GGU-CONTAM-FE: Program concept

The flow field is required in order to model contaminant propagation (velocities with magnitude and direction). GGU-CONTAM-FE acquires this initial condition from a record (e.g. "plgw.da1") generated during a previous modelling using the GGU-2D-SSFLOW application. It is therefore necessary to load this file first after opening the program. The flow field contained in this file remains constant for subsequent calculations.

Besides the flow field, the GGU-CONTAM-FE program requires information on the initial contaminant distribution conditions at time t = 0. These so-called initial concentrations can be arbitrarily defined. If you do not define any values, the program will assume an initial concentration of '0' at all nodes.

Apart from the flow field, the "plgw.da1" example file also includes the effective pore space neff, upon which steady-state modelling is based. This steady-state soil property (n_eff) cannot be altered from within the GGU-CONTAM-FE program. If amendment of this value were allowed, the flow field would no longer correlate to the computed potentials and contaminant propagation modelling would produce nonsensical results. However, additional soil properties, which are required for contaminant propagation, must be provided.

Further to these additional soil properties, time-dependent boundary conditions can also be defined with GGU-CONTAM-FE. You must define boundary values (concentration or concentration source) as a function of time, by means of polygon courses. These polygon courses can then be assigned system nodes, either individually or in groups. Soil properties (for contaminant propagation) and polygon courses, as well as their allocations to system nodes, can be saved in a separate file (known as boundary data), in order to make them available again for later modelling.

Generally, when modelling contaminant propagation, a flood of result values is generated. Modelling results are saved by the GGU-CONTAM-FE program in a file ("*_kon.plw"). Contaminant propagation data cannot be evaluated using the GGU-CONTAM-FE program. The GGU-PLGW program is available for evaluation purposes and is described in a separate user-manual.

The GGU-CONTAM-FE program is started using conventional WINDOWS operations. The program is equipped with many error queries. Nonsensical input will usually be caught by the program and an error message displayed on the screen. Independently of this you should, for security reasons, intermittently save longer input, if only to save renewed input in the case of a power cut.