Direct numerical simulation (DNS) of turbulent channels at higher Reynolds numbers and in larger computational domains
|Scientific Discipline||Fluid Mechanics|
|Principal Investigator(s)||Javier Jiménez Sendín|
|Leading Institution||School of Aeronautics, Universidad Politécnica de Madrid, Spain|
|DEISA Home Site||BSC|
Project summary and results
Using direct numerical simulation (DNS) of turbulent channels at higher Reynolds numbers and in larger computational domains than those available up to now, we study the interaction between the large scales of wall turbulence away from the wall, and the small scales near the wall. The problem is not just of scientific interest. Wall-bounded turbulence is the interface between the ambient fluid, water or air, and moving vehicles, and between flows and pipes and channels. The large scales, for example, play an important role in the dispersion of chemical agents in the atmosphere, and more than half of the friction drag in vehicles resides in the near-wall and intermediate layers The program code is based on a previous versions developed by our group during the past fifteen years, and broadly follows the standard spectral code developed at the end of the 1980s by groups at Goettingen and at NASA Ames. It is written in C and Fortran, and is parallelized using MPI, with an excellent speed-up. This simulation uses a grid of Nx = 6144, Ny = 633, Nz = 4608 (2 x 1010 points).
This was a very costly initiative. The code ran for about 6.000.000 CPUHours, 800.000 of them assigned trough a DEISA project. The MareNostrum facility became the optimal platform to run this grand Challenge simulation because of the project's computational needs, together with the large amount of memory required per process and the huge amount of data interchanged, roughly 122 EB. It was a challenge for the support team of MareNostrum because of the simulation's size. MareNostrum is a facility available to the global scientific community.
Spanwise component of vorticity. Visit http://torroja.dmt.upm.es/~sergio for this and other pictures.