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  • Question
  • 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

  • Correct Answer
  • dilatant, rheopectic fluid 


  • Fluid Flow problems


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    • 1. 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
    • 2. 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
    • 3. 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
    • 4. 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
    • 5. 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
    • Discuss
    • 6. A rheopectic 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 mixing time
    • D. decreases with mixing time
    • Discuss
    • 7. The viscous nature of a non-Newtonian fluid

    • Options
    • 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
    • Discuss
    • 8. Reynolds number for laminar flow over a plate should be less than

    • Options
    • A. 500 mm
    • B. 5 x 10-5
    • C. 5 x 105
    • D. 5 m
    • Discuss
    • 9. Newtonian fluid is one in which the viscosity

    • Options
    • 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
    • Discuss
    • 10. A Brookfield viscometer cannot determine the shear stress because

    • Options
    • 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
    • Discuss


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