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Scale dependent nitrogen dynamics in forests
BMBF PT BEO 510339476 C BITÖKC 5From 01/1998 to 06/1999
Principal Investigator: Bernd Huwe
Staff: Hans Piehler
Grant: 0339476 C Grundlagen zur nachhaltigen Entwicklung von Ökosystemen bei veränderter Umwelt
This report is concerned with the problem of the simulation of water and solute transport in heterogeneous porous media. We differentiate thereby between the analytic and the numeric aspects of the problem. The analytic aspects represent the respective theoretical background, the numeric aspects direct at the implementation of the theoretical considerations on a computer.
The physical and chemical characteristics of heterogeneous media are idealized frequently as random fields with given statistical characteristics. Therefore we will consider first the numeric generation of such fields on the computer. The heterogeneous media considered here are assumed as Miller similar, so that the water tension and the conductivity can be calculated from the similitude theory after Miller and Miller (1956). The calculation of the heterogeneous stationary flow field on the basis of the Miller theory is described and the solute transport with the diffusion advection equation in the heterogeneous stationary flow field is shown. Finally the transition from the diffusion advection equation to a Ito stochastic differential equation is performed. At the end the structure of a simulation program is described, with which the presented theories were implemented.
