NESC9739 2DFLOW.
2DFLOW, 2-D Drainage Winds and Diffusion Simulation
NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROGRAM OR FUNCTION, METHOD OF SOLUTION, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, UNUSUAL FEATURES OF THE PROGRAM, RELATED AND AUXILIARY PROGRAMS, STATUS, REFERENCES, MACHINE REQUIREMENTS, LANGUAGE, OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED, OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHORS, MATERIAL, CATEGORIES
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| Program name | Package id | Status | Status date |
|---|---|---|---|
| 2DFLOW | NESC9739/01 | Tested | 13-FEB-1987 |
Machines used:
| Package ID | Orig. computer | Test computer |
|---|---|---|
| NESC9739/01 | DEC VAX 11/780 | DEC VAX 11/780 |
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3. DESCRIPTION OF PROGRAM OR FUNCTION
2DFLOW is a vertically integrated dynamical drainage flow model developed from conservation equations for momentum and mass in a terrain following coordinate system. Wind fields from the dynamical model drive a Monte Carlo transport and diffusion model. The model needs only topographic data, an Eulerian or Lagrangian time scale, and a surface drag coefficient for input data; it can be started with a motionless atmosphere.
2DFLOW is a vertically integrated dynamical drainage flow model developed from conservation equations for momentum and mass in a terrain following coordinate system. Wind fields from the dynamical model drive a Monte Carlo transport and diffusion model. The model needs only topographic data, an Eulerian or Lagrangian time scale, and a surface drag coefficient for input data; it can be started with a motionless atmosphere.
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NESC9739/01
NEA-DB executed the test case included in this package on a VAX-11/780 computer in 8 minutes, 17 seconds of CPU time.[ top ]
7. UNUSUAL FEATURES OF THE PROGRAM
2DFLOW has the following features which make it attractive as a practical tool for estimating the concentrations of pollutants released into nocturnal drainage winds: 1) No wind or temperature data are needed. A surface drag coefficient and Eulerian or Lagrangian time scale are required, but the model is not sensitive to their exact value. High resolution topographic data are required. 2) The model has been successfully tested at sites with rugged mountainous terrain and at a site with gently rolling terrain. 3) The model is two-dimensional (vertically integrated) so its computational requirements are moderate. 4) Maximum pollutant concentrations are predicted to within factors of 2 to 10 at specific points, based on observed and simulated concentration time series.
2DFLOW has the following features which make it attractive as a practical tool for estimating the concentrations of pollutants released into nocturnal drainage winds: 1) No wind or temperature data are needed. A surface drag coefficient and Eulerian or Lagrangian time scale are required, but the model is not sensitive to their exact value. High resolution topographic data are required. 2) The model has been successfully tested at sites with rugged mountainous terrain and at a site with gently rolling terrain. 3) The model is two-dimensional (vertically integrated) so its computational requirements are moderate. 4) Maximum pollutant concentrations are predicted to within factors of 2 to 10 at specific points, based on observed and simulated concentration time series.
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NESC9739/01, included references:
- A.J. Garrett and F.G. Smith:Two-Dimensional Simulations of Drainage Winds and Diffusion
Compared to Observations.
Reprinted from "Journal of Climate and Applied Meteorology",
Vol. 23, No. 4, pp. 597-610 (April 1984)
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NESC9739/01
| File name | File description | Records |
|---|---|---|
| NESC9739_01.001 | Information file | 79 |
| NESC9739_01.002 | 2DFLOW Source Program | 776 |
| NESC9739_01.003 | 2DFLOW test case input data | 20 |
| NESC9739_01.004 | 2DFLOW topographical data library | 59 |
| NESC9739_01.005 | 2DFLOW sample output (concentrations data) | 159 |
| NESC9739_01.006 | 2DFLOW sample output (winds data) | 289 |
Keywords: Monte Carlo method, air pollution, diffusion, flow models, surface air, topography, turbulence, weather.