CTRAN/W – Otte International

CTRAN/W

Key Features

List of CTRAN/W Features

Rigorous diffusion-dispersion formulation

Model sorption and kinematic reactions

Convenient initial condition definition

Ability to model solute and gas transfer

Complete range of boundary conditions

Seamless integration with SEEP/W and AIR/W

Formulated for saturated and unsaturated soils

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.

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.

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.

SORPTION AND KINETIC REACTIONS

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

CTRAN/W MODELS SOLUTE AND GAS TRANSFER PROBLEMS

MIGRATION AND REMEDIATION OF CONTAMINANTS

CTRAN/W provides a range of approaches for assessing the migration of gases and solutes through porous media, including simple diffusion-only transport or when coupled with SEEP/W, complex advection-dispersion and density-dependent problems. The transient formulation, sophisticated boundary condition options, and ability to include kinematic reactions and/or adsorption, also allow for the evaluation and design of remediation systems.

SEAWATER INTRUSION INTO COASTAL AQUIFERS

Seawater intrusion into coastal aquifers is an increasing issue due to both anthropogenic and natural forces. When coupled with SEEP/W, CTRAN/W can simulate the movement of salt water via advection-dispersion with groundwater flow, for example, due to inland drawdown. Spatial variation in salt concentrations may also contribute to groundwater movement via density-dependent flow. CTRAN/W may be coupled with SEEP/W as well as TEMP/W, to assess the potential for density-dependent flow to contribute to seawater intrusion.

COVER DESIGN FOR ACID ROCK DRAINAGE

Acid rock drainage (ARD) results from the disturbance and consequent oxidation of sulfide minerals. Water flowing through an acidic medium transports the ARD via advection-dispersion. Thus, covers are used to limit the exposure of oxygen and/or water to rock or waste piles containing sulfide minerals. CTRAN/W can assess oxygen ingress through a cover system via free phase and dissolved phase transport with consideration to oxygen consumption.

DESIGN OF LINER SYSTEMS

Liners are often used to minimize the movement of solutes from municipal or industrial waste storage facilities to underlying hydrogeological systems. Diffusive mass transport is generally the dominant mass transport mechanism in liners with very low hydraulic conductivities. CTRAN/W can be used to simulate diffusive mass transport, or may be coupled with SEEP/W to determine the sensitivity of mass transport through the liner due to its hydraulic conductivity.

VIEWING THE ANALYSIS RESULTS

After solving your contaminant transport problem, CTRAN/W offers many tools for viewing results. Generate contours or x-y plots of any computed parameter, such as concentration, mass, adsorption, dispersion, or Peclet and Courant numbers. Velocity vectors show the flow direction and rate. Examine the contaminant mass in the solid and liquid phases at any location. Transient conditions can be shown by plotting the changing concentration levels over time. Interactively query computed values by clicking on any node, element Gauss region, or flux section. Then prepare the results for your report by adding labels, axes, and pictures, or export the results into other applications such as Microsoft® Excel® for further analysis.

TYPICAL APPLICATIONS

CTRAN/W can model almost any contaminant transport problem, including:

Flow of contaminants from a surface pond
Flow of dissolved hydrocarbons
Flow of radioactive contaminants
Transport through fractured rock

Sea-water intrusion into coastal aquifers
Brine transport
Landfill leachate migration
plus many more!

THE POWER OF INTEGRATION

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

INTEGRATED SOLUTE AND GAS TRANSFER WITH 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 WITH CTRAN/W

Density-dependent fluid flow forms when solute or gas concentration variability causes significant density differences. Fluid movement in turn influences the domain distribution of solutes or gases. A coupled CTRAN/W and SEEP/W analysis allows for simultaneously simulating solute/gas and water movement associated with density-dependent flow.

INTEGRATED HEAT, WATER AND GAS TRANSFER

Water, energy and gas transfers within the unsaturated zone are often complex and inter-related processes. TEMP/W coupled with SEEP/W and CTRAN/W can simulate these processes and provide insight on vadose zone hydrology.

Details

FORMULATION

When a contaminant enters the ground, the dissolved constituents will migrate due to the movement of the water. In addition, the contaminant disperses due to hydrodynamic mixing and molecular diffusion. The migration also may be retarded due to adsorption and radioactive decay. The advective-dispersive differential equation is derived by applying the principle of mass balance to an element of porous medium, with consideration of advection, dispersion, adsorption and decay.

CTRAN/W computes adsorption using the adsorption function and the computed nodal concentrations. It then computes the mass quantity in both the fluid phase and the solid phase.

CTRAN/W can also model contaminant movement by simply tracking particles from user-defined locations. For each time step, CTRAN/W moves the particles a distance based on the volumetric water content and the SEEP/W-computed water velocities.

FEATURES

Steady-state and transient water flow conditions through saturated and unsaturated soil systems.
Time-dependent hydraulic boundary conditions.
Anisotropic and heterogeneous ground conditions.
Time-dependent concentration and mass flux boundary conditions, free exit boundary conditions.
Molecular diffusion coefficient as a function of volumetric water content.
Model adsorption as a function of concentration, mass loss due to radioactive decay, and mass flux across user-specified sections.
Particle tracking isolates advection by showing the flow path of individual particles.
Density-dependent analysis with contaminant density different than groundwater density.
And many more!

INTEGRATION WITH OTHER APPLICATIONS

USE SEEP/W OR VADOSE/W VELOCITIES IN CTRAN/W

One of the major components in a contaminant transport analysis is the velocity of the water, which can be obtained from a SEEP/W or VADOSE/W analysis. Once this velocity is known, it can be used in CTRAN/W to study the transport of contaminants.

PERFORM DENSITY DEPENDENT ANALYSES WITH CTRAN/W AND SEEP/W

In density dependent fluid flow, the velocity of the water is dependent on the solute concentration. The water velocity in turn influences the movement of the solute. The iterative transfer of water velocity from SEEP/W to CTRAN/W and the transfer of concentration from CTRAN/W to SEEP/W makes it possible to do density dependant fluid flow analyses.

ENGINEERING METHODOLOGY BOOK

The included CTRAN/W engineering methodology book discusses the whys and hows of modeling, as well as the theory and formulations behind the CTRAN/W product. Transport Modeling with CTRAN/W is a full-length book about proper modeling techniques: how to think before, during and after setting up and solving a model. The book includes chapters devoted to:

Material Properties
Bounday Conditions
Analysis Types
Functions in GeoStudio
Numerical Issues
Visualization of Results
Modeling Tips and Tricks
Illustrative Examples
Theory

Technical Specifications

MINIMUM SYSTEM REQUIREMENTS

Microsoft® Windows® 10, Windows® 8.1, Windows® 8, Windows® 7 SP1
Intel® Pentium® 4 or better, or AMD Opteron™ or Athlon™ 64 or better. (GeoStudio is optimized for multi-core Intel processors)
1 GB hard disk space
1024×768 screen resolution.
For 3D features, your graphics card must support Direct3D® Feature Level 10_1 or greater.
This includes graphics cards such as (and newer than):
- Nvidia® GT 300
- ATI® Radeon® HD 4000 Series
- Intel® HD Graphics 3000/2000
Microsoft® .NET 4.0 will be installed automatically if it is missing.

SUPPORTED VIRTUAL MACHINES

The latest release of GeoStudio can be run on these VM platforms:

VMware® ESXi™ 5.5 and 6.0
VMware® Workstation™ 11 and 12
Microsoft® Hyper-V® on Windows Server® 2016, 2012 R2, 2012, and Windows® 10
Citrix® XenServer® 6.2, 6.5 and 7.0

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