L26/7/8 - Fluid Dynamics

• The relative velocity of a body wth respect to a fluid & the density, specific weight, & viscosity of the fluid affect the magnitudes of fluid forces
• The fluid force that enables flotation is buoyancy
• Drag is a fluid force that acts in the direction of the free stream fluid flow
• Surface/Skin Drag:

  • Skin friction is a component of drag that is derived from the sliding contacts bw/ successive layers of fluid close to the surface of a moving body
• Form Drag:

  • Caused by a pressure differential bw/ the lead & trailing/rear edges of a body moving with respect to a fluid
• Wave Drag:

  • Created by the formation of waves at the interface bw/ 2 different fluids, such as water & air
  • Lift force that can be generated perpendicular to the free stream fluid flow by a foil shaped object
• Lift:

  • Created by a pressure differential in the fluid on opposite sides of a body that results from differences in the velocity of the fluid flow
  • The lift generated by spin is known as the Magnus force
• The Magnus force is utilised in ball sports to bend the trajectory of the ball