Fluid Flow Flashcards by Cathrina Chavez

The viscosity of liquid was classified as both
dilatant and rheopectic, which means that the
viscosity

a. increased with stirring speed but decreased
with mixing time

b. increased with stirring speed and increased
with mixing time

c. decreased with stirring speed but increased
with mixing time

d. decreased with stirring speed and decreased with mixing time

b. increased with stirring speed and increased
with mixing time

How well did you know this?

Not at all

Perfectly

A fluid in which the viscosity decreases with
increasing stirrer speed and mixing time, can be represented as

a. Newtonian fluid
b. pseudoplastic, thixotropic fluid
c. dilatant, rheopectic fluid
d. dilatant, pseudoplastic fluid

b. pseudoplastic, thixotropic fluid

How well did you know this?

Not at all

Perfectly

Filamentous fungal cells are more shear
sensitive than bacterial cells because of

a. the presence of citin in cell walls of
filamentous fungi

b. larger in size than bacterial cells and
therefore are more susceptible to shear
forces

c. fungal cells are much larger than bacterial
cells

d. all of the above

How well did you know this?

Not at all

Perfectly

The viscosity of water at STP is approximately

a. 0.005 kg.m-1.s-1
b. 0.001 kg.m-1.s-1
c. 0.003 kg.m-2.s-1
d. 0.1 g.cm-1.s-1

b. 0.001 kg.m-1.s-1

How well did you know this?

Not at all

Perfectly

Bubble free aeration systems requires

a. silicone tubing or gas permeable membranes to facilitate gas transfer

b. carbon dioxide instead of air to supply
oxygen

c. silicone tubing or gas permeable membranes to remove carbon dioxide by
oxygen in the form of hydrogen peroxide

d. filled headspace of the reactor with carbon
dioxide

a. silicone tubing or gas permeable membranes to facilitate gas transfer

How well did you know this?

Not at all

Perfectly

If the viscosity of a fluid decreases with
increasing stirrer speed, then the nature of the fluid is

a. Newtonian
b. Pseudoplastic
c. Dilatant
d. Thixotropic

b. Pseudoplastic

How well did you know this?

Not at all

Perfectly

A pseudoplastic 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 increasing stirrer speed

d. decreases with increasing stirrer speed

How well did you know this?

Not at all

Perfectly

A viscoelastic 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 increasing stirrer speed

d. decreases with increasing stirrer speed

b. changes during mixing but returns to its original state after mixing

How well did you know this?

Not at all

Perfectly

Mixing in stirred tank reactors can

a. be described as either laminar, transient or
turbulent

b. achieve turbulent conditions by increasing
the stirrer speed

c. induce laminar flow conditions by the
addition of baffles

d. all of the above

a. be described as either laminar, transient or turbulent

How well did you know this?

Not at all

Perfectly

In animal cell bioreactor, bubble damage can be minimized by

a. the addition of a shear protectorant
b. using a bubble free oxygen delivery system
c. headspace aeration
d. all of the above

d. all of the above

How well did you know this?

Not at all

Perfectly

The viscosity of a fluid changes with either
stirrer speed or mixing time. But when mixing
ceases, the viscosity returns to its original state. This fluid is best described as

a. Newtonian
b. Rheopectic
c. Viscoelastic
d. Thixotropic

c. Viscoelastic

How well did you know this?

Not at all

Perfectly

In sparged mammalian cell bioreactors, the cell damage is caused because of

a. shear stress arising during mixing of the
cell culture fluid

b. shear stresses arising from the breakup of
bubbles at the liquid surface

c. shear stresses between bubbles in foam at
the liquid surface

d. all of the above

a. shear stress arising during mixing of the cell culture fluid

How well did you know this?

Not at all

Perfectly

The SI unit for viscosity is
a. kg.m-1. s-1
b. kg.m-2. s-2
c. kg.m-3. s-1
d. kg.m-1.s-2

a. kg.m-1. s-1

How well did you know this?

Not at all

Perfectly

The viscous nature of a non-Newtonian fluid

a. remains constant with time and power input

b. changes with the level of power input
and/or the length of time during which the
fluid is mixed

c. is similar to that of a perfect gas

d. is similar to that of water

b. changes with the level of power input
and/or the length of time during which the
fluid is mixed

How well did you know this?

Not at all

Perfectly

Which of the following compound, if added to
a solution will lead to the greatest increase in
viscosity?

a. A globular protein
b. Glucose
c. A long chain protein such as albumin
d. Water

c. A long chain protein such as albumin

How well did you know this?

Not at all

Perfectly

A Brookfield viscometer measures viscosity by
determining

a. the shear stress
b. the shear rate
c. the shear stress and shear rate
d. the torque required to move an impeller at
a set speed

d. the torque required to move an impeller at a set speed

How well did you know this?

