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1
Model Strategies

• Simplify the equations
• Find an analytical solution

• Keep the equations
• Simplify the resolution

2
Gaussian Model

• Non reactive Pollutant
• Punctual Pollutant Source

• Constant Wind
• Homogenous Turbulence

3
Gaussian Model







4
Gaussian Model
Pasquill classes for atmospheric stability
5
Gaussian Model
with x the distance to the pollutant source km
6
Gaussian Model
with x the distance to the pollutant source km
7
Lagrangian Particles Model
Concentration
Additional turbulent wind speed
Air parcel trajectories
Concentration
8
Box Model
9
Lagrangian Column Model
Moving column
Wind flow Column trajectory
10
Eulerian 3D Model
Eulerian 3D mesh
11
Eulerian 3D Model
12
Eulerian 3D Model
Time
B.C.
B.C.
Dt
Boundary Conditions
i
i-1
i1
B.C.
Dx
Distance
Initial Conditions
13
Eulerian 3D Model
Exact solution after 5s
Initial condition
Exact solution
14
Eulerian 3D Model
with
15
Eulerian 3D Model
and
1st order
Initial condition
Initial condition
Dt0.5s
Solution after 5s
Dt0.1s
16
Eulerian 3D Model
17
Eulerian 3D Model
Initial condition
1st order
3d order