On January 15, 2019, Eric Jagers, Kyle Boddy, Joe Marsh and Dean Jackson of Driveline visited the USU Experimental Fluid Dynamics Laboratory to attempt to capture the air velocity field around a “Laminar Express” pitch. Nazmus Sakib and Andrew Smith (not pictured) took the measurements. These are our preliminary findings. Continue Reading
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Questions I Want to Answer Post #12
Some of these may not mean a lot to lay persons. I’m putting this here so I can keep my eye on the ball and in case anyone like-minded wanders by. As these questions are answered, I’ll change them to italics and link the answer to the Yes or No. Continue Reading
More about Pressure Gradients Post #11
Here’s a very nice description of transition from laminar to turbulent flow and how that is distinct from yet often correlated to boundary layer separation. This may help you better understand my description of how seams and pressure gradients interact as well as how that may lead to the Laminar Continue Reading
How a “Laminar Express” Might Work Post #10
NOTE: The conclusions drawn in this post are based on an erroneous idea about the orientation of this pitch. For the correct ball orientation, this description does not make sense. For a better explanation, see the new post Before I get started, first I want to acknowledge the influence or Rod Cross’ article on this topic. He Continue Reading
Location of a Seam Relative to Pressure Gradient Post #9
OK, this is some hardcore fluid dynamics. Hang on tight. But understanding this concept is key to understanding how seams may effect laminar/turbulent flow and boundary layer separation. As a baseball moves through the air, the pressure on the front of the ball is higher than the surrounding air, which Continue Reading
What Does Boundary Layer Mean? Post #8
A boundary layer exists whenever a fluid (liquid or gas) flows over a surface. The boundary layer is the part of the gas that feels the skin of the baseball and is thus accelerated. The concept of the boundary layer was introduced by Ludwig Prandl in 1904. He is commonly Continue Reading
PIV On Knuckleball Pitches Post #7
The “Knuckleball is thrown off the tips of the fingernails in a manner that inhibits spin (or at least when thrown with great skill). As shown in our post on 2-seamers and on one on the seam’s affect on boundary layer, the location of boundary layer separation tends toward the Continue Reading
What is PIV? Post #6
Particle Image Velocimetry (PIV) is our main measurement technique. It uses two laser sheet pulses to illuminate a slice of a flow. We add particles to the flow (theater fog, in our case), and the laser pulses illuminate these particles. Think of the lasers as a camera flash, but only Continue Reading
Effect of Seams on the Boundary Layer Post #5
Our preliminary study using high-seamed Wilson 1030 baseballs and a brutal 3-wheel machine. These results were presented at the 2018 APS DFD meeting. These results are based on velocity measurements in the air using PIV. All of these data sets were acquired in a vertical plane. We start with a smooth Continue Reading
Do seams affect trajectory?Post #4
11/29/2020. I will leave the original post unchanged below, but some of our claims here proved to me untrue, or at least more nuanced than we realized. Were I to write this today, I’d point out that seams don’t matter most of the time when the ball has no gyro Continue Reading
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