2

I'm using the amsmath package, in the subequations environment I have the following set of equations

\begin{subequations}
\begin{align}
&\rho\left(u\frac{\partial u}{\partial x}+v\frac{\partial u}{\partial r}\right)=-\frac{\partial P}{\partial x}+\frac{M^2_\infty}{Re}\frac{1}{r}\frac{\partial}{\partial r}\left(\mu r\frac{\partial u}{\partial r}\right)\\
&\rho\left(u\frac{\partial h}{\partial x}+v\frac{\partial h}{\partial r}\right)=\rho\left(u\frac{\partial P}{\partial x}+v\frac{\partial P}{\partial r}\right)+\frac{M^2_\infty}{Re\dot Pr}\frac{1}{r}\frac{\partial}{\partial r}\left(\mu r\frac{\partial h}{\partial r}\right)+\frac{M^2_\infty}{Re}\mu\left(\frac{\partial u}{\partial r}\right)^2
\end{align}
\end{subequations}

Using this code, the reference for the second equation is pushed to the line below. What I'm trying to figure out is how to send

+\frac{M^2_\infty}{Re}\mu\left(\frac{\partial u}{\partial r}\right)^2

onto another line, aline it with the equals signs without it gaining it's own equation reference.

Any ideas?

5

Use the split environment, it works like align

\begin{subequations}
\begin{align}
  \rho\left(u\frac{\partial u}{\partial x}+v\frac{\partial u}{\partial r}\right)
  &= -\frac{\partial P}{\partial x} +
  \frac{M^2_\infty}{Re}\frac{1}{r}\frac{\partial}{\partial r}\left(\mu
    r\frac{\partial u}{\partial r}\right)\\ 
  \begin{split}
    \rho\left(u\frac{\partial h}{\partial x} + v \frac{\partial h}{\partial r}
    \right) &= \rho \left( u\frac{\partial P}{\partial x} + v
      \frac{\partial P}{\partial r} \right) \\
    &\quad{}+\frac{M^2_\infty}{Re\dot Pr} \frac{1}{r}\frac{\partial}{\partial r}
    \left(\mu r\frac{\partial h}{\partial r} \right) + \frac{M^2_\infty}{Re} \mu
    \left( \frac{\partial u}{\partial r}\right)^2
  \end{split}
\end{align}
\end{subequations}

enter image description here

  • 1
    i'd suggest the following minor changes: in the second (split) subequation, make the line break after the first, rather than the second, parenthesized expression on the right-hand side, and introduce a \quad{} after the & following the line break, so that the plus is set below the \rho instead of below the equal sign. (the {} will enforce the correct spacing after the plus.) – barbara beeton Jun 14 '13 at 15:04

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