
304 Industrial Air Quality and Ventilation
© 2010 Taylor & Francis Group, LLC
where M is dust release intensity (g/s); δ is a function equal to
δ δ
δ
yy zH zH
()
=≠ −
()
=≠
()
=
00 0
1
yaat atyz
H
Boundary conditions are based on the natural provision of diminishing concentra-
tion at an innite distance from the source
q → 0 at z → ∞; (5.194)
q → 0 at y → ∞ (5.195)
and on a low average turbulent ow of contaminant near the ground
z
=
at z = 0. (5.196)
For sources located at small elevations (H measuring a few meters), a power law
describes the wind speed and exchange factor
z
z
kk
z
z
z
=
=
1
1
(5.197)
where u
1
is the wi