Corner Flow Circulation at Highly Rarefied Conditions and Its Correlation with Mass Transport in Microchannels

The talk presents two recent studies examining the emergence of corner-flow circulation in confined geometries at highly rarefied conditions, where the characteristic length scale is comparable to the molecular mean free path of the gas.

The first study investigates gas flow inside an open triangular cavity subject to external shear flow in the free- and near-free-molecular flow regimes. Analytical solutions of the collisionless Boltzmann equation reveal the anomalous formation of multiple recirculation zones even in the absence of molecular interactions. The analysis demonstrates how vortex topology depends on the corner angle and wall accommodation properties, establishing a direct connection between microscopic particle kinematics and macroscopic circulation patterns. We additionally discuss ongoing work examining the effect of weak intermolecular interactions at finite yet high Knudsen numbers on the vortical structures. The analytical predictions are validated numerically via the direct simulation Monte Carlo (DSMC) method, showing excellent agreement.

The second study considers pressure-driven gas flow through a bent microchannel at highly rarefied conditions. The free-molecular mass flow rate is mapped analytically as a function of the channel bent angle and length. Notably, oscillatory non-monotonic behavior is revealed and rationalized, associated with vortex formation and flow detachment at the channel corner.

The seminar will be given by Din Ben Adva the 2026 winner of the Prize in Memory of Prof. Shmuel and Noemi Merhav