Fluids

Fluids

FLUENT-DES-GRID

    • mimozas1
      Subscriber

      Hallo everybody!

      I am conducting a Detached Eddy Simulation of a 3D wing.

      My main focus for now is capturing cd-cl fluctuations once the wake is being set to periodical motion.

      For that reason i have encountered some thought that troubled me. I know since near the wall-boundary the simulation is like RANS, i need y+<=1 for k-omega model. But fot the LES part of the grid i am having trouble defining exactly the size of the grid. I have made a lit.review but found no solid and universal criteria for grid size. The idea i am having is defing that through experimenting-changing-re experimenting.

      If anyone has any knowledge on the field of the grid size for the LES part of the DES grid i would be very glad and thankfull to share it.

      Again thanks for your time people!

    • Rob
      Ansys Employee
      Check the courses (top of the page) as at least one covers turbulence and LES. From memory, when the LES model first came out we used to run k-e (would be k-w in your case) to get a flow field and an idea of how turbulent the system was. There may be additional guidance in the Fluent documentation and references quoted there.
    • Murari Iyengar
      Ansys Employee
      Hi mimozas1 LES requires a finer mesh than those typically used for RANS. In the DES model, based on the turbulent length scaleand grid spacing, RANS/LES model is chosen. For more information, please see the links below.
      4.16.1. Overview (ansys.com)
      10.1. Estimation of the LES Resolution Quality (ansys.com)
      13.2.2. Scale-Resolving Simulation (SRS) Models (ansys.com)


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