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

Overview Introduction Models Simulation Conclusion

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

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

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

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

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

Time-Dependant Concentration Distribution Steady State t = 0.6- 2.0 t = 2.0- 8.0 Fig 5(d)

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

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))

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