Last Updated October 18, 2019
CTRAN/W is a finite element CAD software product that can be used to model the movement of contaminants through porous materials such as soil and rock. The comprehensive formulation of CTRAN/W makes it possible to analyze problems varying from simple particle tracking in response to the movement of water, to complex processes involving diffusion, dispersion, adsorption, radioactive decay and density dependencies. CTRAN/W can be applied to the analysis and design of geotechnical, civil, hydrogeological, and mining engineering projects.
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.
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.
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.
CTRAN/W can model equilibrium sorption and first-order reactions such as radioactive decay, biodegradation, and hydrolysis.
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 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.
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.
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.
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.
CTRAN/W can model almost any contaminant transport problem, including:
CTRAN/W offers simple but powerful analytical capabilities when used in combination with other GeoStudio products.
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 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.
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.