Not at all

Perfectly

Which of the following factors will affect the
sensitivity of animal cells to shear conditions?

a. Cell size
b. Availability of nutrients in the medium
c. The presence of shear protectorants in the
medium
d. All of the above

d. All of the above

How well did you know this?

Not at all

Perfectly

The best described action of Pluronic F68 (non
ionic detergent) in a cell culture medium is that, it

a. acts on the surface properties of the cells
and the culture medium
b. provides nutrients for the cells
c. acts as a flocculant
d. acts as a coagulant

a. acts on the surface properties of the cells and the culture medium

Water is a
a. Newtonian fluid
b. Pseudoplastic
c. Dilatant
d. Rheopectic

a. Newtonian fluid

Which of the following affect the Kolmogorov
eddy size?

a. Stirrer speed
b. Physical properties of the liquid
c. Size and type of impeller
d. All of these

d. All of these

A liquid is flowing at 11,400 l.h-1 along a
pipeline having a diameter of 4 cm. If the liquid has a density of 1 g.ml-1 and viscosity of
0.001kg.m-1.s-1, then the liquid would be in the

a. laminar phase
b. transient phase
c. turbulent phase
d. any of the phasec. turbulent phase

c. turbulent phase

The viscosity of a fluid increases with the
length of time that it is being mixed. This fluid
would be best described as being

a. Newtonian
b. Rheopectic
c. Viscoelastic
d. Thixotropic

b. Rheopectic

Which of the following can act as a shear
protectorant?

a. Serum
b. Silicone oil
c. Glucose
d. Glutamic acid

a. Serum

The viscosity of a fluid increases with
increasing stirrer speed. This fluid would be
best described as being

a. Newtonian
b. Pseudoplastic
c. Dilatant
d. Thixotropic

c. Dilatant

A dilatant 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 increasing stirrer speed d. decreases with increasing stirrer speed

c. increases with increasing stirrer speed

A rheopectic 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

c. increases with mixing time

A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as a. Newtonian fluid b. pseudoplastic, thixotropic fluid c. dilatant, rheopectic fluid d. dilatant pseudoplastic fluid

c. dilatant, rheopectic fluid

The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of a. single celled bacteria b. filamentous fungi that form pellets c. filamentous fungi that grow as long poorly branched chains d. yeast

c. filamentous fungi that grow as long poorly branched chains

A Newtonian 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 increasing stirrer speed d. decreases with increasing stirrer speed

a. is constant regardless of the stirrer speed or mixing time

Which pattern of mixing is preferred in stirred tank reactors during the culture of aerobic microorganisms? a. Laminar flow b. Transient flow c. turbulent flow d. all of these

c. turbulent flow

Animal cell cultures do not have much effect on shear forces because a. the cell size is generally smaller than the critical eddy size at which shear will have an effect b. cells are larger than the critical eddy size at which shear will have an effect c. animal cells have cell walls d. animal cells have cell membranes

a. the cell size is generally smaller than the critical eddy size at which shear will have an effect

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

d. decreases with stirring speed and decreases with mixing time

A stirred tank reactor containing a fluid with a density of 2.5 g.ml-1 and viscosity of 0.002 kg m-1s-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. 1,000,000

c. 12,50,000

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

d. Thixotropic

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

d. All of the above

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

d. decreases with mixing time

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

a. remains constant with time and power input

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

c. 5 x 10^5

The approach which is commonly used to determine the level of damage to animal cells in a culture medium is to monitor a. the concentration of lactate in the medium b. the level of lactate oxidase activity in the medium c. the level of lactate dehydrogenase activity d. the level of lactase activity in the medium

c. the level of lactate dehydrogenase activity

A Brookfield viscometer cannot determine the shear stress because a. the shear stress is not defined b. a computer is required c. the impeller type is given only by numbers d. all of the above

a. the shear stress is not defined

Which of the following is correct? a. The viscosity of liquids and gases decrease with increasing temperature b. The viscosity of liquids and gases increase with increasing temperature c. the viscosity of gases increases with increasing temperature, but decreases in liquids d. the viscosity of gases decreases with increasing temperature, but decreases in liquids.

c. the viscosity of gases increases with increasing temperature, but decreases in liquids

The Komologorov eddy size a. is constant at all stirrer speeds b. increases with stirrer speed c. decreases with stirrer speed d. becomes zero when the stirrer speed is very low

c. decreases with stirrer speed

Pluronic F68 protects mammalian cells from damage stems as it is a/an a. surface active agent which stabilizes foams b. surface active agent which destabilizes foams c. excellent source of vitamins d. coagulant

a. surface active agent which stabilizes foams

Reynolds number for turbulent flow over a plate should be more than a. 5 x 10^-5 b. 10^6 c. 5 x 10^5 d. 500

b. 10^6