Fluids

Fluids

How do you calculate the drag coefficient for an object?

    • Karthik R
      Administrator
      How do you calculate the drag coefficient for an object?
    • prajput
      Ansys Employee

      You can calculate drag coefficient rearranging the drag equation. The three dimensional drag coefficient Cd is equal to

      D/(0.5*rho*A*V^2)

      for 2D problems it is Cd = D/(0.5*rho*L*V^2)

    • Karthik R
      Administrator
      Thanks @prajput for your reply! Using this equation I am getting a value of 0.38. What does this mean? as in physically?
    • prajput
      Ansys Employee

      The drag coefficient is a dimensionless number that engineers use to evaluate the aerodynamic performance of an object in motion for example a flying airplane. It basically quantifies the drag force or resistance of the flow on the object. As mentioned in the previous post, it is proportional to the magnitude of drag force. So a lower drag coefficient indicates the object is subject to a smaller aerodynamic or hydrodynamic drag. 

    • Karthik R
      Administrator
      So does it mean that having a lower drag coefficient is better?
    • Keyur Kanade
      Ansys Employee
      Yes! A low drag coefficient means that you can go faster or consume less fuel. However, higher drag coefficient it can be useful when you want to slow things down, like a parachute for drag races.
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