Section: Fluid Mechanics | Marks: 2
In a steady two-dimensional incompressible flow, the stream function ($\psi$) obeys the equation $\frac{\partial^2 \psi}{\partial x^2} + \frac{\partial^2 \psi}{\partial y^2} = 4$. A solution of this equation is
- A. $\psi = x^2 + y^2$
- B. $\psi = y^2 - x^2$
- C. $\psi = xy$
- D. $\psi = x + y$