1. The Knuckleball Problem

2. Presented by:
Patrick Figaro
Lino Gutierrez
Jacob Hedden
Lan Nguyen

3. Introduction Important topics related to explaining the knuckleball
Turbulent flow vs. Laminar Flow
Reynold’s Number
Friction Factor and Drag force

4. Problem Statement
A knuckleball is a type of baseball pitch that is thrown without any spin on the ball. The seams cause flow transitions over the spherical surface so that the baseball (diameter D=3 in) moves in an unpredictable manner in response to varying drag and lift. If the best speed to throw a knuckleball is about 85 mph, determine the Reynold’s number for transition. Compare your value to the data in chapter 9

5. Solution
Given:
v= 85 mph
D= 3 in
85 mph
3 in.

6. Find: Assumptions: Plan: The Reynold’s number T=80°F P=1 atm
rAir= lbm/ft3
Plan:
Use Fig to find viscosity
Then use Re= (rvD)/m

7. Solution:
Unit Conversions

8. From Fig 3.4.3

9. For a sphere,

10. Discussion: