Ball tampering, should the rules be relaxed?

What's buzzing in the world of cricket....

Re: Ball tampering, should the rules be relaxed?

Postby sussexpob » Fri Jun 14, 2013 3:06 pm

DeltaAlpha wrote:
SaintPowelly wrote:Bailey didn't actually accused England of tampering.

He was asked a direct question about if he was surprised how quickly they got it to reverse swing.

So far as I'm aware, there's no theoretical reason why the ball shouldn't reverse swing right from ball #1. It's just easier to do when one side's got the shine off it.


How so, DA?
2010 French Open fantasy league guru 2010 Wimbledon fantasy league guru 2014 Masters golf fantasy guru 2015 Players Championship FL Guru 2016 Masters Golf Fantasy Guru

And a hat and bra to you too, my good sirs!
sussexpob
 
Posts: 35322
Joined: Sun Jan 24, 2010 5:14 pm
Location: Asker, Norway
Team(s) Supported: Sussex and England Cricket, Vålerenga Fotball/FC Barcelona/Seagulls! ....
England and Norway at everything else

Re: Ball tampering, should the rules be relaxed?

Postby hopeforthebest » Fri Jun 14, 2013 3:12 pm

SaintPowelly wrote:
hopeforthebest wrote:
SaintPowelly wrote:Bailey didn't actually accused England of tampering.

He was asked a direct question about if he was surprised how quickly they got it to reverse swing.


The Aussie chairman of selectors came out and didn't agree with Bailey's remarks so he thought so.


Bailey said he was unsure how they got swing, and Australia didnt and the other game played at the same venue got no swing.

He never said he thought England cheated.


In the same way that Clinton admitted smoking pot but didn't inhale.
Work expands to fill the time available, so why do today what can be put off until tomorrow.


2017 West Indies v Pakistan ODI FL Guru
2016 Bangladesh v England Combined FL Guru
2016 India v New Zealand ODI FL Guru
2015 India v South Africa ODI FL guru.
2013 Ashes fantasy prediction guru
2013 NZ in England combined FL guru.
hopeforthebest
 
Posts: 15058
Joined: Thu Jun 02, 2011 12:50 pm
Location: The Netherlands
Team(s) Supported: Warwickshire and England

Re: Ball tampering, should the rules be relaxed?

Postby DeltaAlpha » Fri Jun 14, 2013 3:19 pm

It's not easy to explain in a single post, sussex, but, basically it depends on how the 'boundary layers' - the layers of air closest to the ball - behave. These layers will separate from the ball at some point, and the key to swing bowling is to get the one on one side to separate earlier than the one on the other side.

With reverse swing, the boundary layer on the off side (the side to which the seam's pointing) is separated by interaction with the seam - that's why a prominent seam helps. The one on the leg side will separate some time after it has passed the centre of the ball - how much after depends on how rough that side is; the rougher, the later, within reason.

If you can visualise that, you'll see that the layer on the leg side separates later than the one on the off side - even if the leg side's shiny - and this deflects the air flow to the off side. By the conservation of momentum, the ball will then tend to move to the leg side.

I did a thread on swing bowling soon after I joined CMS - I'll dig it up if anyone's interested.
Last edited by DeltaAlpha on Fri Jun 14, 2013 3:25 pm, edited 1 time in total.
2011-12 CMS winter chess champion
2011 CMS spring chess champion
DeltaAlpha
 
Posts: 6277
Joined: Sat Dec 05, 2009 3:49 pm
Location: Lancashire
Team(s) Supported: England

Re: Ball tampering, should the rules be relaxed?

Postby sussexpob » Fri Jun 14, 2013 3:23 pm

DeltaAlpha wrote:It's not easy to explain in a single post, sussex, but, basically it depends on how the 'boundary layers' - the layers of air closest to the ball - behave. These layers will separate from the ball at some point, and the key to swing bowling is to get the one on one side to separate earlier than the one on the other side.

With reverse swing, the boundary layer on the off side (the side to which the seam's pointing) is separated by interaction with the seam - that's why a prominent seam helps. The one on the leg side will separate some time after it has passed the centre of the ball - how much after depends on how rough that side is; the rougher, the later, within reason.

