, Iran
Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, Iran
In this study, we intend to improve the mixing performance of a nanoscale mixer using the throttling idea. The study is conducted at a Knudsen number of 0.12, which corresponds to the transitional flow regime. Therefore, we have chosen the DSMC method to perform reliable numerical simulations. We consider a number of different throttles with various widths and shapes to enrich our study and to explore a wider range of their influences on the mixing evolution. We choose a linear converging-diverging nozzle profile, an arced converging-diverging nozzle profile, and a sudden contraction-expansion configuration as our throttle shapes. The results show that both the mixing length and the mass flow rate decrease as the throttle widths decrease.However, the throttle width decrease plays more effective role in reducing the mixing length than the mass flow rate decrease. Evaluating the results of three chosen throttle shapes, we conclude that the arced nozzle and sudden contraction-expansion shapes would result in less mixing length and mass flow rate magnitudes; although the reductions are more pronounced for the latter shape. We also conclude that the throttle shape affects the mixing length reduction more seriously than the mass flow rate reduction.