Here, flow in the gap between periodically structured surfaces is studied when the reflection symmetry along the channel axis is broken. A series of triangular fins with alternating specular and diffuse walls are placed on the cold bottom wall while the top wall is straight and kept at a higher temperature. The flow induction mechanism in this geometry is shown to be the same as the Crookes radiometer process. Here, we consider a mixture of two molecules and focus on the gas separation performance of the pump. Direct simulation Monte Carlo (DSMC) simulations are performed to investigate separation performance over a broad range of Knudsen numbers. Our simulation results reveal that the proposed geometry could efficiently separate light and heavy gas particles.

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