If you can visualise that, you'll see that the layer on the leg side separates later than the one on the off side, and this deflects the air flow to the off side. By the conservation of momentum, the ball will then tend to move to the leg side.



What causes a new ball to act differently? I mean under what conditions would one side separate against normal conditions?
2010 French Open fantasy league guru 2010 Wimbledon fantasy league guru 2014 Masters golf fantasy guru 2015 Players Championship FL Guru 2016 Masters Golf Fantasy Guru

And a hat and bra to you too, my good sirs!
sussexpob
 
Posts: 35322
Joined: Sun Jan 24, 2010 5:14 pm
Location: Asker, Norway
Team(s) Supported: Sussex and England Cricket, Vålerenga Fotball/FC Barcelona/Seagulls! ....
England and Norway at everything else

Re: Ball tampering, should the rules be relaxed?

Postby DeltaAlpha » Fri Jun 14, 2013 3:28 pm

It's not that a new ball acts differently, it's that it's more difficult to get it to act so as to get reverse, if you see what I mean. The margins are much smaller because the boundary layer on the leg side separates earlier than with an old ball. But it's still theoretically possible.
2011-12 CMS winter chess champion
2011 CMS spring chess champion
DeltaAlpha
 
Posts: 6277
Joined: Sat Dec 05, 2009 3:49 pm
Location: Lancashire
Team(s) Supported: England

Re: Ball tampering, should the rules be relaxed?

Postby sussexpob » Fri Jun 14, 2013 3:33 pm

DeltaAlpha wrote:It's not that a new ball acts differently, it's that it's more difficult to get it to act so as to get reverse, if you see what I mean. The margins are much smaller because the boundary layer on the leg side separates earlier than with an old ball. But it's still theoretically possible.


But what governs the rate of separation? As far as I understand, the rough ball has a surface which facilitates and allows it more, but if the ball is the same shape/weight all the time, why would an unaffected ball swing early? Or maybe its small indentations after the first ball that can effect it ?
2010 French Open fantasy league guru 2010 Wimbledon fantasy league guru 2014 Masters golf fantasy guru 2015 Players Championship FL Guru 2016 Masters Golf Fantasy Guru

And a hat and bra to you too, my good sirs!
sussexpob
 
Posts: 35322
Joined: Sun Jan 24, 2010 5:14 pm
Location: Asker, Norway
Team(s) Supported: Sussex and England Cricket, Vålerenga Fotball/FC Barcelona/Seagulls! ....
England and Norway at everything else

Re: Ball tampering, should the rules be relaxed?

Postby sussexpob » Fri Jun 14, 2013 3:36 pm

Sorry DA...physics nave came easy, I dont really understand
2010 French Open fantasy league guru 2010 Wimbledon fantasy league guru 2014 Masters golf fantasy guru 2015 Players Championship FL Guru 2016 Masters Golf Fantasy Guru

And a hat and bra to you too, my good sirs!
sussexpob
 
Posts: 35322
Joined: Sun Jan 24, 2010 5:14 pm
Location: Asker, Norway
Team(s) Supported: Sussex and England Cricket, Vålerenga Fotball/FC Barcelona/Seagulls! ....
England and Norway at everything else

Re: Ball tampering, should the rules be relaxed?

Postby DeltaAlpha » Fri Jun 14, 2013 3:42 pm

Basically, the separation is determined by the smoothness of the surface and, contrary to what might be expected, the air flows faster over, and separates later from, a rough surface than a smooth one... provided it's not too rough. Think of the pits on golf balls - without them, a drive would go less than half the distance.

I found the thread on the subject, but the main diagram has gone AWOL - I'll see if I can find it somewhere.

viewtopic.php?f=10&t=2311
2011-12 CMS winter chess champion
2011 CMS spring chess champion
DeltaAlpha
 
Posts: 6277
Joined: Sat Dec 05, 2009 3:49 pm
Location: Lancashire
Team(s) Supported: England

Re: Ball tampering, should the rules be relaxed?

