https://doi.org/10.7291/D1VQ3R

FEHM archive for Fisher et al. (2024), "Sustaining hydrothermal circulation with gravity relevant to ocean worlds," revised following review for Journal of Geophysical Research - Planets.

NB: Above will be revised when paper is in print, and a DOI will be added.

Description of the data and file structure

Three compressed (zip) files are included in this archive:

10_FEHM-Linux_Diffg_Exe.zip
20_FEHM-SourceEdited.zip
30_FEHM-InputDirs.zip

Code/Software

10_FEHM-Linux_Diffg_Exe.zip

Contains executable FEHM programs with gravity for Earth, Europa, and Enceladus:
xfehm_v3.4g9_81 gravity for Earth, 9.81 m/s^2
xfehm_v3.4g1_3 gravity for Europa, 1.3 m/s^2
xfehm_v3.4g_114 gravity for Enceladus, 0.114 m/s^2

These codes were compiled with Rocky Linux using the gfortran compiler (part of gcc family of compilers).

Posted executables may work for your system, or you may need/wish to recompile in order to access libraries.

We have also supplied shell scripts we used to call the executables, based on having a set of input files with common root names and different file extensions. The "Files" file tells FEHM which files to use for input and output. You may need to modify these scripts depending on your workflow, how you name your files, etc. Please see file examples in 30_FEHM-InputDirs.zip, and follow the guidance given at the FEHM site at LANL (https://fehm.lanl.gov/.

20_FEHM-SourceEdited.zip

Please follow these steps to use the modified subroutines:

(1) Start with the original source code in 20_FEHM-SourceEdited --> src subdirectory

Place the full directory set in a suitable workspace, e.g., ~/code/FEHM

[Note - we originally recommended that folks download source code from Github, but there have been changes made recently to some of the FEHM subroutines. For this reason, we have uploaded a "snapshot" of the sourcecode files for which we have confirmed compilation works.]

- Before doing anything else, we strongly encouarge recompiling the original code, as this will tell you if any changes are needed to your system settings, paths, gfortran/gcc installation, libraries, etc.

- You must edit the Makefile to be consistent with your computer system in order for the Make command to be successful in generating an executable program.

- If you are not able to compile from the src distribution, please solve that problem first, before proceeding. We have noted differences in systems and settings in terms of compilers be tolerant of deviations in standard Fortran syntax, so you should expect some minor debugging on first compilation.

(2) Create a working subdirectory for compilation of modified code, e.g., ~/code/FEHM/src_g9_81, and copy over the contents of the FEHM source directory, which has already been confirmed to allow successful recompilation.

(3) Copy to the working subdirectory the appropriate files from the directory in the zip file, e.g., src_g9_81. In this directory you will find these files:

comai.f

convctr.f

hstz.f

inctrl.f

input.f

Makefile

plot_new.f

porosi.f

startup.f

write_avs_node_s.f

wrtout.f

In brief - these files REPLACE the files with the same names included in the original FEHM distribution.

(4) Edit the Makefile to name the executable as you wish, on line that begins:

EXE = ...

Note - you might need to make additional updates to the revised Makefile if you had to modify the original Makefile when you recompiled without the modified subroutines.

(5) If you wish to use g = 9.81 m/s^2, no other changes are needed before compilation. If you wish, you can redefine gravity for another ocean world. There are two lines that need to be changed in inctrl.f - search for 9.81 (or AF***) to find them, adjust as needed. All other files in FEHM will use values as defined in inctrl.f

(6) At the command prompt in the working directory, run these commands:

make clean

make

- The first command will clear any residual object files or remnants from any earlier attempts to compile the code. This is important so that the new object files are used to create the executable.

- The second command will create new objects and an executable.

(7) To run a quick test to see if the executable works, enter at command prompt in the working directory:

./FEHM-Filename

where "FEHM-Filename" is what you defined at the line that begins EXE = in the Makefile

You should see that FEHM runs, but there will be an error because input files have not been specified.

To set up a FEHM simulation, you will need to follow instructions provided at the FEHM website. LANL has documentation here: https://fehm.lanl.gov/

This includes links to source code on GitHub and gridding software.

30_FEHM-InputDirs.zip

Example directories are provided for running FEHM to duplicate results shown in Figure 3 of the main paper. This figure shows snapshots of results from four simulations, files for each of which are stored in separate subdirectories:
A_p12fto_OCv10_g981
B_p12d1200efto_OCv10_g1_3
C_p12d600efto_OCv10_g1_3r
D_p10d600efto_OCv10_g_114

A_p12fto_OCv10_g981

Shallow aquifer, aquifer permeabilty = 1e-12 m^2, Earth gravity

B_p12d1200efto_OCv10_g1_3

Deep-thick aquifer, aquifer permeabilty = 1e-12 m^2, Europa gravity

C_p12d600efto_OCv10_g1_3r

Deep-thin aquifer, aquifer permeabilty = 1e-12 m^2, Europa gravity

D_p10d600efto_OCv10_g_114

Deep-thin aquifer, aquifer permeabilty = 1e-10 m^2, Enceladus gravity

In addition to the input files in each directory, the user will need to copy over or add a static link for the fluid properties lookup table, nist120-1800.out, and update the name in the .files file to point to this table. The lookup table is provided in the parent folder for the four example folders listed above.

Please see the FEHM User Manual for more detailed instructions for use of FEHM, available with the GitHub repository: https://github.com/lanl/FEHM

Code modifications included in this repository are covered by the FEHM license, as described in the associated README file.