200 Best MCQs on fluid flow- biochemical engineering
Q33). The viscosity of the culture fluid is classified as both pseudoplastic and thixotropic which indicates that the viscosity
a).increases with stirring speed but decreases with mixing time
b).increases with stirring speed and increases with mixing time
c).decreases with stirring speed but increases with mixing time
d).decreases with stirring speed and decreases with mixing time
Correct Answer:
decreases with stirring speed and decreases with mixing time
Explaination:
Q34). Pluronic F68 is added to cell culture media as
a).a nutrient
b).a shear protectorant
c).to increase oxygen transfer rates
d).all of these
Correct Answer:
a shear protectorant
Explaination:
Q35). A stirred tank reactor containing a fluid with a density of 2.5 g.ml-1 and viscosity of 0.002 kg m-1.s-1 is mixed at 120 rpm. If the fluid is mixed with an impeller having diameter 50 cm, then the Reynolds number of the liquid in the reactor is
a).2500
b).100
c).12,50,000
d).1000000
Correct Answer:
12,50,000
Explaination:
Q36). If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is
a).newtonian
b).rheopectic
c).viscoelastic
d).thixotropic
Correct Answer:
thixotropic
Explaination:
Q37). Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology?
a).The Kolmogorov eddy size is a measure of the smallest eddy size in a liquid
b).When the Kolmogorov eddy size become equivalent or smaller than the cell or particle diameter, then the cell or particle will become susceptible to shear damage
c).At the Kolmogorov eddy size, much of the energy of the originating eddy will be released
d).All of the above
Correct Answer:
All of the above
Explaination:
Q38). A thixotropic fluid is one in which the viscosity
a).is constant regardless of the stirrer speed or mixing time
b).changes during mixing but returns to its original state after mixing
c).increases with mixing time
d).decreases with mixing time
Correct Answer:
decreases with mixing time
Explaination:
Q39). Newtonian fluid is one in which the viscosity
a).remains constant with time and power input
b).increases with the level of power input
c).decreases with the level of power input
d).drastically increases with the level of power input
Correct Answer:
remains constant with time and power input
Explaination:
Q40). Reynolds number for laminar flow over a plate should be less than
a).500 mm
b).5 x 10^-5
c).5 x 10^5
d).5 m
Correct Answer:
5 x 10^5
Explaination: