Question

The Reynolds number is a dimensionless group defined for a fluid flowing in a pipe as Re Durho/μ whereD is pipe diameter, u is fluid velocity, rho is fluid density, and μ is fluid viscosity.When the value of the Reynolds number is less than about 2100, the flow is laminar—that is, the fluid flows in smooth streamlines. For Reynolds numbers above 2100, the flow is turbulent, characterized by a great deal of agitation. Liquid methyl ethyl ketone (MEK) flows through a pipe with an inner diameter of 2.067 inches at an average velocity of 0.48 ft/s. At the fluid temperature of 20°C the density of liquid MEK is 0.805 g/cm3 and the viscosity is 0.43 centipoise [1 cP 1:00 103 kg/ m s]. Without using a calculator, determine whether the flow is laminar or turbulent. Show your calculations.

Answer 1

the flow is turbulent

Step-by-step explanation:

The Reynolds number is given by

Re=ρVD/μ

where

V=fluid speed=0.48ft/s=0.146m/s

D=diameter=2.067in=0.0525m

ρ=density=0.805g/cm^3=805Kg/m^3

μ=0.43Cp=4.3x10^-4Pas

Re=(805)(0.146)(0.0525)/4.3x10^-4=14349.59

Re>2100 the flow is turbulent

Note: if you do not want to use a calculator you can use the graphs to calculate the Reynolds number according to their properties