Author Question: Applying the principles of Poiseuille's law, which statement is true? a. The resistance offered ... (Read 71 times)

leo leo · **on:** Jul 16, 2018

Applying the principles of Poiseuille's law, which statement is true?

a. The resistance offered by a tube is in-versely proportional to its length.
b. As the radius of a tube decreases, the pressure gradient increases.
c. The more viscous the fluid, the easier it is to move the fluid through a tube.
d. The driving pressure of a gas is indirectly proportional with the length of the tube.

Question 2

As a fluid flows through a tube of uniform diameter, pressure drops progressively over the length of the tube. This illustrates an application of which of the following?

a. Coanda effect c. Bernoulli principle
b. Venturi principle d. Reynolds' number

mcomstock09 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: B
Poiseuille's law can be rewritten as: P = Q (8nl)/(r4). According to this equation, the fol-lowing statements can be made. The more viscous a fluid, the greater the pressure gradient re-quired to cause it to move through a given tube. The resistance offered by a tube is directly pro-portional to its length. The pressure required to achieve a given flow through a tube must increase in direct proportion to the length of the tube. The resistance to flow is inversely proportional to the fourth power of the radius. Small changes in the radius of a tube will cause profound in-creases in the resistance to flow through that tube.

Answer to Question 2

ANS: D
Bernoulli stated that As the forward velocity of a gas, or liquid, moving through a tube increas-es, the lateral wall pressure of the tube will decrease. Venturi postulated that pressure drops of fluids moving through constriction along a tube can be reversed if there is gradual dilation in the tube distal to the constriction. The Coanda effect is also based on the Bernoulli principle and demonstrates that water or gas flow can be deflected through a full 180 by careful placement of postconstriction extensions. Reynolds' number is the result of this mathematical equation: NR = v d (2r/). The turbulent flow is greater when the Reynolds' number exceeds 2000.