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Velocity Fluctuation Algorithm Large Eddy Simulation

    • Ibrahim El-Gheriani

      Hello everyone,

      I have a question regarding the significance of the velocity fluctuation algorithm for the inlet boundary in LES. Recently, I started an LES simulation and just noticed that I inadvertently left the default option, "No Perturbations," instead of selecting the recommended "Vortex Method." Unfortunately, I cannot restart the simulation due to an approaching project deadline, and LES simulations require considerable time to complete.

      Can anyone advise on the potential implications of this oversight on my simulation results? For context, I have implemented a User-Defined Function (UDF) for the velocity profile and used a precursor Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulation as a starting point for my LES.

      Any insights or suggestions would be greatly appreciated. Thank you in advance!

    • Federico Alzamora Previtali

      "No perturbations" would be suitable if the level of turbulence at your inlet is negligible compared to the rest of the flow. In this case, the velocity fluctuations at the inlet are neglected, creating a "flat" turbulent profile.

      LES models require realistic inlet conditions. If the turbulence at your inlet is important, I imagine this would impact your solution.

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