Nikhil Narale
Ansys Employee

Hi, the reference values are used only for post-processing. These have no effect on the solution. At the same time, to get the logical results during post-processing, these values must be correct. For example, in a heat transfer problem, the value of the reference temperature will dictate the value of the surface heat transfer coefficient (which is a derived quantity) during post-processing

For more details, have a look at this section of the Fluent User's guide: 36.12. Reference Values (ansys.com)

If you are not able to access the link, refer to this forum discussion: How to access Fluent Documentation