Poiseuille’s equation does not hold if the flow velocity is high enough that turbulence sets in. The onset of turbulence occurs when the Reynolds number, Re, exceeds approximately 2000. Re is defined as
where is the average speed of the fluid, ρ is its density, η is its viscosity, and r is the radius of the tube in which the fluid is flowing. (a) Determine if blood flow through the aorta is laminar or turbulent when the average speed of blood in the aorta (r = 1.2 cm) during the resting part of the heart’s cycle is about 40cm/s. (b) During exercise, the blood-flow speed approximately doubles. Calculate the Reynolds number in this case, and determine if the flow is laminar or turbulent.
Dudaie 1 Physics II Chapter 21 Chapter 21 Electric Current & DirectCurrent Circuits 1. Electric Current a. The flow of electric charge from one place to another is known as electric current i. I=∆Q/∆ t 1. 1 A= 1C/s} ampere or amp b. Often charge is carried by electrons...