Mathematical Model TRIM-3D

Short Description

The mathematical model TRIM-3D is based on the finite difference method. In contrast to the two-dimensional (depth-averaged) mathematical model TRIM-2D, TRIM-3D is a fully three-dimensional model. TRIM-3D was designed to solve several transient nonlinear partial differential equations (pde's). The model is actually used to study one ore more of the following physical processes:

1. transport of water (conservation of the water mass)
2. transport of linear momentum (conservation of linear momentum)
3. transport of salinity (conservation of the dissolved salt mass)

The model takes into account hydrodynamic pressure in the water body (non-hydrostatic pressure distribution). A simplifying hydrostatic approximation can be alternatively used. This approximation might be useful for natural systems with negligible vertical accelerations (compared with gravity).

TRIM-3D was developed by Prof. V. Casulli (Trento University, Italy). In the framework of a scientific cooperation TRIM-3D has been successfully installed in the year 1996 at BAW-DHs computers. It has been integrated into BAW-DHs numerical modelling toolbox and is now used on a routine basis in the context of different real-world projects concerning estuarine flow and transport processes. Meanwhile the code of TRIM-3D has been optimized to improve performance on multiprocessor vector computers.

There exists a up to now no Standard Validation Document for TRIM-3D which would provide the potential user with information about the capabilities and limitations of the model.

Preprocessors

• Generation of Boundary Conditions
• Generation and Modification of Computational Grids

Programs for Simulation

• TR2VOR: generation of a compact version of the bathymetry-file together with some index arrays which are required during the simulation run for optimal performance on vector computers
• TR2LQ2: generation of a profile topography which is necessary to output results from a TRIM-3D simulation run along profiles
• TRIM-3D: simulation run

Postprocessors

• Conversion of Computed Results: general purpose prostprocessors for the conversion of data.
• Analysis of Calculated Results: tidal characteristic numbers, tide-independent characteristic numbers, tidal harmonic analysis and comparative analysis.
• Spread-Sheet Calculations for Computed Results: application of the spread-sheet program MS Excel (TM) to display and modify computed results.

• TR3MODATE: modification of date and time in a hydrodynamic results file if this hydrodynamic state should be used as initial state for a different date
• TR3KACHEL: generation of sections (tiles); topography as well as data are cut into pieces out of the result files for the entire computational domain for any desired section (tile).
• GVIEW2D: graphical display of time series at selected locations
• LQ2PRO: Visualization of data along profiles
• HVIEW2D: graphical display of 2D synoptic or data analyses results
• VVIEW2D: graphical representation of CFD-data for vertical sections

General Data Flow

Graphical representation of general flow of data related to a TRIM-3D application (with German text only). This graphical representation is also available in Encapsulated PostScript Format.

Example Applications

• tide independent characteristic numbers of salinity for a cross section in the Ems Estuary.
• propagation of short waves in a harbour basin (text available in German only)
• Animations of salinity and flow velocity in the Außenems estuary
• A Second Order Lagrangian Method for Large Eddy Simulation
• secondary currents in river turns, first results related to the project Minimierung der Unterhaltungsmaßnahmen im Bereich des Blexer Bogens (Lower Weser Estuary) --- available in German only

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Overview