diff --git a/LDDsimulation/README.md b/LDDsimulation/README.md
index 9c165d3a05d58aa5a6ea24215005909a740bc7d9..468b3e144194874a21bbd29886439fdd003c9544 100644
--- a/LDDsimulation/README.md
+++ b/LDDsimulation/README.md
@@ -19,10 +19,23 @@ which gets called by the `main()` of each usecase (more precisely by
 ## `boundary_and_interface.py`
 
 ## `solutionFile.py`
+This file defines a class `SolutionFile(dolfin.XDMFFile)` around the `dolfin`
+`XDMFFile` class and sets some parameters for the files in which the solution
+gets saved.
 
 ## `domainSubstructuring.py`
+This file defines various subdomains and their subdomain substructurings to be
+used in the simulation. A lengthy explanation on how to define your own substructurings is given in the file itself.
+Most likely, you will learn how to to this by looking at the examples given in the file.
 
 ##  `functions.py`
+This file defines data functions like relative permeabilities and pc-S relationships along with methods `generate_relative_permeability_dicts` and
+`generate_Spc_dicts` to generate dictionaries of callables that get passed to
+the simulation class.
+This was done in an attempt to tidy the usecases and have a central place in which to define data functions.
+New relative permeabilites and pc-S relationships must be specified here and
+the corresponding generator functions
+`generate_relative_permeability_dicts` and `generate_Spc_dicts` need to be adjusted accordingly. 
 
 ## `helpers.py`