Last Updated October 18, 2019

Overview

AIR/W is a finite element CAD software product for analyzing groundwater-air interaction problems within porous materials such as soil and rock. Its comprehensive formulation allows you to consider analyses ranging from simple, saturated steady-state problems to sophisticated, saturated/unsaturated time-dependent problems. AIR/W can be applied to the analysis and design of geotechnical, civil, hydrogeological, and mining engineering projects.

Key Features

DENSITY DEPENDENT AIR F LOW

AIR/W can be integrated with TEMP/W to model air transfer via free convection. Density-driven air transfer is often a dominant mechanism in systems subjected to seasonal ground temperature variations.

ESTIMATE MATERIAL PROPERTIES

The air conductivity function can be estimated given the dry-soil air conductivity, a user-selected volumetric water content function, and basic soil properties, such as the soil classification or grain size distribution.

FORCED-CONVECTION HEAT TRANSFER

Combine AIR/W with TEMP/W to model forced-convection heat transfer. This process often governs the thermal regime in coarse-grain materials such as waste rock piles, rip-rap, and layered embankments.

SINGLE OR DUAL PHASE FLOW

Air transfer analyses can be conducted using a single phase material model that only considers pressure and gravity-driven air flow. Alternatively, a dual phase material model can be used by coupling air flow and water transfer.

AIR/W models a full range of air transfer problems

THERMAL RESPONSE OF GRAVEL EMBANKMENTS

Forced convective heat transfer through coarse grain embankments may occur as a result of air movement. In northern regions, convection can cause significant temperature reduction within an embankment during winter months. Conversely, convection through the embankment during summer months may affect permafrost within the underlying formation. When coupled with TEMP/W, AIR/W may be used to investigate these effects.

DESIGN OF WASTE COVER SYSTEMS

Cover systems for mine waste, landfills, and mine reclamation often involve complex hydraulic behaviour that effect long-term performance of these structures. AIR/W may be coupled with SEEP/W to understand the movement of air and water through saturated-unsaturated cover systems. A cover analysis may also include gas migration when AIR/W is coupled with CTRAN/W.

GAS PARTICLE MOVEMENT IN POROUS MEDIA

The single phase AIR/W material model allows for the simulation of pressure driven air flow. In a single phase simulation, the particle tracking option may be selected to evaluate gas particle movement through the porous medium.

DENSITY EFFECTS ON AIR FLOW

Air movement through porous media may be influenced by spatial variations in temperature, causing density-dependent air flow, or free convection. Together, AIR/W and TEMP/W can simulate air flow generated by density differences throughout the domain.

VIEWING THE ANALYSIS RESULTS

Once you have solved your seepage problem, AIR/W offers many tools for viewing results. Generate contours or x-y plots of any computed parameter, such as head, pressures, matric suction, gradients, velocities, and conductivities. Air or water velocity vectors show flow direction and rate. Transient conditions can be shown as a changing water table over time. Interactively query computed values by clicking on any node, 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

AIR/W can model almost any groundwater problem, including:

  • Soil vapor extraction systems
  • Air pressure in tunnels for support and water inflow control
  • Air pressure response ahead of water infiltration fronts
  • Thermal / density dependent air flow that contributes to convective heat transfer in freezing / thawing soils (when coupled with TEMP/W)
  • The true matric suction (Ua-Uw) phenomenon
  • plus many more!

The Power Of Integration

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

INTEGRATED WATER TRANSFER WITH SEEP/W

Coupled air-water systems can be modeled by coupling SEEP/W and AIR/W via the matric suction (the difference between pore-air and pore-water pressures). A change in air pressure will cause a change in the water pressure and vice versa. This is useful for modelling mine closure cover systems or water/air movement in acid generating waste rock.

DENSITY DEPENDENT FLOW WITH TEMP/W

Density-dependent fluid flow forms when temperature variations cause significant density differences. Air movement in turn influences the temperature distribution throughout the domain. A coupled AIR/W and TEMP/W analysis allows for the simultaneous simulation of heat and air movement associated with density-dependent flow.

AIR/W RESULTS IN TEMP/W

One of the major components of heat flow analyses in unsaturated materials is air flow, as it causes forced convection heat transfer. Combining AIR/W and TEMP/W analyses allows for a comprehensive assessment of heat transport in unsaturated porous media.