- Partial Differential Equations:
- Boundary Conditions:
with
*U*(*x*) the known potential flow velocity just above the boundary layer. - Initial condition:
*u*(-*x*,0) = 0_{0}*x*=-*x*the known location of the stagnation point._{0}

Advantages of a vorticity formulation:

- The pressure gradient does not need to be extracted from
*U*(*x*). No consistency problems either. - Boundary conditions on the vorticity can be applied directly.
- Almost unavoidable in 2nd-order boundary-layer theory.