Characterization of Small-scale Turbulence by Direct Numerical Simulation

Direct Numerical Simulation (DNS) is the numerical solution of the exact three-dimensional, time-dependent Navier-Stokes equations, governing fluid motion. Results from DNS of turbulent homogeneous shear flow provide detailed information on the structure and dynamics of small-scale turbulence.

This image characterizes and depicts small-scale structure in terms of the relative significance of rotational versus straining motion. The red areas correspond to rotation-dominated (high vorticity) regions which concentrate into tube-like structures. The green regions are those with comparable rotation and strain which tend to form sheets and surround the tube-like structures. The blue areas correspond to strain-dominated regions which indicate locally high energy dissipation.

The tubes are oriented at approximately 30-45 degrees from the horizontal: this is the effect of the shear flow.

Credits:

Peter Diamessis, Keiko Nomura
Department of Mechanical and Aerospace Engineering, University of California, San Diego

G. Johnson, N. Bordes
San Diego Supercomputer Center, University of California, San Diego