1. Yamada Science & Art Corporation www.ysasoft.com NUMERICAL SIMULATIONS OF AEROSOL TRANSPORT Ted Yamada （ YSA Corporation ） Aerosol transportGas transport Objective: Develop an aerosol transport model based on a Lagrangian particle algorithm

2. Yamada Science & Art Corporation www.ysasoft.com Lagrangian Particle Transport Algorithm U pi is the turbulence velocity at a particle location x i ; U i and u i are the mean and turbulence velocities, respectively.

3. Yamada Science & Art Corporation www.ysasoft.com Equations of Motion nudgingurban/forest canopy nudging urban/forest canopy

4. Yamada Science & Art Corporation www.ysasoft.com Equation for potential temperature Long-wave radiation flux is from Sasamori (1968). indicates the mean value in the horizontal plane. A similar equation for the mixing ratio of water vapor.

5. Yamada Science & Art Corporation www.ysasoft.com Turbulence Kinetic Energy Mellor-Yamada second-moment turbulence-closure equations (Level 2.5) provide the following equation for turbulence kinetic energy: ① diffusion in x, y, and z directions ② mechanical production ③ buoyancy production ④ dissipation ⑤ canopy drag production 1000 m 200 m daytime nighttime ③ ④ ② ① ② ④ ③

6. Yamada Science & Art Corporation www.ysasoft.com Turbulence Length Scale Equation for the length scale l is Terms on the right hand side of equation correspond to the counterparts of the turbulence energy equation 1000 m Blackadar (1962) 0 m

7. Yamada Science & Art Corporation www.ysasoft.com Concentration (Kernel Method) Assume concentration distributions around particles Obtain concentration at Y by summing contributions from all particles

8. Yamada Science & Art Corporation www.ysasoft.com Concentration Distributions （ Kernel Method ） Normal distribution was assumed for the Kernel Band width of Kernel was determined by using Taylor’s theory (1921) and sigma u, v, and w from the closure model

9. Yamada Science & Art Corporation www.ysasoft.com Buoyant and Dense Gas Van Dop (Atmos. Environ., 26A, 196-211, 1992) where ; 2 dz d T g N a   B>0 Buoyant plume; B=0 Neutral plume; B<0 Dense gas

10. Yamada Science & Art Corporation www.ysasoft.com Aerosol Transport whereIs an aerosol deposition velocity and For example, Is a critical value of vertical wind speed for suspension.

11. Yamada Science & Art Corporation www.ysasoft.com A2C (Atmosphere-to-CFD) Model System  A2Cflow (HOTMAC) – Mesoscale/CFD  Second-moment turbulence-closure ： (Mellor and Yamada Level 2.5, 1982)  Non-hydrostatic pressure ： HSMAC (Hirt and Cox, 1972)  A2Ct & d (RAPTAD) – Transport/Diffusion  Lagrangian particles and Kernel for concentration distributions  Winds and turbulence from A2Cflow

12. Yamada Science & Art Corporation www.ysasoft.com Gas and Aerosol Transport Computational domain: 250 km x 250 km x 1500 m (flat) Grid spacing: 5 km in horizontal, variable in vertical Date and simulation duration: Summer and 48 hours Animation period: 24 hours from Day 201, 0400 lst

13. Yamada Science & Art Corporation www.ysasoft.com Aerosol and Gas Transport ( vertical scale exaggerated 50 times ) Aerosol transportGas transport

14. Yamada Science & Art Corporation www.ysasoft.com Issues and Future Studies 1. Lagrangian time scale 2. Deposition and suspension velocities 3. Size distribution of aerosols

15. Yamada Science & Art Corporation www.ysasoft.com Thank you very much!