How Surface Roughness and Angular Velocity Affect Cl

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Transcript of How Surface Roughness and Angular Velocity Affect Cl
Introduction
A common study in fluids is that of lift and drag. For spheres, we learned that the rotation of the sphere affects its lift and drag coefficients. This occurrence is commonly known as the Magnus Effect. The following video explains what the Magnus Effect is:
Research
After doing some research, we found out that surface roughness also plays a part when determining the coefficient of lift, as described by our textbook:
“Although the drag coefficient is fairly independent of the rate of rotation, the lift coefficient is strongly dependent on it. In addition, both Cl and Cd are dependent on the roughness of the surface.”
Munson, Fundamentals of Fluid Mechanics
Previous Research
The current research shown in the graph is for a smooth sphere. This correlates the coefficient of lift with a nondimensional number involving the angular velocity.
Results
By varying the surface roughness and angular velocity of the sphere, we obtained the following results:
As can be seen, there appears to beonly minor differences in the coefficient of lift.
Matlab GUI
With the results, we made a Matlab GUI that fitted a curve to the points and allows the user to enter a roughness and angular velocity to find out the coefficient of lift!
You can find this calculator in Matlab’s file exchange.Search: Surface Roughness, Angular Velocity, or Coefficient of Lift.