Two flow patterns are represented by their stream functions ψ1 and ψ2 as given below: ψ1 = x2 + y2, ψ2 = 2xy If these two patterns are superimposed on one another, the resulting streamline pattern can be represented by one of the following :

• A family of parallel straight lines
• A family of circles
• A family of parabolas
• A family of hyperbolas