{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# lect23 - • flow is reversible • flow equations are...

This preview shows pages 1–2. Sign up to view the full content.

Biology 427 2007 Lecture 23. Life at Low Reynolds Numbers •Recap High Re Number Swimming •Low Reynolds Number Phenomena •Ciliary locomotion •Dilemmas about force generation •Regulation of cilia and flagella Thrust = C D ! S u 2 /2 + “something else” = C D ! S u 2 /2 + "! V du/dt “Drag” = C Dbody ! S body u body 2 /2 + " body ! V body du body /dt Balance of forces ( thrust and “ drag” )for a swimmer! Thrust = Drag a small reading from Vogel a demonstration A reading and some movies

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
m du/dt = -6 ! R μ u 3 μ m 0.03 mm/s E. coli: how far does this glide? Swimming at Low Reynolds numbers (<1) Phenomenological issues:
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: • flow is reversible • flow equations are linear • inertia is negligible • disturbances are manefest over huge relative distances. • boundaries are all important • shape matters considerably less A sphere: Low Re High Re C D = 24/Re 0.1 D = 6 ! r m U 0.1 0.5 r ! r 2 U 2 2 ! " U l ln(l/a) - 0.897 D = 4 ! " U l ln(l/a) + 0.193 D = Two important questions: • What are the cellular mechanisms that generate force? • What are the fluid dynamic mechanisms that propel the animal?...
View Full Document

{[ snackBarMessage ]}

### Page1 / 2

lect23 - • flow is reversible • flow equations are...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online