Region 2 Discussion
In this region, both types of drag have an effect (pressure and viscous drag). The velocity of the flowing object is higher than in the previous region, high enough that the adverse pressure gradients from point A to point D are more significant than region 1. This creates what is know as bound vortices behind the object. The bound vortices creates more pressure at D, which causes the fluid flowing in this direction to be flowing opposite to the pressure gradient. Not significant enough to produce a large wake region, but enough to cause separation bubbles to form.
The equation representing this region can be found below: