A place to learn how air flows over a baseball.

Posts are listed in reverse chronological order. Obsolete items are not linked but are still available.

Key to Table of Contents:

Background Material,


Movie or Presentation

Science Post


Diagnosing and Modeling SSW pitches

How to Tell if You Threw a SSW Pitch, Sinker/Changeup Edition

Killing Laminar Flow

Case Study: Good and Bad Discoballs

Using Baseball Seams to Create Break

What Magnus Effect Looks Like

Relationship between Orientation and gyro for Seam-Shifted-Wake pitches

Describing Ball Orientation

How to Use the Looper and Scuffball

A Zero-Gyro Seam Shifted Wake Pitch. The Looper

Rapsodo 1.0 and Seam Shifted Wake Pitches

The State of Baseball Aerodynamics

Magnus Models and Constant Acceleration Assumptions

How to Legally Scuff a Baseball

Scuffed Baseballs

Toward a Better Pitch Tracker

Disco Ball Changeup Experiment

Seam-Shifted Wake Axis

2019 in Review

How Does Pitching Work?

Magnus Effect,  Seams and Roughness

My APS DFD presentation on the Fluid Dynamics of Seam Shifted Wakes

The Non-Centered Pill Baseball Drag Theory

The Seam Shifted Wake

Effect of Seam Height on Wake of MLB Baseballs

3D Explanation of Laminar Express

Seam Height ball-to-ball/year-to-year Variation

Kelvin-Helmholtz Instabilities and Baseballs, Jets, the Atmosphere, and Jupiter

Prediction of Flow Pattern of Laminar Express Over a Full Rotation

My Latest Thoughts on Laminar Express: Post 29

Primer on Understanding Our Results

Saberseminar 2019 Presentation: What do Baseball Seams do to a Ball in Flight?

Ball Smoothness, Roundness and Drag

Baseball Rubbing Mud and its Effect on Roughness

Baseball Roughness Effect on Laminar Separation:

Laminar and Turbulent Boundary Layer Separation on New MLB balls

First PIV Measurements on MLB Balls

Baseball Drag Crisis Post

Addendum: Cricket Balls and CFD on Baseballs Post

Why I don’t want to talk about cricket balls, wind tunnel studies or CFD

The theory of Seam-Controlled Wakes

A different idea on the “Laminar Express”

A Complete Description of the Laminar Express

What we still don’t know about Laminar Express

Driveline Laminar Express Study

Questions I Want to Answer Post

More about Pressure Gradients Post

How a “Laminar Express” Might Work Post

Location of a Seam Relative to Pressure Gradient

What Does Boundary Layer Mean?

PIV On Knuckleball Pitches

What is PIV?

Effect of Seams on the Boundary Layer

Do seams affect trajectory?

Attempt using a machine

Why am I interested in Baseball Drag?

Previous study of 2 vs 4 seam pitches