root/trunk/matml/transport/problems/coextrude/coextrude.tex

\documentclass{article}
\usepackage{fullpage}
\newcommand{\PSbox}[3]{\mbox{\rule{0in}{#3}\special{psfile=#1}\hspace{#2}}}
\begin{document}
\begin{enumerate}
\item Coextrusion of multilayer polymer sheets

  The ``multilayer coextrusion'' process shown below produces a sheet comprised
  of alternating layers of different polymers.
  \begin{center}
    \PSbox{coextrude-fig.ps}{277pt}{206pt}
  \end{center}

  \begin{enumerate}
  \item Sketch the fully-developed velocity profile of the liquid polymers in
    the die (treat them as a single pseudoplastic fluid).

  \item Sketch the velocity profile of the solid sheet that has exited the die.

  \item The layers are uniform while flowing through the block and die.
    However, after exiting the die, the layers are not uniform.  Sketch the
    layer thicknesses you would expect to see in a sheet cross-section.  (Hint:
    the ``flow rate'' in each layer is the same in the die and sheet.)
  \end{enumerate}
\end{enumerate}
\end{document}