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Negative components of lift and drag

    • c2087845
      Subscriber

      I am trying to run simulations for lift and drag at different angles of attack for an aerofoil. When inputting the lift force coefficients I enter a negative number, this causes an error saying "floating point exception". However I have checked and these values are supposed to be negative. I am using the student edition so im not sure if this is a limitation of that but any help is much appreciated

    • Rob
      Forum Moderator

      Where are you entering a negative number? 

    • c2087845
      Subscriber

      When i enter the x component of lift, the value is negative at the angle of attack I am using

    • c2087845
      Subscriber

      for some reason it works for my initial setup and solution on fluent but not for the duplicates I am creating for different angles of attack

    • Rob
      Forum Moderator

      How are you adding the lift component, or do you mean the vector definition? Pictures will help. 

    • c2087845
      Subscriber

      yes i mean the vector

    • Rob
      Forum Moderator

      That shouldn't have any effect on the solver stability, it's just to report the force components. 

      If the model is failing, check the mesh and boundary settings are suitable: the NACA airfoil has been used as a tutorial/help video in Fluent and also in the Learning content on here. 

    • c2087845
      Subscriber

      is there a way to quikcly fix the sharp trailing edge in my aerofoil geometry as I believe this may be an isse

    • Rob
      Forum Moderator

      There are a couple of approaches. Trim the end to give a "blunt" trailing edge or break the geometry to extend the mesh from the trailing edge through the domain.

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