1. Ning Shen EAS 6410 Personal Project Apr 25, 2006
A Simple Reaction-Diffusion Model for Gas-Solid Interaction in the Atmosphere
Ning Shen
EAS 6410
Personal Project
Apr 25, 2006

2. Overview
Introduction
Models
Simulation
Conclusion

3. Introduction Gas-solid interaction Reaction-diffusion problems
Dimensionless UV penetration depth - H
Dimensionless reaction rate - K

4. Models 1-dimensional model Multi-dimensional models Boundary and
………
Infinitely large film
Boundary and
Initial conditions
Boundary and
Initial conditions
………
Infinitely long cylinder
Dimensionless

5. 1-Demension Simulation
Steady-State Solution
Time-Dependant Solution
dimensionless
Boundary and
Initial conditions

6. Steady-State Solution
Dependence of K ( H=0.1)
Dependence of H ( K=1 )

7. Time-Dependant Solution
H << 1 and K = 1

8. Time-Dependant Concentration Distribution
Steady State
t =
t =
Fig 5(d)

9. Different Circumstances
H << 1 and K = 10
0 < t < 2
H > 1 and K = 10
0 < t < 2
H > 1 and K = 1
0 < t < 2

10. 2-Dimension Simulation
H = 0.5, K = 1
H = 0.5, K = 100
H = 0.1, K = 1
H = 0.1, K = 100
Steady-State Distribution
H = 2, K = 1
H = 2, K = 100 UV
R = 0.5 x y
(0,0)
y-(R-sqrt(R2-x2))

11. Conclusion
The bigger the K is, the faster the Steady-State will be reached.
Dimensionless UV penetration depth H controls the asymmetry of the distribution
The same dependence of H and K was found in multi-D cases