Results worsen as the mesh size decreases

- November 15, 2023 at 9:53 am
  
  N. M.
  Subscriber
  
  Hello everyone,
  I'm attempting to simulate the flow around a wing airfoil using a steady-state, 2D simulation. In the mesh creation, I employ edge sizing with "Number of elements" option for the airfoil edge.
  During various simulations, I've observed a potentially unusual behavior. I obtain a solution in cl and cd computation, but when I refine the mesh around the airfoil by increasing the number of elements on the airfoil edge (thus keeping y+ constant), the calculation diverges, and the solver does not reach a solution.
  Is this normal? I thought that densifying the mesh would lead to more accurate results until a certain point, beyond which the values of cl and cd computed would remain constant with the increasing mesh density.
  I hope the question is clear.
  Thank you.
  
  Nicola Menga. ????
- November 15, 2023 at 1:52 pm
  
  Federico
  Ansys Employee
  
  Yes, you should expect grid refinement to improve accuracy of results, but factors other than only cell count may come into play.
  How does your mesh quality compare between grid refinements?
  - November 16, 2023 at 12:45 pm
    
    N. M.
    Subscriber
    
    What do you mean with "Mesh quality"?
    The values of Aspect Ratio, Skewness and Orthogonal quality?
    - November 16, 2023 at 1:37 pm
      
      Federico
      Ansys Employee
      
      Yes, all of those