AIRFLOW/SVE Description

Predict remediation cleanup times and estimate well vapor concentrations

...and graphically display the results in many different formats.

Introduction to AIRFLOW/SVE
AIRFLOW/SVE Main Features
AIRFLOW/SVE Input
AIRFLOW/SVE Built-In Data Checking
AIRFLOW/SVE Analysis
AIRFLOW/SVE Output
AIRFLOW/SVE Documentation & Support
AIRFLOW/SVE Requirements

INTRODUCTION TO AIRFLOW/SVE

AIRFLOW/SVE is a finite-difference numerical model for simulating vapor flow and multi-component vapor transport in unsaturated, heterogeneous and anisotropic soil. AIRFLOW/SVE calculates radially-symmetrical, steady-state vapor flow towards an extraction well and accounts for time-variant depletion of non-aqueous phase liquid (NAPL) organic contaminants. AIRFLOW/SVE contains a fully-integrated graphical interface, allowing the user to easily design the model, run simulations, display results, and produce report-quality output, all within the same seamless environment. The comprehensive formulation of AIRFLOW/SVE provides a rigorous treatment of the vapor flow and mass partitioning processes. In addition, AIRFLOW/SVE has extensive output display options which make it the model of choice for designing and evaluating vapor transport in the unsaturated zone, soil bioventing systems and soil vapor extraction (SVE) remediation systems.

AIRFLOW/SVE computes, for a vertical cross section, the steady-state vapor pressure distribution, velocities, and pathlines for an ideal, single phase, compressible gas. Different gases are simulated by specifying different gas constants, gas molar masses, and viscosities. AIRFLOW/SVE accounts for temperature and pressure-dependent gas density. The model domain can be made up of heterogeneous and anisotropic permeability zones. Along any one of the model domain's boundaries, constant pressure or constant flux (including impermeable conditions can be imposed.

AIRFLOW/SVE overcomes major limitations of other commercial vacuum extraction models: volumetric gas flow rates are calculated directly by the model and vary spatially; the NAPL can be present in the form of residual, lenses, or pools and can be spatially distributed; and mass transfer between NAPL, water, and gas can be represented as kinetically-controlled as well as by equilibrium processes. Various types of sorption isotherms can be considered by AIRFLOW/SVE. Differential NAPL depletion can be simulated with the more volatile compounds being depleted first, leaving behind the less volatile species.

AIRFLOW/SVE uses an efficient and robust numerical solver to ensure conservation of mass and that large simulations (with several chemical components) can be analyzed quickly using a personal computer.

AIRFLOW/SVE MAIN FEATURES

AIRFLOW/SVE is the most comprehensive soil vapor flow and multi-component transport model available!

Fully Integrated User Interface:

• design and build the model
• run the simulation (flow/transport/pathlines)
• visualize and output results
• on-line database of chemical properties for 75 common organic contaminants

Comprehensive Formulation:

• rigorous treatment of the soil-water-NAPL vapor partitioning processes
• efficient algorithms and robust numerical methods assure conservation of mass
• run the simulation (flow/transport/pathlines)
• visualize and output results
• calculate volumetric flow rates
• heterogeneous-anisotropic soil conditions
• irregular spatial distribution of NAPL

This is a "must have" tool for designing and evaluating soil vapor extraction and bioventing remediation systems.

AIRFLOW/SVE INPUT

AIRFLOW/SVE is a fully-integrated modeling package whereby all of the data input is done graphically through an interactive, user-friendly interface:

• The model grid can be graphically modified by adding or deleting the desired rows or columns.
• Wells can be fully or partially screened in the unsaturated zone.
• Well conditions can be specified as either a vacuum pressure or as a volumetric vapor extraction rate.
• Impermeable ground cover can be assigned over a specified radius around the well.
• Heterogeneous soil layers are assigned by stretching a window across the desired depth interval.
• NAPL properties are assigned with a single keystroke using an on-line database of 75 organic contaminants.
• Irregular zones of NAPL distribution (vapor, residual or pools) can be graphically assigned by stretching a window around the specified area.
• Forward and backward pathline origins are graphically assigned.

AIRFLOW/SVE BUILT-IN DATA CHECKING

As you specify your model and just prior to the data analysis, the program automatically checks your input data for errors. If there is an error with your input data, AIRFLOW/SVE will explain what is wrong and how to correct it. As a result of this detailed input error checking, input of faulty data is almost entirely eliminated.

AIRFLOW/SVE ANALYSIS

AIRFLOW/SVE overcomes the major limitations of other commercial SVE models by considering vapor flow through heterogeneous and anisotropic soil with variable water contents, and by implementing a rigorous treatment of the partitioning processes which occur between the soil, aqueous, NAPL and vapor phases. In addition:

• Volumetric flow rates in the well are calculated directly by the model for a specified well vacuum pressure.
• Mass transfer between NAPL, water, soil and vapor can be represented as kinetically-controlled or as an equilibrium process.
• Different types of equilibrium sorption isotherms can be simulated.
• Differential NAPL mass depletion is simulated, with the more volatile compounds extracted first.
• Pressures and flow velocities recalculated as the NAPL mass is depleted.

With AIRFLOW/SVE, the efficient algorithms and robust numerical methods assure conservation of mass for the vapor and NAPL for large simulations with several different chemical components.

AIRFLOW/SVE OUTPUT

AIRFLOW/SVE comes complete with high-quality post-processing capabilities for displaying results (see graphics) and outputting them to a printer, plotter or graphics file. The extensive display options include:

• Steady-state vapor pressure contours, velocity vectors and pathlines.
• Isoconcentration contours for soil contamination.
• Graphs of well vapor concentration vs. time, cumulative vapor extraction rates, and contaminant mass extracted or remaining.
• Logbook summary of input model parameters.

These results can be sent to most printers and plotters and can be exported to various graphics file formats (DXF, PCX, EPS, TIF, GlF, etc.).

AIRFLOW/SVE DOCUMENTATION & SUPPORT

AIRFLOW/SVE includes a comprehensive user's manual with a summary of the underlying theory and equations, easy-to-follow instructions and an example problem with step-by-step instructions. Free technical support is provided via phone, fax and e-mail.

AIRFLOW/SVE REQUIREMENTS

Pentium with 4 MB RAM and 10 MB free disk space.

AIRFLOW/SVE Overview
AIRFLOW/SVE Detailed Description
AIRFLOW/SVE Prices

Scientific Software Group    P.O Box 708188    Sandy, Utah 84070
Phone (801) 208-3011   Toll Free (U.S.) 1-866-620-9214  Fax (801) 302-1160   E-mail info@scisoftware.com
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