Upper-convected Maxwell model (source code)

= Upper-convected Maxwell model
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The <Upper-convected Maxwell model> evolves viscoelastic <stress> according to
$$
\boldsymbol\tau+\lambda\overset{\triangledown}{\boldsymbol\tau}
=\eta\dot{\boldsymbol\gamma}.
$$
It has constant shear <viscosity> and predicts a divergent <extensional viscosity> at a finite extension rate.