A blade includes an airfoil body defined by a concave pressure side outer wall and a convex suction side outer wall that connect along leading and trailing edges and, therebetween, form a radially extending chamber for receiving the flow of a coolant. The airfoil body has an inner surface facing the radially extending chamber and an outer surface, a first corrugated surface on a portion of the outer surface, and a second corrugated surface on the inner surface paralleling the first corrugated surface. The corrugated surface on the outer surface of the airfoil provides wake mixing. The blade may also include an integrally formed impingement cooling structure having a third corrugated surface parallel to the second corrugated surface, which is made possible through additive manufacturing. The impingement cooling structure so formed provides improved cooling of the blade.