CTRAN/W

Πρόγραμμα Ανάλυσης Μεταφοράς Ρυπαντών με Πεπερασμένα Στοιχεία


CTRAN/W is part of an integrated suite of five geotechnical software packages being used extensively throughout the world on six continents and in more than 70 countries. They are used by practicing engineers for the analysis and design of a wide variety of structures and by universities for teaching and research. The five state-of-the-art software packages for geotechnical modeling in the Microsoft Windows environment are:

CTRAN/W models contaminant transport through soil and rock. The comprehensive formulation of CTRAN/W makes it possible to analyze a wide range of problems. Problems may be as simple as tracking particles in response to the movement of water or as complex as analyzing processes involving diffusion, dispersion, adsorption, and radioactive decay.

More computed parameters such as concentration can be contoured. The total advective, dispersive, stored, and decayed flux can be displayed on the flux section.

CTRAN/W is integrated with SEEP/W and has the same Microsoft Windows CAD-like graphical user interface as SEEP/W. The two software products must be used together to analyze contaminant transport. SEEP/W computes the water flow velocity, water content, and water flux. CTRAN/W uses these parameters to compute the contaminant migration.

TRANSPORT PROCESSES

When a contaminant enters the ground, the dissolved constituents will migrate due to the movement of the water. This process is called advection. In addition, the contaminant disperses due to hydrodynamic mixing and molecular diffusion. In the absence of dispersion, the dissolved mass would migrate as a "plug" at full concentration. The migration also may be retarded due to adsorption and radioactive decay.
CTRAN/W has a finite-element SOLVE function to analyze advection-dispersion processes with optional mass losses due to adsorption and decay, as well as a TRACK function to model only advection.

In an advection-dispersion analysis, a user-defined concentration can be contoured for each time step on a single plot.

ADVECTION-DISPERSION

The integration with SEEP/W makes it possible to model contaminant transport for:

Advection and dispersion affect the contaminant concentration.

CTRAN/W features specific to mass transport analysis include:

PARTICLE TRACKING

CTRAN/W can model contaminant movement by tracking data points (particles) from user-defined locations. You can place a particle anywhere in the flow system by clicking at a particular point. After TRACK has moved the particles within the flow system, CONTOUR displays the particle migration paths. Particles are tracked as they move forward from the source; alternatively you can introduce particles at the sink or exit point and track them "backward" to the source. This allows you to establish the origin of the contaminant from a known exit point. The region between any two particle migration paths can be shaded to highlight the contaminated region. Specific information about a particle's migration can be displayed by clicking at any point along the computed particle migration path.

VIEWING AND PLOTTING

Variables that can be contoured and graphed include: Concentration; Total, fluid, and solid mass; Adsorption; Peclet and Courant numbers; Dispersive coefficients; and Flow velocities. CONTOUR allows you to display the total accumulated mass in the system including the portion in the fore fluid and the portion adsorbed by the soil particles. You can also display the accumulated mass within any element or any group of elements.

The purely-advective component of contaminant migration can be analyzed by tracking the movement of particles. The particle travel time, distance traveled, and average speed can be displayed at any point along the particle migration path.

Computed parameters can be plotted as a function of time or space.

CTRAN/W Version 4 Enhancements


Version 4 of CTRAN/W provides a leap into the world of 32-bit computing and advanced Windows environments. Version 4 is 32-bit software that runs under Windows 95 and Windows NT allowing you to analyze your problems faster and easier.

Density-Dependent Transport Analysis
For problems where the density of the contaminant is significantly different than water, CTRAN/W has the capability of performing density-dependent transport analyses. This feature is useful for solving problems related to sea water intrusion, brine transport and landfill leachate migration. CTRAN/W SOLVE performs density-dependent transport analyses by running SEEP/W SOLVE and solving the coupled groundwater flow and contaminant transport governing equations simultaneously using an iterative procedure within each time step. The analysis can be applied to both saturated and unsaturated soils.

Improved User Interface

Online Help and User's Guide
Unlimited Number of Time Steps
There is no longer any limit on the number of time steps that you can use in a problem.

Improved Particle Tracking
SOLVE now automatically calculates the time increment used to move the particle through the flow system. This time increment will always satisfy the Courant number criterion. As a result, particles are moved correctly, regardless of the size of the user-specified time increments. In Version 3, the particle was tracked linearly between each user-specified time increment, causing the particle to deviate from its true path when the specified time increment was too large.

Improved Contour Shading

Color Selection for Soil Layers
You can now assign a specific color to each material. CTRAN/W uses these colors when it displays the element shading. You can choose any color you wish.

Improved Mesh Generation
Version 4 allows you to generate finite elements within a triangular region, not just a quadrilateral region. CTRAN/W fills most of the triangular region with quadrilateral elements; triangular elements are generated along the third side of the triangular region.
You can now specify an element size distribution within the quadrilateral or triangular region. This allows you to increase the size of the elements from one part of the region to another.
The Multiple Elements dialog box allows you to see the generated elements before you decide to accept them. This allows you to experiment with the element generation parameters until you are satisfied with how the elements appear; you can then accept the generated elements or cancel the operation.

Graphical Modification of Problem Geometry
The Version 3 Delete and Move commands have been replaced with a single Modify Objects command in Version 4. Modify Objects is a powerful command that allows you to select any combination of objects on the drawing and then move, re-size, or delete them. Object types include text, lines, circles, arcs, flux sections and scaled axes. If you wish to modify nodes and elements, you can use the Modify Objects command in SEEP/W Version 4 and them re-import your mesh into CTRAN/W.

Plan View Infiltration
For a plan view analysis, you can now specify a unit mass flux boundary (qm) condition at any node; SOLVE computes the contributing area of the node and then computes the resulting total nodal mass flux (Qm) at the node.

Initial Concentration Definition
If you know the initial concentration at all nodes, you are no longer required to first perform a one time step advection-dispersion analysis. In DEFINE, you can now specify the initial concentration value at any node; SOLVE uses these values as the initial concentrations for the analysis.

Exit Review Boundary
You can now specify mass flux type (qm, Qm and Cs) boundary nodes as an exit review boundary. SOLVE reviews these nodes for exit conditions and automatically converts them to free exit boundaries when required. This feature is useful for solving problems with transient boundary conditions that may change certain nodes to free exit conditions during the transport process.

Other Changes

Requirements

486/Pentium (Pentium recommended) with 16 MB RAM and FORTRAN Compiler. Any Workstation, e.g., IBM RS6000, DEC Alpha, Silicon Graphics, Sun SparcStation, and HP 9000 Series.

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Incredible NetworksΤελευταία Ενημέρωση 27 Ιουλίου 2004 - Last Revised on July 27th 2004
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