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Laminar Express

May 15, 2008
580
28
Cape Cod Mass.
This is a nickname that baseball uses for breaking pitches that don't depend on the Magnus Effect for their breaking force. The idea seems to be that on 2 seam pitches there is an imbalance in the wake behind the ball that can cause a pitch to break. The air flow that surrounds a ball can be of two types, laminar (smooth) or turbulent. The amount of force that is associated with each type of flow is different. Seams can change laminar flow to turbulent and create an imbalance that causes a ball to break. So seam orientation and axis of spin are the major factors, RPM's don't count for much. As to whether or not these pitches use bullet spin (gyro in baseball) depends on how you define bullet spin. If the horizontal axis of spin is half way between top and bullet what kind of spin is it.

Here is a link to an explanation of how laminar flow can cause a pitch to break. It is very technical and at times made my head hurt but eventually I made sense of it. The videos of the breaking pitches are incredible to look at. The pictures of balls in the illustrations are from an overhead view so you are looking at the wakes on the sides of the ball, not on the top and bottom, that had me confused for a while.

 

pattar

Clueless..
Jun 8, 2016
3,901
113
This is a nickname that baseball uses for breaking pitches that don't depend on the Magnus Effect for their breaking force. The idea seems to be that on 2 seam pitches there is an imbalance in the wake behind the ball that can cause a pitch to break. The air flow that surrounds a ball can be of two types, laminar (smooth) or turbulent. The amount of force that is associated with each type of flow is different. Seams can change laminar flow to turbulent and create an imbalance that causes a ball to break. So seam orientation and axis of spin are the major factors, RPM's don't count for much. As to whether or not these pitches use bullet spin (gyro in baseball) depends on how you define bullet spin. If the horizontal axis of spin is half way between top and bullet what kind of spin is it.

Here is a link to an explanation of how laminar flow can cause a pitch to break. It is very technical and at times made my head hurt but eventually I made sense of it. The videos of the breaking pitches are incredible to look at. The pictures of balls in the illustrations are from an overhead view so you are looking at the wakes on the sides of the ball, not on the top and bottom, that had me confused for a while.

The point that he was trying to make was that it wasn't the transition from laminar to turbulent flow (he claims that data shows that the boundary layer is turbulent already for the typical speeds of thrown baseballs hence the seams don't actually cause any transition to turbulence) that was causing balls with gyro spin to break towards third but instead that the location of the seam (on the third base side) which is the dominating factor. The reason for this is that if the separation points on the 3rd and 1st base sides do not line up, the resulting pressure distribution on the ball will result in a net force towards the 3rd base side (for the example shown).In the case of ball with seams, for a range of gyro spin rates(Figure 5 is a depiction of two possible cases for this range), the points of separation on the third and first base sides of the ball are due to the seams.

The physics is the same as stalled flow over wings in an airplane. As the wing angle of attack increases at some point the lift force (force in the opposite direction of the weight of the airplane) drastically decreases due to the location of the flow separation point moving in the direction of the airplane motion. This causes the resulting pressure distribution around the airfoil to be such that the resulting lift force decreases significantly. For the baseball/softball case the lift force equivalent would be the net force towards 3rd base.
 
Last edited:
May 6, 2015
1,195
83
The point that he was trying to make was that it wasn't the transition from laminar to turbulent flow (he claims that data shows that the boundary layer is turbulent already for the typical speeds of thrown baseballs hence the seams don't actually cause any transition to turbulence) that was causing balls with gyro spin to break towards third but instead that the location of the seam (on the third base side) which is the dominating factor. The reason for this is that if the separation points on the 3rd and 1st base sides do not line up, the resulting pressure distribution on the ball will result in a net force towards the 3rd base side (for the example shown).In the case of ball with seams, for a range of gyro spin rates(Figure 5 is a depiction of two possible cases for this range), the points of separation on the third and first base sides of the ball are due to the seams.

