Fluids

Fluids

What is the signification of a very small Y+ value ?

    • manelaero2020
      Subscriber

      Hi everyone 🙂

      I am simulating airflow over a wing. The flow is turbulent, so I have put a 6 inflation layer near the wall, the height of the first is 4 micrometers with a progression rate of 1.1. 

      My problem is the next : 

      The value of the contours of Y+ is minimal (order of e-10)  

      What is the significance of such a small Y+? Do I have well resolved my flow near the wall or is there a problem somewhere? 

      As a remark, the computation has well converged ( residual of e-8 reached), and the lift coefficient curve has reached a constant value (plateau) at the end of the computation 

      Thank you a lot

      I have used Fensap for the aerodynamic part of the computation ( the equivalent of fluent) / Turbulence model is spalart Allmaras 

    • Danica
      Ansys Employee

      Hi,

      Although the Y+ value can be useful in defining the height of the first cell next to the wall, the whole boundary layer needs to be refined appropriately for accurate results so it's important to also take this into account. Have a look at the response other thread that you have posted: questions about inflation layers /turbulence (ansys.com)

       

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