Q1: Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is

ANS:B - <10

Laminar flow in the context of agitation of a liquid in an agitator occurs when the Reynolds number (ReReRe) is less than 10.

Explanation:

• Reynolds Number (ReReRe): This dimensionless number is used to predict flow patterns in different fluid flow situations. It is defined as: Re=ρ⋅v⋅DμRe = \frac{\rho \cdot v \cdot D}{\mu}Re=μρ⋅v⋅D​ Where:
  • ρ\rhoρ is the density of the fluid,
  • vvv is the velocity of the fluid relative to the object,
  • DDD is a characteristic linear dimension (diameter for a pipe or agitator),
  • μ\muμ is the dynamic viscosity of the fluid.
• Laminar Flow: Laminar flow is characterized by smooth, orderly fluid motion in parallel layers, with little or no mixing between layers. This occurs at low Reynolds numbers.
• Transition to Turbulent Flow: Turbulent flow typically begins to develop at Reynolds numbers greater than 2000 for flow in a straight pipe. For flow in an agitator, the transition from laminar to turbulent flow can vary but generally occurs around Reynolds numbers greater than 10.
• Specific to Agitation in Agitators: In the context of agitation in an agitator:
  • Laminar flow is observed when the Reynolds number is below 10.
  • Turbulent flow starts to develop as the Reynolds number exceeds this threshold, typically around 10 to 100 depending on the specific design and conditions of the agitator.