Question

For which of the following Reynold's number, a flow is streamlined?

• A. 900
• B. 2100
• C. 2900
• D. 4000

Hint:

Reynolds Number $R_e = \frac{\rho v d}{\eta}$. Remember the critical limits: 2000 for Laminar and 3000 for Turbulent.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The Reynolds number ($R_e$) characterizes the nature of fluid flow:

• If $R_e<2000$, the flow is streamlined or laminar.
• If $2000<R_e<3000$, the flow is unstable or transitional.
• If $R_e>3000$, the flow is turbulent.

Step 2: Check Options:
We need to identify the value corresponding to streamlined flow ($R_e<2000$).

• 900 is less than 2000.
• 2100 is in the transition region.
• 2900 is in the transition region.
• 4000 is turbulent.

Thus, 900 is the correct value for streamlined flow.