The physics is the same as stalled flow over wings in an airplane. As the wing angle of attack increases at some point the lift force (force in the opposite direction of the weight of the airplane) drastically decreases due to the location of the flow separation point moving in the direction of the airplane motion. This causes the resulting pressure distribution around the airfoil to be such that the resulting lift force decreases significantly. For the baseball/softball case the lift force equivalent would be the net force towards 3rd base.
yeah, what he said! ;)
 

pattar

Clueless..
Jun 8, 2016
3,901
113
I don't get it. But while most of what I read on the interwebs makes me feel dumber for having been exposed to it, this made me feel a little smarter. Thanks, pattar.
Cliff Notes
The movement of a ball or an airplane ultimately comes down to the resulting forces in each coordinate direction. Separation points on a ball surface or a wing surface effect the pressure distribution on said surface which in turn effects the resulting forces. For a range of gyro spin axes, the location of the seams on a ball effects separation points which in turn result in a net force in 3rd base direction (for the example provided) hence movement towards a RH hitter.
End of Cliff Notes


Additional Information:


Different points, on the third and first base sides, of the transition from a laminar boundary layer (flow nearest to the surface) to a turbulent boundary layer can also cause a net force. However the author claims that the boundary layer is already turbulent before it encounters any seams on either side of the ball and hence this isn't what causes a net force, e.g. movement, towards a RH hitter.

The stall flow example really wasn't really anything different (the physics is same for stall or non-stall flow) but instead just an extreme example of what moving a separation point does to the resulting force. In stalled flow for an airplane the flow separation point causes the lift force to decrease to a point where it no longer balances the weight and the plane will drop..you can see this in those airshows where you see the planes climb at a steep angle of attack and then all of a sudden drop since the resulting force on the wing is now in the direction of gravity.
 
Last edited:
May 30, 2013
1,293
63
Binghamton, NY
Cliff Notes Version:

The movement of a ball or an airplane ultimately comes down to the resulting forces in each coordinate direction. Separation points on a ball surface or a wing surface effect the pressure distribution on said surface which in turn effects the resulting forces. For a range of gyro spin axes, the location of the seams on a ball effects separation points which in turn result in a net force in 3rd base direction (for the example provided) hence movement towards a RH hitter....
 

pattar

Clueless..
Jun 8, 2016
3,901
113
Bunch of wiseguys around here :LOL: I didn't bring up the topic, just trying to interpret the article correctly for anybody interested :)
 
May 6, 2015
1,195
83
AN
Bunch of wiseguys around here :LOL: I didn't bring up the topic, just trying to interpret the article correctly for anybody interested :)
and it is greatly appreciated pattar! just was meant to be a little self deprecating humor!
 
Mar 20, 2015
112
18
The point that he was trying to make was that it wasn't the transition from laminar to turbulent flow (he claims that data shows that the boundary layer is turbulent already for the typical speeds of thrown baseballs hence the seams don't actually cause any transition to turbulence) that was causing balls with gyro spin to break towards third but instead that the location of the seam (on the third base side) which is the dominating factor. The reason for this is that if the separation points on the 3rd and 1st base sides do not line up, the resulting pressure distribution on the ball will result in a net force towards the 3rd base side (for the example shown).In the case of ball with seams, for a range of gyro spin rates(Figure 5 is a depiction of two possible cases for this range), the points of separation on the third and first base sides of the ball are due to the seams.

The physics is the same as stalled flow over wings in an airplane. As the wing angle of attack increases at some point the lift force (force in the opposite direction of the weight of the airplane) drastically decreases due to the location of the flow separation point moving in the direction of the airplane motion. This causes the resulting pressure distribution around the airfoil to be such that the resulting lift force decreases significantly. For the baseball/softball case the lift force equivalent would be the net force towards 3rd base.
Are you saying that the seam orientation on the third base side effectively creates and air foil so the pressure differential similar to the lift on an airplane wing moves the ball toward third base? The airflow diagram on Figure 3 vaguely looks like this.
 

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