Effect of Knudsen Number, Lid Velocity and Velocity Ratio on Flow Features of Single and Double Lid Driven Cavities

Effects of Knudsen number, lid velocity and velocity ratio are investigated on the flow features of single lid driven cavity with an aspect ratio of one and double lid driven cavity of aspect ratio two. Knudsen numbers studied are ۰.۰۱(early slip regime), ۰.۱ (slip regime) and ۱ (transitional regime). Lid velocities investigated are ۱۰۰ m/s, ۲۰۰ m/s and ۵۰۰ m/s. The velocity ratios explored are ۱ and -۱. Knudsen number was found to have a huge impact on the flow rigidity. Lid velocity tends to shift the central vortex to the top left of the cavity for a cavity with aspect ratio of one and shifts the upper vortex to the top left of the cavity for a cavity with aspect ratio of two. Lid velocity does not affect the slip to a great extent on the lid. Changing the velocity ratio from ۱ to -۱ leads to the reversal of the relative vorticity in the top and bottom half of the cavity.

Keywords:

Rarefied gas dynamics , DSMC , MEMS/NEMS , OpenFOAM