Lift, Drag, Magnus, Bernoulli, Tennis ball fuzz, etc.

[Trying2Learn]

TL;DR

Can someone advise me?

Hello,

My background is not fluid mechanics. Yet, I am trying, very late in life (near retirement) to understand some things, now that I have time.

I have always been confused about the qualitative descriptions about the role of dimples on golf balls and fuzz on tennis balls. Sometimes,
the explanations seem to contradict each other.

So I put together a document that (I HOPE) explains it.

Would anyone be willing to read this document (it is four pages) and let me know where I go wrong?

I am tired of being confused and in not finding any coherent explanation.

It is attached. I hope to know where I go wrong.

 

[rcgldr]

Magnus effect is normally explained by noting that the air flow over the surface that is spinning backwards stays attached longer than the air flow over the surface that is spinning forwards, resulting in the ball diverting the wake in the direction of the spin at the back of the ball, coexistent with the air exerting an equal an opposite force onto the ball.

https://en.wikipedia.org/wiki/Magnus_effect

 

[Frodo]

Years ago I read an excellent book The Physics of Ball Games by CB Daish which discussed all this and more. It analysed golf, table tennis, football, snooker, cricket etc, including Magnus effect, flow separation, centre of percussion etc.

Specialist sellers have it in stock - google the title.

 

[Baluncore]

Specialist sellers have it in stock - google the title.

The Physics of Ball Games by C B Daish.
Part 1, a more general treatment of the subject.
Part 2, the full mathematical treatment.

There are three versions listed on https://www.bookfinder.com
1972, Hardcover, 180 pages. ISBN 9780340053997 Pub; English Universities Press.
1972, Part 1 only. Hardcover, ISBN 9780340167229 Pub; English Universities Press.
1981. Parts unspecified. Softcover, ISBN 9780340270622 Pub; Hodder & Stoughton.

 

[Frodo]

Also see The physics of golf authored by A Raymond Penner, Physics Department, Malaspina University-College, Nanaimo, British Columbia, V9R 5S5, Canada available at http://raypenner.com/physicsofgolf.html and http://stacks.iop.org/rp/66/131

Abstract

An overview of the application of physics to the game of golf is given. The golf swing is modeled as a double pendulum. This model and its variations have been used extensively by researchers in determining the effect that various swing parameters have on clubhead speed. These results as well as examples of three-link models are discussed. Kinematic and kinetic measurements taken on the recorded downswings of golfers as well as force measurements are reviewed. These measurements highlight differences between the swings of skilled and unskilled golfers.

Several aspects of the behaviour of a golf ball are examined. Measurements and models of the impact of golf balls with barriers are reviewed. Such measurements have allowed researchers to determine the effect that different golf ball constructions have on their launch parameters. The launch parameters determine not only the length of the golf shot but also the behaviour of the golf ball on impact with the turf. The effect of dimples on the aerodynamics of a golf ball and the length of the golf shot is discussed. Models of the bounce and roll of a golf ball after impact with the turf as well as models of the motion of a putted ball are presented.

Researchers have measured and modeled the behaviour of both the shaft and the clubhead during the downswing and at impact. The effect that clubhead mass and loft as well as the shaft length and mass have on the length of a golf shot are considered. Models and measurements of the flexing of the shaft as well as research into the flexing of the clubface and the effects of its surface roughness are presented. An important consideration in clubhead design is its behaviour during off-centre impacts. In line with this, the effects that the curvature of a clubface and the moments of inertia of the clubhead have on the launch parameters and trajectory of an off-centred impacted golf ball are examined.

 

[Trying2Learn]

Thank you everyone.

Normally, I say that right away. Unfortunately, surgery intervened. I am out, home and recovering well. Sorry about not thanking every one.