The TOUGH family of codes is a suite of computer programs for the simulation of multiphase fluid and heat flows in porous and fractured media with applications to geothermal reservoir engineering, nuclear waste disposal in geologic formations, geologic carbon sequestration, gas hydrate research, vadose zone hydrology, environmental remediation, oil and gas reservoir engineering, and other mass transport and energy transfer problems in complex geologic settings. Many modifications and enhancements have been made to TOUGH, at LBNL and elsewhere, from the time it was first released in 1987 to the current  TOUGH2 Version 2.1 and the pending 2018 release of TOUGH3.  Various descendants of the TOUGH codes (such as iTOUGH2, T2VOC, TMVOC, TOUGHREACT, TOUGH+, TOUGH2-MP, TOUGH-FLAC, and many more) are currently in use worldwide in many research laboratories, private companies, and universities.

See TOUGH Software website for more information.