Molecular-level simulations of turbulence via the direct simulation Monte Carlo method

In the last decade, the advent of exascale computing platforms has enabled molecular-level investigations of turbulence using the direct simulation Monte Carlo method. This talk highlights insights gained from this molecular-level approach, including the demonstration that, beginning at a length scale comparable to the Kolmogorov scale, the rapid decay of the energy spectrum observed in deterministic Navier-Stokes simulations is replaced by quadratic growth due to thermal fluctuations. Importantly, the effects of thermal fluctuations become dominant at length scales much larger than the molecular mean free path, in contrast to conventional arguments for the validity of the deterministic Navier-Stokes equations in this regime.

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.