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What's the source for your quote? I don't really follow the:
The best way to get the velocity variation is to use the "Newton" theory and determine the flow turning caused by a given shape.
The velocity field is found by solving the partial differential equation that governs it (Laplace's equation for the velocity potential). I don't see how the "Newton theory" as it has been presented here (macroscopic application of Newton'd second law) helps with that, except in the sense that all fluid mechanics, including Bernoulli's theorem, is ultimately an application of Newton's laws at the microsopic level.