Unreal physics is not made for accurate simulation (well it kind of is, but also it is not).
Goal of unreal physics (and any games) is to make physics that LOOKS real (not behaves accurate).
So you can use unreal fluids physics to make believable stream around wing.
However do not use results from it to create gameplay mechanics, it will have weird quirks errors and be generally unstable.
For some wing simulation you should use real formulas then use unreal physics for looking acceptable visual feedback.