Span-wise momentum transport¶

\[ \begin{align}\begin{aligned}\pder{\vel{3}}{t} = & \dmomadv{3}{1} \dmomadv{3}{2} \dmomadv{3}{3}\\& \dmompre{3}\\& \dmomdif{1}{3} \dmomdif{2}{3} \dmomdif{3}{3}\end{aligned}\end{align} \]