Python is an open-source, object-oriented scripting language with extensive functionality, a large, active development community and loads of online resources for troubleshooting. PyFEHM is a set of classes and methods to enable use of FEHM and auxiliary tasks within the Python scripting environment. Briefly, PyFEHM functionality includes

  1. Unstructured/structure grid parsing, structured grid generation and manipulation (see Chapter 2).
  2. FEHM input file construction. Support for many macros, restart files, stress and carbon dioxide modules (see Chapter 3).
  3. Post-processing of output (see Chapter 4), including visualisation in Paraview.
  4. Scripting tools that supports Python’s built-in multi-processing capabilities for batch simulations.

Introductory tutorials to PyFEHM are also provided.



PyFEHM is supported on Python 2.6 and 2.7, but NOT 3.x. Instructions for downloading and installing Python can be found at

PyFEHM requires the following Python modules to be installed: NumPy, SciPy, Matplotlib. For windows users, 32- and 64-bit installers (for several Python versions) of these modules can be obtained from


A download link for the latest release version of PyFEHM can be found at

To install, download and extract the zip file, and run the setup script at the command line:

python install


The purpose of PyFEHM is construction of input and grid files for running FEHM simulations. Therefore, if the user does not have a copy of FEHM, their experience with PyFEHM is likely to be short and unsatisfactory.

Downloading PyFEHM does not provide the user with an FEHM executable. FEHM is free, but controlled, software and must be obtained by registering as a user at


Paraview is a parallel, open-source visualisation software. PyFEHM supports a bridge with Paraview; information about the grid, model, and output data can be automatically exported and viewed in this program.

Instructions for downloading and installing Paraview can be found at

After installation, make sure to include the path to paraview.exe in you PATH environment variable. This will ensure PyFEHM can find Paraview and make full use of its capabilities.


LaGriT is a mesh generation package, developed at Los Alamos, with a variety of tools for creating and modifying tetrahedral meshes. PyFEHM requires an executable of LaGriT to perform some specialised tasks. For more information on obtaining a LaGriT executable, visit

Using PyFEHM

PyFEHM consists of several Python modules. To access their functionality, the user must include the following line at the top of any Python script

from fdata import*

A configuration file, pyfehmrc, can be used to customise your installation of PyFEHM. For instance, default paths to FEHM or Paraview can be defined in the config file to avoid having to write these out in scripts. Other default behaviour in PyFEHM can also be modified by making changes to the config file.

A sample configuration file, pyfehmrc_example, is included with the PyFEHM download. Copy this file to the site-packages folder in your Python installation, rename it to ‘pyfehmrc’ or ‘.pyfehmrc’, and modify according to the instructions inside.

Using this manual

This manual comprises sections for each of the important PyFEHM modules: fgrid, fdata, fpost, and fvars. In these, the important classes and their methods are documented, and example usage provided.

One way to get acquainted with PyFEHM is to work through the tutorials provided. These provide an introduction to the basic workflow of creating, running and visualising an FEHM simulation. They also document some of the more specialised capabilities of PyFEHM.

Table Of Contents

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Welcome to PyFEHM’s documentation!

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fgrid: FEHM grid manipulation

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