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Question

Math 6720 • Applied Complex Variables and Asymptotic Methods

Fall 2022 • Question 5

Consider a source at \(z=-a\) and a sink at \(z=a\) of equal strength \(k\). **(a)** (12 points) Show that the associated complex potential is \[ \Omega(z)=k\log\left[\frac{z+a}{z-a}\right]. \] **(b)** (13 points) Show that the flow speed is \[ \frac{2ka}{\sqrt{a^4-2a^2r^2\cos(2\theta)+r^4}}, \] where \(z=re^{i\theta}\).

Raw LaTeX

Consider a source at \(z=-a\) and a sink at \(z=a\) of equal strength \(k\).
\begin{enumerate}
\item
(12 points) Show that the associated complex potential is
\[
\Omega(z)=k\log\left[\frac{z+a}{z-a}\right].
\]
\item
(13 points) Show that the flow speed is
\[
\frac{2ka}{\sqrt{a^4-2a^2r^2\cos(2\theta)+r^4}},
\]
where \(z=re^{i\theta}\).
\end{enumerate}
\end{enumerate}