Thermal-fluctuation-induced vortex shedding behind a circular cylinder

We examine the role played by thermal molecular fluctuations near the critical Reynolds number Re_c for the onset of vortex shedding behind a circular cylinder. Using the direct simulation Monte Carlo (DSMC) method, we show that molecular fluctuations exhibit nontrivial spatiotemporal correlations even far below Re_c. As Re_c is approached from below, the fluctuation amplitude increases dramatically until macroscopic vortex shedding is established. These results are consistent with previous observations of the onset of convection rolls in Rayleigh-Bénard convection and show that thermal fluctuations can also play a significant role in the onset of instabilities in open shear flows.

This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.