Question: Let
f(z) = (m - ik)/(2Π) Log((z - a)/(z - b))
in which m and k are nonzero real numbers and a and b are distinct complex numbers. Show that this flow has a source or sink of strength m and a vortex of strength k at both a and b. (A point combining properties of a source (or sink) and a vortex is called a spiral vortex). Sketch some equipotential curves and streamlines for this flow.