Fluid

• Fluid Mechanics

  the natural science of fluids in motion
• Turbulent Flow 


  flow in which the velocity at any point varies erratically
• Laminar Flow


  a type of fluid flow in which fluid moves smoothly in individual layers or streams
• Boundary layer Separation


  where the boundary layer breaks away from the ball
• Factors affecting boundary layer separation point

  • velocity
  • surface roughness
  • shape
• balls with an oval shape cause minor drag because the separation occurs towards the rear
• balls with a round shape cause an increase in drag because the operation occurs further forwards
• low velocity = minor drag
• high velocity = increase drag
• Fluid resistance

  an object moves through a fluid and disturbs it
• two factors affecting fluid resistance

  • Density (air)
  • Viscosity (fluid)
• Types Of Drags

  • surface drag
  • pressure drag
  • wave drag
• Factors Affecting Surface Drag

  1. relative velocity of moving object
  2. relative roughness of surface object
  3. viscosity of fluid
  4. the surface area of the object
• Pressure Drag

  resistance created by the pressure differential between the front and back of an object moving through fluid
• Factors affecting pressure drag

  1. the cross section area of the object presented to the fluid
  2. velocity of the object
  3. surface roughness
  4. shape of the object
• Wave Drag


  the creation of waves forming resistance at the point where air and water interact
• factors affecting wave drag

  1. relative velocity of the wave
  2. technique
  3. open water or closed water
• Buoyancy


  refers to the upward force that keeps things afloat
• Archimedes Principle 


  states that the buoyant force acting on an object is equal to the weight of the fluid displaced by the object
• Positive Buoyancy


  displaces a volume of fluid equal to or greater than its weight and will float
• Negative Buoyancy


  displaces a volume of fluid less than its own weight and sinks
• Neutral Buoyancy


  when an object will neither sink or float but remains suspended in the fluid
• Lift


  refers to the component of force that acts perpendicular to the direction of flow
• Bernoulli's Principle


  relates to the pressure created from a moving fluid over an object whereby fast flowing fluid produces a low pressure area and slow moving fluid produces a high pressure area
• Magnus effect


  the term used to describe the effects of rotation on an object's path as it moves through a fluid
• Magnus Force


  the force causing an additional movement which changes the flight path of a rotating object
• Types Of Spin

  • topspin
  • backspin
  • sidespin
• Top spin


  causes the ball to drop and travel shorter in flight which allows for a greater margin when hitting over a net
• Backspin


  causes the ball to rise higher in the air and travel further
• Sidespin


  causes the ball to curve to the left or right depending on what side of the ball spin is imparted