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Finite Element Heat and Mass Transfer Code (FEHM)

The numerical background of the FEHM computer code can be traced to the early 1970s when it was used to simulate geothermal and hot dry rock reservoirs. The primary use over a number of years was to assist in the understanding of flow fields and mass transport in the saturated and unsaturated zones below the potential Yucca Mountain repository. Today FEHM is used to simulate groundwater and contaminant flow and transport in deep and shallow, fractured and un-fractured porous media throughout the US DOE complex. FEHM has proved to be a valuable asset on a variety of projects of national interest including Environmental Remediation of the Nevada Test Site, the LANL Groundwater Protection Program, geologic CO2 sequestration, Enhanced Geothermal Energy (EGS) programs, Oil and Gas production, Nuclear Waste Isolation, and Arctic Permafrost.

Subsurface physics has ranged from single fluid/single phase fluid flow when simulating basin scale groundwater aquifers to complex multi-fluid/multi-phase fluid flow that includes phase change with boiling and condensing in applications such as unsaturated zone surrounding nuclear waste storage facility or leakage of CO2/brine through faults or wellbores. The numerical method used in FEHM is the control volume method (CV) for fluid flow and heat transfer equations which allows FEHM to exactly enforce energy/mass conservation; while an option is available to use the finite element (FE) method for displacement equations to obtain more accurate stress calculations. In addition to these standard methods, an option to use FE for flow is available, as well as a simple Finite Difference scheme.


• 3-dimensional complex geometries with unstructured grids
• saturated and unsaturated media
• simulation of production from gas hydrate reservoirs
• simulation of geothermal reservoirs
• non-isothermal, multi-phase flow of gas, water, oil
• non-isothermal, multi-phase flow of air, water
• non-isothermal, multi-phase flow of CO2, water
• multiple chemically reactive and sorbing tracers
• preconditioned conjugate gradient solution of coupled linear equations
• fully implicit, fully coupled Newton Raphson solution of nonlinear equations
• double porosity and double porosity/double permeability capabilities
• control volume (CV) and finite element method (FE) methods
• coupled geomechanics (THM) problems (fluid flow and heat transfer coupled with stress/deformation) including non-linear elastic and plastic deformation, nonlinear functional dependence of rock properties (e.g. permeability, porosity, Young's modulus) on pressure, temperature and damage/stress

FEHM Documentation

The FEHM User Manual is on-line with wiki pages. These pages are the most current edition of the FEHM User Manual V3. Edits and additions to the wiki man pages can be made by any person on the FEHM Development Team.

These documents are downloadable pdf files and can be viewed and printed using a PDF reader such as Adobe Reader. The FEHM User Manual details how to use the FEHM application and is based on V3 release. Supplemental updates to selected macro control statements are documented in the User Manual Appendix.

  "User Manual for FEHM Application V3 and Supplemental Appendices "

In the following documents, Models and Methods provides numerical details for the FEHM code, and the Validation & Verification (V&V) document describe the Test Suites distributed with the FEHM executable.

  "Models and Methods Summary for the FEHM Application"

  "V&V Test Suite for the FEHM Application"

FEHM Publications

  "FEHM_LAUR-07-3359.pdf"   "FEHM: A control volume finite element code for simulating subsurface multi-phase multi-fluid heat and mass transfer" 2007 LA-UR-3359, George A. Zyvoloski

   "FEHM_references_list.pdf"   List of Peer Reviewed FEHM Publications

FEHM Code Development Team

For help or suggestions you may contact a team member directly, or use our
General Help email: fehm-help@lanl.gov

• George A. Zyvoloski, FEHM Team Leader (Retired), gaz@lanl.gov
• Shaoping Chu, Configuration control, verification, and installation, spchu@lanl.gov
• Terry Miller, Software Distribution, tamiller@lanl.gov
• Philip H. Stauffer, Multiphase flow and transport, stauffer@lanl.gov    Stauffer CV
• Rajesh J. Pawar, CO2 and Methane Hydrate, rajesh@lanl.gov
• Sharad Kelkar, Particle Tracking, kelkar@lanl.gov
• Bruce A. Robinson, Transport and particle tracking, robinson@lanl.gov
• Hari S. Viswanathan, Transport, viswana@lanl.gov
• Elizabeth H. Keating, Fluid flow and solute transport, ekeating@lanl.gov
Andrew V. Wolfsberg, Fluid flow and solute transport, awolf@lanl.gov

FEHM Distribution

FEHM is available on Linux, MacOSX and WINDOWS. Executables of FEHM are available at no cost.

Now Available: Version 3.3 Released December 2015

Register as a FEHM user here.

    (Note, the username and password is:   fehm   registration )

FEHM Versions and Release Notes

Copyright 2013. Los Alamos National Security, LLC for FEHM LA-CC-2012-083. This material was produced under U.S. Government contract DE-AC52-06NA25396 for Los Alamos National Laboratory (LANL), which is operated by Los Alamos National Security, LLC for the U.S. Department of Energy. The U.S. Government has rights to use, reproduce, and distribute this software. Neither the U.S. Government nor Los Alamos National Security, LLC or persons acting on their behalf, make any warranty, express or implied, or assumes any liability for the accuracy, completeness, or usefulness of the software, any information pertaining to the software, or represents that its use would not infringe privately owned rights.

The licensed software, FEHM, may be Export Controlled. It may not be distributed or used by individuals or entities prohibited from having access to the software package, pursuant to United States export control laws and regulations. An export control review and determination must be completed before LANS will provide access to the identified Software.

Distribution of FEHM source code is limited to FEHM team collaborators with a LANS approved and signed Contributor Agreement. Contact Terry Miller tamiller@lanl.gov or an FEHM team member for more information.

Auxiliary FEHM Programs

Fehmpytests: Fehmpytests is a new test suite for FEHM developers to easily test new code and add new tests for existing or future functionality. Fehmpytests uses the Python unittest module and a general test method that can be called for each new test case. Future plans are to integrate Fehmpytests into the FEHM build and version control process.

PyFEHM: is an open-source (LGPL 2.1) Python library that provides classes and methods to support a scripting environment for the subsurface heat and mass transfer, and geomechanics code FEHM. It is inspired by a similar library, PyTOUGH, available for use with the TOUGH2 family of codes.

WALKABOUT: performs random walk particle tracking simulations of solute transport based on groundwater flow solutions from FEHM. A typical workflow for Walkabout within the FEHM system would use LaGrit to generate unstructured grids. FEHM then provides a discretized representation of the steady-state flow field to Walkabout. Given this discrete solution, Walkabout then reconstructs a groundwater flow field, and performs the random walk particle tracking calculation.

PlumeCalc: implements the Convolution-Based Particle Tracking (CBPT) method and requires auxiliary input information related to the flow and transport model as provided by FEHM.

Auxiliary Grid-Generating Programs

LaGriT Grid Generation ToolBox is LANL authored Mesh generation software for geological applications. LaGriT writes mesh and model setup files appropriate for use by FEHM. LaGriT Meshing for geologic applications can be found on the project pages, https://meshing.lanl.gov .

GRIDDER: is rectangular grid generator that creates structured grids in a format used by FEHM.

Auxiliary Grid Viewing Programs

GMV, General Mesh Viewer is an easy to use, 3-D scientific visualization tool designed to view simulation data from any type of structured or unstructured mesh.


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