A steady, two-dimensional, incompressible, irrotational flow field in the rθ-plane has a stream function ψ and a velocity potential function φ.
(a) Write down the Cauchy-Riemann equations, in polar (cylindrical) coordinates, satisfied by the potential functions ψ and φ. [02]
(b) Let ψ be given as ψ(r, θ) = Aθ, where A is an arbitrary constant.
(i) Use (a) to determine φ. [06]
(ii) Find the equations for streamlines and equipotential lines.