Postby sussexpob » Fri Jun 14, 2013 3:50 pm

DeltaAlpha wrote:Basically, the separation is determined by the smoothness of the surface and, contrary to what might be expected, the air flows faster over, and separates later from, a rough surface than a smooth one... provided it's not too rough. Think of the pits on golf balls - without them, a drive would go less than half the distance.

I found the thread on the subject, but the main diagram has gone AWOL - I'll see if I can find it somewhere.

viewtopic.php?f=10&t=2311


Next question then...

Why do dimples increase the speed a ball moves through air? Seems a strange logic

:aww
2010 French Open fantasy league guru 2010 Wimbledon fantasy league guru 2014 Masters golf fantasy guru 2015 Players Championship FL Guru 2016 Masters Golf Fantasy Guru

And a hat and bra to you too, my good sirs!
sussexpob
 
Posts: 35322
Joined: Sun Jan 24, 2010 5:14 pm
Location: Asker, Norway
Team(s) Supported: Sussex and England Cricket, Vålerenga Fotball/FC Barcelona/Seagulls! ....
England and Norway at everything else

Re: Ball tampering, should the rules be relaxed?

Postby DeltaAlpha » Fri Jun 14, 2013 4:00 pm

It doesn't increase the speed of the ball, it makes it take longer to slow down. This is because the dimples make the air-flow 'turbulent' - i.e. the air is moving randomly in all directions. This in turn makes the boundary layers separate later and, at the back of the ball, the area of low pressure - the wake - has a smaller area and therefore has less effect. With smooth surfaces, the boundary layers separate earlier, the wake has a greater area and so has a greater effect.

You can see this quite clearly with a balloon - knock it horizontally though the air and it will move quickly at first and then suddenly slow down and fall to the floor. This is because the boundary layers are initially turbulent - due to the speed of the balloon - and then become 'laminar' - i.e. flowing tangentially to the ball. The turbulent layers separate later than the laminar ones, so the wake has less slowing-down effect.
2011-12 CMS winter chess champion
2011 CMS spring chess champion
DeltaAlpha
 
Posts: 6277
Joined: Sat Dec 05, 2009 3:49 pm
Location: Lancashire
Team(s) Supported: England

Re: Ball tampering, should the rules be relaxed?

Postby sussexpob » Fri Jun 14, 2013 4:06 pm

DeltaAlpha wrote:It's because the dimples make the air-flow 'turbulent' - i.e. the air is moving randomly in all directions. This makes the boundary layers separate later and, at the back of the ball, the area of low pressure - the wake - has a smaller area and therefore has less effect. With smooth surfaces, the boundary layers separate earlier, and the wake has a greater effect.

You can see this quite clearly with a balloon - knock it horizontally though the air and it will move quickly at first and then suddenly slow down and fall to the floor. This is because the boundary layers are initially turbulent - due to the speed of the balloon - and then become 'laminar' - i.e. flowing tangentially to the ball. The turbulent layers separate later than the laminar ones, so the wake has less slowing-down effect.


I would expect an area of low pressure airflow behind the ball would create less air resistance to the ball moving forward, so the opposite will be true? Obviously I am not questioning your word, merely my understanding, but it is confusingly opposite to what you expect.

I mean for instance, you expect dimples to create a bigger surface area, which would in turn impact the speed or distance negatively?
2010 French Open fantasy league guru 2010 Wimbledon fantasy league guru 2014 Masters golf fantasy guru 2015 Players Championship FL Guru 2016 Masters Golf Fantasy Guru

And a hat and bra to you too, my good sirs!
sussexpob
 
Posts: 35322
Joined: Sun Jan 24, 2010 5:14 pm
Location: Asker, Norway
Team(s) Supported: Sussex and England Cricket, Vålerenga Fotball/FC Barcelona/Seagulls! ....
England and Norway at everything else

Re: Ball tampering, should the rules be relaxed?

