last modified: 13-FEB-1987 | catalog | categories | new | search |

NESC9739 2DFLOW.

2DFLOW, 2-D Drainage Winds and Diffusion Simulation

top ]
1. NAME OR DESIGNATION OF PROGRAM

2DFLOW.

top ]
2. COMPUTERS
To submit a request, click below on the link of the version you wish to order. Only liaison officers are authorised to submit online requests. Rules for requesters are available here.
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
top ]
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.

top ]
4. METHODS

The system of dynamical equations is solved numerically with a second-order finite difference scheme. Advection  of mass and momentum is calculated by the second upwind differencing or "donor cell" method.

top ]
6. TYPICAL RUNNING TIME
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.

top ]
9. STATUS
Package ID Status date Status
NESC9739/01 13-FEB-1987 Tested at NEADB
top ]
10. REFERENCES
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)
top ]
11. HARDWARE REQUIREMENTS

500K bytes.

top ]
12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC9739/01 FORTRAN-77
top ]
13. SOFTWARE REQUIREMENTS
NESC9739/01

VMS V4.3 (VAX-11/780).

top ]
15. NAME AND ESTABLISHMENT OF AUTHORS

         A.J. Garrett
         Savannah River Laboratory
         Aiken, South Carolina 29808

top ]
16. MATERIAL AVAILABLE
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
top ]
17. CATEGORIES
  • R. Environmental and Earth Sciences

Keywords: Monte Carlo method, air pollution, diffusion, flow models, surface air, topography, turbulence, weather.