(128g) Direct Numerical Simulation of Turbulent Flow Over a Surface Mounted Obstacle

Three-dimensional turbulent flow over a surface-mounted obstacle is studied as a numerical experiment that takes place in a wind tunnel. The transient Navier Stokes equations are solved directly with Galerkin finite elements. The Reynolds number defined with respect to the height of the wind tunnel is 12518. Instantaneous strealine patterns are shown that give a complete picture of the flow phenomena. Energy spectra yield the -5/3 law proposed by Kolmogorov. Mean values of velocities and and root mean square fluctuations are compared with the available experimental results. Other statistical characteristics of turbulence such as Eulerian autocorrelation coefficients, longitudinal and lateral coefficients are also computed. Finally oscillation diagrams of computed velocity fluctuations yield the chaotic behavior of turbulence. The chaotic nature of turbulence is also going to be shown in a video produced from the numerical results of the work.

All computations have been performed in the Blue Gene Supercomputer of the San Diego Supercomputing Center and the National Center for Atmospheric Research using more than thousand processors.