fluid mechanics Flashcards
what is fluid mechanics
the study of an object or human body that travels through liquid or gas
what is a dynamic fluid force
- concerned with the movements of liquids and gases
- drag and lift
- drag effects cycling, swimming, sprinting
- drag and lift effects discus, javelin
what is a drag force
- slows something down
- resistance
- caused by body traveling through fluid
- acts in opposition to the direction of motion
- drag has a negative effect on velocity
- combination of air resistance and friction
- performers try to minimise drag in order to increase performance
what are the 2 types of drag
surface= friction between the surface of an object and the fluid environment
- swimmers wear specialised smooth suits, caps and shave body hair to make them smooth and more streamlined= this increases velocity
form= relates to the impact of the fluid environment on an object
- forces affecting the leading edge of an object increases form drag
- forces affecting the trailing edge of an object reduces form drag
- relates to streamlining
- large form drag offers less terbulent air for anything following
- cyclists use another riders slipstream, form drag is reduced for the second cyclist
streamlining
shaping a body so it can move through fluid quickly and effectively
streamlined bodies incorporate a gradual taper
streamlined shape allows air to move past in layers
reduces fluid drag
turbulent flow
flow in which fluid undergoes irrecular fluctuations, or mixing, constantly undergoing changes in magnitude and direction
increases friction and fluid drag and decreases velocity
laminar flow
layers of fluid flow slide smoothly over one another
they undertake smooth paths or layers
less resistant to movement
how to reduce form drag in cycling
- as the wind hits the front cyclist, air goes around the sides
- the cyclist behind uses the air pocket created
- needs to be close, 15-30 cm
- can save 30% more energy
