Lift coefficient

- July 31, 2020 at 2:23 pm
  
  prajput
  Ansys Employee
  
  Can the Lift coefficient be negative? ?
- July 31, 2020 at 2:24 pm
  
  Keyur Kanade
  Ansys Employee
  
  Hi @prajput ,
  The lift coefficient is a non-dimensional value that is commonly used to analyze the performance of a wing or its section (airfoil). The lift coefficient can be calculated as:
  Cl = L / (q * S) for a 3D body
  cl = L / (q * c) for a 2D body
  where:
  L is the lift force
  q = (1/2)*rho*V^2 is the dynamic pressure
  S is the reference surface (for wings the plan-view surface)
  c is the reference length (for airfoils the chord)
  Now analyzing this equation, we can see that area, density and velocity cant be negative. So for the Lift coefficient to be negative the lift should be negative.