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Direct numerical simulation of turbulent flows.

Short description

A relevant fraction of the energy spent in transportation is lost in a thin layer where the surrounding fluid contacts the surface of the vehicle, called boundary layer. That thin layer, where the fluid is in a turbulent state, is still not fully understood. Describing the structure of the turbulent wall bounded flows, particularly boundary layers, but also pipes and other internal flows, is essential to improve the turbulence models and sub-grid approximation for large-eddy simulations, that are a key ingredient in most industrial CFD applications.

OpenTBL is a fast, highly scalable, and memory efficient code that uses a high resolution numerical scheme to simulate a turbulent boundary layer with a range of possible configurations. This code has provided the largest simulation of a zero-pressure-gradient boundary layer, that is publicly available to researchers and engineers.

OpenTBLRepresentation of instantaneous streamwise velocity coherent structures. The represented domain is 5 times shorter in the x direction, and twice narrower in the z direction than the complete simulation. The arrow points in the direction of the flow.


  • 458,752 cores (1,835,008 compute threads) on BlueGene/Q (JUQUEEN)
  • 32,768 cores on BlueGene/P
  • 8,192 cores on Cray XC-6
  • 4,096 cores on x86-64

Performance of OpenTBL on JUQUEEN(left) Efficiency for all the cases tested on JUQUEEN. Each color represents a different test, circles correspond to strong scaling tests, and triangles to weak scaling tests. (right) Performance measured in degrees of freedom (size of the problem) per second of wall time per core. The black line with squares corresponds to the tests performed on a BG/P with the same implementation.

Programming language and model

  • Fortran 2003
  • Hybrid parallelism (MPI + OpenMP)
  • I/O in parallel HDF5

Tested on platforms

  • BlueGene/Q
  • BlueGene/P
  • Cray XC-6
  • x86-64

Application developers and contributors

  • Javier Jiménez
  • Juan A. Sillero
  • Guillem Borrell
  • Mark P. Simens (Previous version)
  • Siwei Dong (Tests in JUQUEEN)


Javier Jiménez
ETSI Aeronáutico
Universidad Politécnica de Madrid
Pza Cardenal Cisneros 3
28040 Madrid