Transport Efficiency and the Bruggeman Correlation

[ch662]

Hello, can someone please explain to me how transport efficiency is explicitly defined in Pybamm?
I saw how tortuosity was renamed to transport efficiency because it is defined differently in Pybamm, but I have had a hard time finding the exact differences.

For example, what is the difference between transport efficiency in Pybamm and the Bruggeman correlation as defined here:

[valentinsulzer]

Transport efficiency is defined as porosity to the power or Bruggeman coefficient (usually 1.5)