No, it is not possible to pass the species model as an argument to C_UDSI(c, t, i) in ANSYS Fluent. C_UDSI is a user-defined scalar function that allows you to access and modify user-defined scalar variables associated with a cell (c), thread (t), and index (i).

Within the DEFINE_SOURCE macro, you can access the species concentrations using the FLUENT macros C_YI(c, t, i), which returns the mass fraction of species i in cell c and thread t.

Thank you.