# The Reynolds number is found out for a flow in a circular pipe. This circular pipe is moulded into a square pipe, keeping length of the pipe same. Ignore the thickness of the pipe. The Reynolds number changes by __________

The Reynolds number is found out for a flow in a circular pipe. This circular pipe is moulded into a square pipe, keeping length of the pipe same. Ignore the thickness of the pipe. The Reynolds number changes by __________

(a) 57% decrease

(b) 57% increase

(c) 43% decrease

(d) 43% increase

The question was posed to me in examination.

This key question is from Flow of Viscous Fluid Through Circular Pipes in division Viscous Flow & Turbulent Flow of Fluid Mechanics

by (362k points)
selected

Right answer is (b) 57% increase

The explanation is: The Reynolds number directly depends upon the hydraulic diameter of the pipe. Suppose the diameter of the pipe is D, the hydraulic diameter of square pipe is 1.57D. Hence, 57% increase.

+1 vote
+1 vote
+1 vote
+1 vote
+1 vote
+1 vote
+1 vote
+1 vote