Unable to get accurate lift results in 3d airfoil simulation of NACA 0012h

- July 10, 2025 at 11:11 pm
  
  aryaman.sudhir
  Subscriber
  
  I am simulating the Naca 0012h airfoil at many AOAs, for now just 10 degrees. I am simulating both lift and drag, and getting the cl and cd from those values. However my Cl and Cd values are way of, i believe my Cl should be 1.2, however I am getting a value of .2. My fluid velocity is 30m/s, chord is 1m, and winspan is .5, however I am using symmetry. The lift value I am getting is around 27-29N, and with symmetry that makes 54-58N, which results in a low Cl. I am new to Ansys, and I have been looking at videos online to find different ways I can make my simulation better, but everytime I do change something, I still get the same lift values, I have tried Spalart alIarmas, Transition SSt, with y+ of around 1. appreciate any help!!.
  
  These are my meshes
- July 11, 2025 at 9:10 am
  
  Rob
  Forum Moderator
  
  Have a careful look at how the coefficients are defined. Then review the NACA tutorial/example in Fluent's Help to understand what you didn't set and how to alter those values. What are the outer surface boundary conditions?
- July 11, 2025 at 4:28 pm
  
  aryaman.sudhir
  Subscriber
  
  Dear Rob,
  My boundary conditions are: inlet for the front which is velocity, outlet, in the back which is pressure, and then the side with the airfoil as symmetry, and the top, bottom, and other side wall as wall. I just watched another video, and saw the person make all the walls, top bottom, and side, as symmetry, so I will try that now. Thank you for your help !!
- July 11, 2025 at 5:27 pm
  
  aryaman.sudhir
  Subscriber
  
  So my previous attempt did not work, however i tried again with transition SST, and got a much higher lift force of 56 N, with symmetry so total would be 112N. However this results in a Cl of .4, which is still less than half of what this should be, I read that for these types of tests done by actual organizations, the wings span the entire domain, so i will try that next.
- July 14, 2025 at 8:40 am
  
  Rob
  Forum Moderator
  
  Also look at the pressure on the top and bottom surfaces. You may need to adjust the range to see a peak somewhere around the blades. Then read up on wind tunnels and why they're calibrated.