Axisymmetric Reference Area
 

Using a reference area of 0.5 m for a 1m diameter sphere, as suggested elsewhere on this forum, works fine. Fluent relates the 2D r=0.5 m reference area to the 3D [ pi*r^2 ] projected area. (I hope my understanding is correct here?)

Now I have an axisymmetric body, in water. In marine applications it is commen not to use the projected area but the wetted surface. Now I wonder: In this case, what would be the correct 2D reference area?