  d'Alembert's paradox is the contradictory observation that for incompressible
and inviscid (potential) fluid flow, there is no drag force experienced by a
body moving with constant velocity relative to the fluid. This paradox can be
straightforwardly resolved by considering Navier's slip boundary condition.
Potential flow around a cylinder then solves the Navier--Stokes equations using
friction parameter $\beta=-2\nu$. This negative friction parameter can be
interpreted physically as the fluid being accelerated by the cylinder wall.
This explains the lack of drag.
  In this paper, we introduce the Navier slip boundary condition and show that
choosing the friction parameter positive resolves d'Alembert's paradox. We then
further examine the effect of the friction parameter $\beta$ on the drag
coefficient. In particular, we show that for large $\beta$ the drag coefficient
corresponds well with experimental values. Moreover, we provide numerical
evidence that the Newton continuation method (moving from small to large
Reynold's numbers) requires fewer iterations to succeed. Thus the slip boundary
condition is advantageous also from a computational perspective.