Postby DeltaAlpha » Fri Jun 14, 2013 4:16 pm

It is confusing and counter-intuitive, sussex, but the thing is that, at the speeds we're concerned with, the air in contact with the ball isn't actually moving relative to the ball, so air resistance doesn't come into it. It's the wake that causes the ball to slow down, and the smaller that is, the more slowly the ball will slow down.

The other thing that's counter-intuitive is that the air actually flows more easily over a rough (or dimpled) surface than over a smooth one because the roughness causes turbulence in the boundary layer. Provided the surface isn't too rough, that is!

Better get back on-topic! I've found the diagram and will tack it on to the thread that I mentioned earlier.
2011-12 CMS winter chess champion
2011 CMS spring chess champion
DeltaAlpha
 
Posts: 6277
Joined: Sat Dec 05, 2009 3:49 pm
Location: Lancashire
Team(s) Supported: England

Re: Ball tampering, should the rules be relaxed?

Postby mikesiva » Sat Jun 15, 2013 2:28 pm

SaintPowelly wrote:
hopeforthebest wrote:
SaintPowelly wrote:Bailey didn't actually accused England of tampering.

He was asked a direct question about if he was surprised how quickly they got it to reverse swing.


The Aussie chairman of selectors came out and didn't agree with Bailey's remarks so he thought so.


Bailey said he was unsure how they got swing, and Australia didnt and the other game played at the same venue got no swing.

He never said he thought England cheated.

Bob Willis pulled no punches when he was on Sky....practically accused England of ball-tampering.

DA, I will move the thread in question out of File Thirteen and into International Cricket.
:thumb
Nobody has a stance quite like the mighty Shivnarine....

Australia-New Zealand ODI's Prediction Guru
2009 spring chess league guru
Pakistan vs Australia ODI's Prediction Guru
World 20/20 Prediction Guru
2010-2011 final places Premiership footy prediction guru
2011 French Open tennis prediction guru
2011 Bang vs WI combined fantasy guru
2012 Caribbean T20 fantasy guru
2012 Euros prediction guru
2012-2013 final places Premiership footy prediction guru
2013 Champions League prediction guru
2013 chess mini-tournament guru
2014 Eng-SL combined fantasy guru
2014 chess mini-tournament guru
2017 Australian Open tennis guru
User avatar
mikesiva
 
Posts: 38752
Joined: Sun Sep 21, 2008 7:41 pm
Location: Hertfordshire, England
Team(s) Supported: First - West Indies
Joint Second - England, Sri Lanka

Re: Ball tampering, should the rules be relaxed?

Postby hopeforthebest » Sat Jun 15, 2013 2:31 pm

Apparently Bob Willis has accused England of ball tampering, it seems he claims Cook's reaction when the umpires changed the ball proves it. The current news is that the umpires changed the ball because it was out of shape.
Work expands to fill the time available, so why do today what can be put off until tomorrow.


2017 West Indies v Pakistan ODI FL Guru
2016 Bangladesh v England Combined FL Guru
2016 India v New Zealand ODI FL Guru
2015 India v South Africa ODI FL guru.
2013 Ashes fantasy prediction guru
2013 NZ in England combined FL guru.
hopeforthebest
 
Posts: 15058
Joined: Thu Jun 02, 2011 12:50 pm
Location: The Netherlands
Team(s) Supported: Warwickshire and England

Re: Ball tampering, should the rules be relaxed?

Postby yuppie » Sat Jun 15, 2013 9:11 pm

Any ideas of who the player is who Willis claims is scratching the ball?

Would be interesting to hear what Alam Daar says as the reason why he changed the ball? England did not want it changed, the batsman said nothing, so why did the umpire change it? Specially as it was starting to reverse......
2009 New Zealand Vs India Tests Prediction Guru
Prem final standings prediction guru
2010 AFL Footy Tipping Champion
User avatar
yuppie
 
Posts: 15613
Joined: Sun Sep 21, 2008 8:07 pm
Location: Lund, Sweden
Team(s) Supported: Australia, Nottingham Forest, Carlton.

PreviousNext

Return to International Cricket

Who is online

Users browsing this forum: No registered users and 29 guests