It is important to note that the units for some inputs in Ansys Fluent are different from the units used for the rest of the problem setup.
You must always define the following in SI units, regardless of the unit system you are using:
Boundary profiles (see Profiles)
Source terms (see Defining Mass, Momentum, Energy, and Other Sources)
Custom field functions (see Custom Field Functions)
Data in externally-created XY plot files (see Creating an XY Plot From Multiple Data Sources (Including Files))
User-defined functions (See the Fluent Customization Manual for details about user-defined functions.)
If you define a material property by specifying a temperature-dependent polynomial or piecewise-polynomial function, remember that temperature in the function is always in units of Kelvin or Rankine. If you are using Celsius or Kelvin as your temperature unit, then polynomial coefficient values must be entered in terms of Kelvin; if you are using Fahrenheit or Rankine as the temperature unit, values must be entered in terms of Rankine. See Defining Properties Using Temperature-Dependent Functions for information about temperature-dependent material properties.