Questions
1.What is a laminar flow?
Laminar flow refers to a type of fluid motion characterized by smooth, orderly layers of fluid that move parallel
to each other with minimal mixing between the layers. In laminar flow, the fluid particles follow well-defined
paths or streamlines. This type of flow typically occurs at low velocities and low Reynolds numbers, usually
less than 2000 in circular pipes.
2. What is a turbulent flow?
Turbulent flow is a fluid flow regime characterized by chaotic and irregular fluid motion, involving significant
mixing of fluid layers and velocity fluctuations in both magnitude and direction. This flow occurs at high
velocities and higher Reynolds numbers, typically greater than 4000 in circular pipes. It is associated with
eddies and vortices, leading to increased energy loss due to friction.
3. Define kinematic viscosity. What is the unit of kinematic viscosity?
Kinematic viscosity is defined as the ratio of dynamic viscosity to fluid density. It represents the fluid's
resistance to flow under the influence of gravity and is a measure of its internal resistance to motion.
Mathematically, it is expressed as:
ν
=
ρ
μ
where
ν
is the kinematic viscosity, μ is the dynamic viscosity, and ρ is the fluid density.
The SI unit of kinematic viscosity is square meter per second (m²/s).
4. What is critical Reynolds number?
The critical Reynolds number is the threshold value of the Reynolds number at which fluid flow transitions
from laminar to turbulent. In the context of flow in a circular pipe, the critical Reynolds number is typically
around 2000. When the Reynolds number is below this value, flow remains laminar, while values above it
indicates the onset of turbulence. The transition region usually lies between Reynolds numbers of
approximately 2000 and 4000, depending on the system conditions.
Table
SL No. Flow Rate (m3/s) Velocity of
Flow (m/s)
Reynolds
Number
Visualized
Regime
1 0.000004713 0.0870 870 Laminar
2 0.0000196375 0.3624 3624 Transitional
