While watching cricket match you might have seen bowlers rub the ball often against their trousers. Have you even wondered why bowlers do so? We will discuss the reason behind the rubbing of ball in this article.
Actually, whenever you rub the ball, no umpire or match referee tells you anything. At the same time, if you violate the ICC rules while rubbing it, then you also have to pay its loss. Let us first tell you why the bowler does this. Whenever the ball is new, it falls straight, very little swing (out swing, in swing or reverse swing) is found. In such a situation, only the batsman gets the benefit which no bowler wants.
Bowlers try to make the ball shine and smooth mainly for making it to slip on the bat and make it possible to render the batsman out by catches at slips and by the wicket keeper. The smooth ball is also likely to misbehave while it is hit for a bigger shot and are caught anywhere in the field an on boundaries.
Now,let us understand the science behind this.
When bowler is rubbing one side of ball he is actually polishing or smoothening the surface of the ball. Other half of the ball remains as it is or more rough. When bowler throws the ball at high velocity, low pressure is created near smooth surface and high pressure area is created on rougher side. This pressure differential SWINGS ball in air.
To look at this aerodynamically, one must understand the concept of boundary layer formation and separation. Boundary Layer is a layer of fluid (in this case, Air) which tends to stick to the surface of the object (The ball) when the object tries to move through the fluid. The boundary layer does not cause any effect on the object’s flow through the fluid (except for resistance) until it separates. Boundary layer separation occurs when the flow velocity increases to such an extent that the pressure difference increases drastically in the flow direction. Boundary Layer separation causes formation of eddies which then resist the movement of the flowing object. The Boundary Layer formed on any surface can be either Laminar or Turbulent.
To look at this aerodynamically, one must understand the concept of boundary layer formation and separation. Boundary Layer is a layer of fluid (in this case, Air) which tends to stick to the surface of the object (The ball) when the object tries to move through the fluid. The boundary layer does not cause any effect on the object’s flow through the fluid (except for resistance) until it separates. Boundary layer separation occurs when the flow velocity increases to such an extent that the pressure difference increases drastically in the flow direction. Boundary Layer separation causes formation of eddies which then resist the movement of the flowing object. The Boundary Layer formed on any surface can be either Laminar or Turbulent.
In Laminar Flow, the flow of the fluid is in organised parallel lines. Whereas, the Turbulent Boundary Layer the fluid particles move in disorganized and intersecting paths.Therefore, ball is made rough so that turbulent boundary layer is formed which results in disorganized movement of ball.
In conclusion, we have seen that science behind rubbing the ball.Thank you reading the article.
In conclusion, we have seen that science behind rubbing the ball.Thank you reading the article.
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