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Math 6720 • Applied Complex Variables and Asymptotic Methods

Summer 2022 • Question 5

  1. Discuss the flow pattern around a circular obstacle associated with the complex potential \[ \Omega (z)=u_0\left (z+\frac {a^2}{z}\right )+\frac {i\gamma }{2\pi }\log z. \]
  2. Show that \(r=a\) is a streamline.
  3. Determine the asymptotic velocity when \(z\to \infty \). Sketch the flow when \(\gamma =0\).
  4. Use the Blasius formula \[ F_x-iF_y=\frac {1}{2}i\rho \int _C \left (\frac {d\Omega }{dz}\right )^2\,dz \] to determine the lift on the obstacle when \(\gamma \neq 0\).

Raw LaTeX

\begin{enumerate}
\item
Discuss the flow pattern around a circular obstacle associated with the complex potential
\[
\Omega(z)=u_0\left(z+\frac{a^2}{z}\right)+\frac{i\gamma}{2\pi}\log z.
\]
\item
Show that \(r=a\) is a streamline.
\item
Determine the asymptotic velocity when \(z\to\infty\). Sketch the flow when \(\gamma=0\).
\item
Use the Blasius formula
\[
F_x-iF_y=\frac{1}{2}i\rho\int_C \left(\frac{d\Omega}{dz}\right)^2\,dz
\]
to determine the lift on the obstacle when \(\gamma\neq 0\).
\end{enumerate}