On The Development of A Two-way Nesting Method In Air Pollution Modelling
Abstract
Computer limitations and time consuming calculations make high grid resolution in air pollution modelling not affordable over a large area. To avoid the problem and to improve numerical accuracy, passive embedding methods are often used. Neverthe- less, these methods, also called one-way nesting methods, do not allow any feedback from fine to coarse resolutions of the simulated flow or dispersion process. In order to see the influence of finer resolutions over coarse areas, more advanced decomposition methods can be applied. Using a finite volume formulation of the transport problem, such a decomposition method, known as two-way nesting, has been developed and is presented here. The presented two-way nesting algorithm relies on mass flux continu- ity at the interface. The scheme is positive, monotonic and mass conservative. Auto- matic procedures have been implemented to perform the calculation over the whole grid architecture and to simplify the management of a large number of variables. Grid synchronization and asynchronization procedures have been also implemented to opti- mize transport time steps according to the Courant-Friedrich-Levy condition imposed by the grid resolution. Results are presented on various ideal test cases. The tech- nique was specifically developed for air pollution applications although its use can be extended to the numerical treatment of other advection-diffusion processes in geo- physical sciences.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.2894W