The University of Western Ontario
Faculty of Engineering
Department of Chemical and Biochemical Engineering
Air Pollution (CBE 4405 / CBE 9312)
Tutorial # 04
Problem – 1
A spherical particle with specific gravity 4 is settling in air, calculate the terminal settling
velocity for those cases: (assume density of air is 1.2 kg/m3 and the viscosity of air is 1.8x10-5
m2/s)
i) Diameter of particles = 1 µm. (0.01µ -100 µ) “acceptable range for stokes law”
ii) Diameter of particles =0.005 µm. (Assume λ = 0.07)
Solution:
i)
V=9 . 81∗10−12∗(4000−1 . 2)
18∗1. 8∗10−5=1. 21∗10−4m/sec
ii) D=0.005
μ
, very small.
