Sudden Area Change (TL) Reynolds Number Basis

Hello,

I am simulating pressure drop through an expansion in a thermal liquid system. I have chosen to do this by using the Sudden Area Change (TL) block ( https://www.mathworks.com/help/physmod/hydro/ref/suddenareachangetl.html ) from the Simscape Fluids add on. Since I have CFD data and soon test data for this particular expansion, I am trying to use the feature of specifying the loss coefficient as a function of Reynolds number via table entry.

The problem is that the Reynolds number definition is explicitly specified for which dimension should be used. The closest I see to a definition is the description of the critical number in the transition zone which indicates it should be based on the smaller (contraction area).

Can anyone confirm this to be true? It seems like the definition may depend on the flow direction because even if I input the same loss coefficient for the contraction or expansion, reversing the block's orientation in the model will influence the result when I would expect it to be the same.

Is it possible to get more information on how this block functions?

Thank you.