# Theory PagesΒΆ

In these pages we provide detailed theory for the various simulation capacities in PFLOTRAN-OGS.

- The Mathematical Formulation of GAS_WATER
- The Mathematical Formulation of TOIL_IMS
- The Mathematical Formulation of the Black Oil Model
- The Mathematical Formulation of the Solvent Todd-Longstaff Model
- The Mathematical Formulation of the Simple Todd-Longstaff Model
- Miscible Treatment
- Solving the Flow Equations
- Fluid component Properties
- Rock Compressibility Model
- The Characteristic Curves Smoother
- The Well Model
- Directional Relative Permeability
- Residual Trapping and Stranded Gas Saturation