CTRAN/W

Solute and gas transfer analysis

CTRAN/W is a powerful finite element software product for modeling solute and gas transfer in porous media. CTRAN/W can be used to model simple diffusion-dominated systems through to complex advection-dispersion systems with first-order reactions.

CTRAN/W can be used to model a vast array of geo-environmental problems involving the movement of dissolved species or gases that originate from either man-made or naturally occurring sources.


Key Features

Comprehensive Formulation

CTRAN/W offers the capability to model a diverse set of solute and gas transport mechanisms including diffusion, advection, dispersion, adsorption, decay, and density-dependent flow due to its comprehensive formulation.

Dual Phase Gas  Transfer

CTRAN/W models gas transfer in both the gaseous and aqueous phases. A bulk diffusion coefficient, longitudinal dispersivity, and transverse dispersivity are defined for each phase.

 


Saturated and Unsaturated

CTRAN/W is formulated for saturated and unsaturated transport, allowing the coefficient of diffusion to vary with water content and the advection process to adjust as groundwater velocities change in the unsaturated zone.

 


Sorption and Kinetic Reactions

CTRAN/W can model equilibrium sorption and first-order reactions such as radioactive decay, biodegradation, and hydrolysis.

 


CTRAN/W can model almost any contaminant transport problem

Download GeoStudio to view GSZ files

Caesium 137 Transport

Caesium-137 (Cs-137) is an anthropogenic radioactive isotope formed as a product of nuclear fission. The objective of this example is to analyze Cs-137 transport into an unconfined aquifer using CTRAN/W. The effect of adsorption and decay on solute concentrations and mass discharge is highlighted.

Download the GeoStudio data files
Read the analysis details

Transport and Consumption of Oxygen in Cover Material

The objective of this example is to analyze oxygen transport through an unsaturated cover system and explore the effectiveness of oxidation within the water retention unit.

Download the GeoStudio data files
Read the analysis details

Effects of Salt Concentration on Water Flow

This example demonstrates a water transfer analysis influenced by solute concentration effects (i.e., density-dependent flow).

Download the GeoStudio data files
Read the analysis details

Source and Exit Boundary Conditions

This example demonstrates the use of four boundary conditions in CTRAN/W, including constant concentration, source concentration, free exit mass flux, and total mass flux of zero.

Download the GeoStudio data files
Read the analysis details

CTRAN/W's intuitive modeling workflow

Create a CTRAN/W analysis and set up the problem workspace. Choose the analysis type from: steady-state solute, transient solute, steady-state gas and transient gas transfer. Define the initial pore-water pressure and concentration conditions, convergence criteria, and time duration and increments.

Draw the regions in your domain using CAD-like drawing tools, including drawing polygon and circular regions, coordinate import, copy-paste geometric items, length and angle feedback, region splitting and merging, and direct keyboard entry of coordinates, lengths, and angles. Alternatively, import AutoCAD DWG or DXF files directly into GeoStudio to create your domain geometry.

Define the material properties for your analysis, assign them to regions on the domain, and then define your initial concentration conditions. Define advection, dispersion or diffusion properties and add optional decay half-life. Define the initial seepage and concentration conditions for transient scenarios using results from other SEEP/W or CTRAN/W analyses or defined spatial functions.

Define concentration boundary conditions to simulate concentration, mass flux (q), mass rate (Q), source concentration, or free exit mass flux conditions. Time-varying conditions can also be modeled.

Open Draw Mesh Properties to refine the mesh drawn on the entire domain, or along specific geometric regions, lines or boundaries.

When your problem is completely defined, start the analysis process in the Solve Manager window. The Solve Manager displays the solution progress, allowing you to cancel or stop/restart if necessary. While the solution is in progress, you can look at preliminary results in the Results window.

When the Solver is finished, the concentration contours are displayed. Velocity vectors and the phreatic surface can also be viewed on the domain using results from the associated SEEP/W analysis. You can display other contours using the Draw Contours window, including pore-water pressure, material properties, water flow, and gradients. Contour legends and properties can also be modified. Labels can be added to contour lines in Results View.

Interactively select any node or gauss region to view result information, including concentration, mass flux, material properties, and more. Display plots of computed results over the x- or y-direction or create time-varying plots of results in transient analyses, such as concentration, mass flux, cumulative mass and more. Generate reports of the definition and results, and export into other applications such as Microsoft Excel for further analysis.

The power of integration

CTRAN/W offers simple but powerful analytical capabilities when used in combination with other GeoStudio products.

CTRAN/W CTRAN/W

SEEP/W results in CTRAN/W

One of the major components of solute and gas transport analyses is pore-water velocity, which can be simulated in SEEP/W. Combining CTRAN/W and SEEP/W analyses allows for a comprehensive assessment of solute and gas transport in porous media.

Density-Dependent Flow

 

In density-dependent fluid flow, the solute or gas concentration affects the density of water, which influences pore-water velocity. Meanwhile, pore-water velocity influences the movement of the solute or gas. Thus, SEEP/W and CTRAN/W analyses are interdependent in this case. The iterative transfer of information from SEEP/W to CTRAN/W, and vice versa, allows for the simulation of density-dependent fluid flow.