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Home Biochemical Engineering Fluid Flow Comments

  • Question
  • Mixing in stirred tank reactors can


  • Options
  • 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

  • Correct Answer
  • be described as either laminar, transient or turbulent 


  • Fluid Flow problems


    Search Results


    • 1. Pluronic F68 protects mammalian cells from damage stems as it is a/an

    • Options
    • A. surface active agent which stabilizes foams
    • B. surface active agent which destabilizes foams
    • C. excellent source of vitamins
    • D. coagulant
    • Discuss
    • 2. Which of the following is correct?

    • Options
    • 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.
    • Discuss
    • 3. A viscoelastic fluid is one in which the viscosity

    • Options
    • 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
    • Discuss
    • 4. If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is

    • Options
    • A. newtonian
    • B. rheopectic
    • C. viscoelastic
    • D. thixotropic
    • Discuss
    • 5. Bubble free aeration systems requires

    • Options
    • 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
    • Discuss
    • 6. If the viscosity of a fluid decreases with increasing stirrer speed, then the nature of the fluid is

    • Options
    • A. newtonian
    • B. pseudoplastic
    • C. dilatant
    • D. thixotropic
    • Discuss
    • 7. Pluronic F68 is added to cell culture media as

    • Options
    • A. a nutrient
    • B. a shear protectorant
    • C. to increase oxygen transfer rates
    • D. all of these
    • Discuss
    • 8. Which of the following affect the Kolmogorov eddy size?

    • Options
    • A. Stirrer speed
    • B. Physical properties of the liquid
    • C. Size and type of impeller
    • D. All of these
    • Discuss
    • 9. The best described action of Pluronic F68 (non-ionic detergent) in a cell culture medium is that, it

    • Options
    • 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
    • Discuss
    • 10. A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as

    • Options
    • A. newtonian fluid
    • B. pseudoplastic, thixotropic fluid
    • C. dilatant, rheopectic fluid
    • D. dilatant pseudoplastic fluid
    • Discuss


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