1. General Model Information
Name: Finite-difference model of multi-compound vapor transport and phase distribution
Main medium: terrestrial
Main subject: hydrology, biogeochemistry
Organization level: ecosystem
Type of model: partial differential equations (finite differences,2D)
Keywords: multi-compound, vapor transport,NAPL,advective and diffusive fluxes
David A. Benson
Dept. of Geol. Sci./172
University of Nevada
Reno, NV 89557-0138
Phone: (702) 784-4986
VENT2D is a two-dimensional, finite difference, multi-compound vapor transport and phase
partitioning model. The program solves the vapor-phase advective and diffusive fluxes of up to 60
compounds in a 35 x 35 grid. The chemical compounds can partition into the vapor, dissolved,
adsorbed and (if concentrations are high enough at a given location) a nonaqueous phase liquid
(NAPL). Since the NAPL means non-linear sorption, the phase distribution must be explicitly
calculated at each node between vapor movement timesteps. Henry's Law dictates phase
partitioning without NAPL, while Raoult's Law is used when NAPL is present. The vapor is
assumed to be the only mobile phase. The 2-D grid can be given any distribution of permeability
and initial contaminant concentrations. The model continuously tracks the water and NAPL
saturations to update the soil-gas permeability, pressure and flow fields. The 2-D grid also allows
spatially-variable leakage of clean air from the third dimension into the model domain (simulating
a bare ground surface, for example). The transport code was developed specifically for vapor
movement and is much faster than an equivalent groundwater transport code. Since vapor
diffusion is usually much more dominant than hydrodynamic (aerodynamic?) dispersion, the
simpler diffusion is solved exclusively. Of course, the diffusivity is saturation dependent. Extraction
or injection wells can be specified at any grid location. A spreadsheet containing the chemical
characteristics (required by VENT2D) of gasoline hydrocarbons and other organic compounds is
provided in the acces.zip file.
Source of the abstract: VENT2D Home Page
II. Technical Information
Operating System(s): DOS
VENT2D FTP-Site This software is presented AS IS, with no warranty, expressed or implied. If you accept this agreement, you may freely download the 486/Pentium VENT2D version 2.4 (~150K) and retain the rightful use of the software. The latest version was compiled and made available 07 August 1997. I gratefully invite your comments, but support of VENT2D will not be automatically given by the author. Purchasers of VENT3D will receive full support.
This is a zipped version of a PostScript file of the User's Manual to VENT2D (~137K). You must have a PostScript printer to make any use of this file. If you do not have access to a PostScript printer, send $20 for production and shipping costs to the author. A bound copy will be sent to you.
input data file (~9K) that is required by the model, along with the two output files that VENT2D creates. The 3 files are zipped together.
(acces.zip ~53K) contains a number of executables that are accessories to the VENT2D package. It includes sample input files, utilities that translate VENT2D output directly to SURFER (TM) format grid files, and a spreadsheet that contains the chemical data for many common contaminants and the published compositions of fresh and weathered gasoline. Full documentation is provided in the VENT2D User's Manual.
III. Mathematical Information
Benson, D. A., D. Huntley, and P. C. Johnson 1993 Modeling vapor transport and general transport in the presence of NAPL mixtures and nonideal conditions, Ground Water, volume 31, number 3, pp. 437-445.
V. Further information in the World-Wide-Web
brochure about VENT2D
VI. Additional remarks
Last review of this document by: T. Gabele: Wed Oct 8 1997