Swimming Mechanics: Reynolds Number Flashcards
What does inertia do?
- allows for continued fwd motion between swimming strokes
What needs to happen for the fish to move fwd?
- inertial forces (momentum) must be greater than viscous forces (drag)
What does Reynolds number do?
- predicts ratio of inertial vs. viscous forces
Fast swimmers have a ______ Re
high
Velocity ____ at small size
dominates
Bigger animals move ____. This is due to ____.
- faster
- inertial force
What is reynolds equation?
Re = body length * Speed * density of water / Viscosity of water
The ratio of reynolds number is what unit?
unitless because they cross eachother out
What is reynolds number used for?
to predict relative ease of locomotion in a fluid medium
What is constant in reynolds equation?
- density and viscosity
What do you look for in reynolds number?
- Re of body length (size) and speed
Re is proportional to what?
- inertial forces
What is Re inversely proportional to?
- viscous forces (DRAG)
What happens if Re>1?
- fish moves forward
Small fish have ____ drag. What does this mean?
- higher drag = slower moving
Define body/caudal fin propulsion
- rhythmic undulations of all or part of body
What is the result of sequential contraction of myomeres? What does it generate?
- propulsive wave moving down body
- generates force against water (incompressible)
Swimming involves ____ flexing of body from _____ to ______.
- lateral
- anterior to posterior
_____ increases until shed at caudal fin
- amplitude
What is power/thrust proportional to?
- rate of contraction
- amplitude of undulations (caudal fin)
- muscle mass
more muscle = ?
- more power generated
