Page 277 - Formulas and Calculations for Petroleum Engineering

270 Formulas and calculations for petroleum engineering

5.27 Diffusion from an instantaneous point source

Input(s)
m A : Mass of Species A (g)
2
D AB : Binary Diffusivity for System A-B (cm /s)
t: Time (s)
r: Radial Coordinate, L (m)

Output(s)
3
r A : Density of Species A (g/cm )

Formula(s)

0 1
2
m A r
r ¼ @ A exp
A 3 4 D t
ð 4 p D tÞ 2 AB
AB
Reference: Bird, R.B., Stewart, W.E. and Lightfoot, E.N. (2002). Transport Phenomena (Second ed.). John Wiley & Sons,
Chapter: 20, Page: 650.

5.28 Diffusion in a moving film

Input(s)

H: Initial Height of Gas Column (cm)
C: Concentration (g/cc)
t: Time (s)

Output(s)

h(t): Height of Gas Interface (cm)

Formula(s)

0:5 ! !
Ct

htðÞ ¼ H 1+ 1
H 2
Reference: Bird, R.B., Stewart, W.E. and Lightfoot, E.N. (2002). Transport Phenomena (Second Ed.). John Wiley & Sons,
Chapter: 18, Page: 549.

5.29 Diffusion in polymers

Input(s)
M: Molar Weight (g/mol)

Output(s)
2
D AB : Diffusivity (cm /s)