Key Terms
Definition
A living membrane expends energy to move substances across it, sometimes against the concentration gradient.
V/t Units
M^3/s (SI); also L/min in practice.
Entrainment
High-velocity fluid creates a low-pressure region that pulls another fluid into the stream. Examples include Bunsen burn
Wings and sails
Air moves faster over the curved upper surface of a wing than underneath. Lower pressure on top creates net upward lift.
Shower curtain effect
High-velocity water and air inside the shower create a low-pressure region; atmospheric pressure on the outside pushes t
Vehicle interaction
Fast-moving air between two vehicles (a car passing a truck) creates a low-pressure zone; both vehicles are pushed toget
Velocity measurement (pitot tube)
One tube faces oncoming flow (creating a dead spot, v = 0); the second tube has flow past it. The pressure difference gi
Derivation
Apply Bernoulli's equation from the surface (point 1) to the exit (point 2). Both pressures equal atmospheric and cancel
Laminar flow
Fluid moves in smooth parallel layers (streamlines) that do not mix. Velocity is highest at the center of a tube, zero a
Turbulent flow
Layers mix; eddies and swirls form. Requires more energy.
Formula
Eta = F*L / (A*v) Units: Pa*s (or N*s/m^2)
Flow rate through a tube
Q = (P1 - P2)*pi*r^4 / (8*eta*L)
Resistance of a tube
R = 8*eta*L / (pi*r^4)
Therefore
Q = delta-P / R (analogous to Ohm's law)
Korotkoff sounds
Turbulent sounds heard when measuring blood pressure with a cuff. The cuff partially collapses the brachial artery; as c