Question

The device used to demonstrate laminar and turbulent flow in pipes is:

• A. Pitot tube
• B. Venturimeter
• C. Reynolds apparatus
• D. Orifice meter

Hint:

The transition of flow is named after Osborne Reynolds.
Therefore, the corresponding demonstration setup is named the Reynolds apparatus.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to identify the experimental apparatus designed to demonstrate the transition between laminar and turbulent flow regimes in pipe flow.

Step 2: Key Formula or Approach: This is a theoretical question. The transition of flow is governed by the dimensionless Reynolds number:
\[ \text{Re} = \frac{\rho V D}{\mu} \] where \(\rho\) is fluid density, \(V\) is velocity, \(D\) is pipe diameter, and \(\mu\) is dynamic viscosity.

Step 3: Detailed Explanation:

• The Reynolds apparatus was historically designed by Osborne Reynolds to visually demonstrate laminar, transition, and turbulent flow.

• The apparatus consists of a glass tube connected to a water reservoir, with a fine needle to inject a colored dye filament along the central axis of the water stream.

• At low velocities (low \(\text{Re}\)), the dye remains as a straight, stable filament, indicating laminar flow.

• As velocity increases, the filament begins to oscillate (transition flow) and eventually disperses completely throughout the tube cross-section (turbulent flow).

• A Pitot tube is used for measuring localized velocity.

• A Venturimeter and an Orifice meter are flow-metering devices used to calculate volume flow rates.

Step 4: Final Answer:
The device used to demonstrate laminar and turbulent flow in pipes is the Reynolds apparatus.