If you import a reaction mechanism (in Chemkin format) or if you need specific species in your solution, which are not part of the default thermodynamic database (thermo.db), you typically use a specific thermodynamic database file in a fluent case with a PDF based combustion model. If you now move such a fluent case to a different drive / folder, fluent often fails to find the specified thermodynamic database file: “… Cannot find thermo database file … Reverting to default …” This can be solved by specifying the updated path to the thermodynamic database with: (rpsetvar ‘prepdf/default-thermo-db-fname “/path/custom_therm.dat”) This change (path to thermodynamic database) is saved in the fluent case file. Keywords: Fluent, species, reaction, Non-Premixed Combustion, PDF, thermo database file, thermo.db