Math & Science ⇒ Spacing between Equations

[Juggler123]

Hi all, first post here.

I'm writing up my master thesis and I'm finding inconsistent spacing between my equations. Below is an example:

Code: Select all

Equations (2.1) and (2.2) in component form are written as
%
\begin{equation} 
\frac{1}{r^{*}}\frac{\partial}{\partial r^{*}}(r^{*}u^{*})+\frac{1}{r^{*}}\frac{\partial v^{*}}{\partial\theta}+\frac{\partial w^{*}}{\partial z^{*}}=0,
\label{1}
\end{equation}
%
\begin{multline} 
\rho\left[u^{*}\frac{\partial u^{*}}{\partial r^{*}}+\frac{v^{*}}{r^{*}}\frac{\partial u^{*}}{\partial\theta}+w^{*}\frac{\partial u^{*}}{\partial z^{*}}-\frac{\left(v^{*}+r^{*}\Omega\right)^2}{r^{*}}\right]=-\frac{\partial p^{*}}{\partial r^{*}}+\frac{1} {r^{*}}\frac{\partial}{\partial r^{*}}\left(r^{*}\tau_{r^{*}r^{*}}^{*}\right)
\\
+\frac{1}{r^{*}}\frac{\partial}{\partial\theta}\tau_{r^{*}\theta}^{*}-\frac{\tau_{\theta\theta}^{*}}{r^{*}}+\frac{\partial}{\partial z^{*}}\tau_{r^{*}z^{*}}^{*},
\label{2}
\end{multline}
%
\begin{multline} 
\rho\left[u^{*}\frac{\partial v^{*}}{\partial r^{*}}+\frac{v^{*}}{r^{*}}\frac{\partial v^{*}}{\partial\theta}+w^{*}\frac{\partial v^{*}}{\partial z^{*}}+\frac{u^{*}v^{*}}{r^{*}}+2u^{*}\Omega\right]=-\frac{1}{r^{*}}\frac{\partial p^{*}}{\partial\theta}+\frac{1}{r^{*^{2}}}\frac{\partial}{\partial r^{*}}\left(r^{*^{2}}\tau_{\theta r^{*}}^{*}\right)
\\
+\frac{1}{r^{*}}\frac{\partial}{\partial\theta}\tau_{\theta\theta}^{*}+\frac{\partial}{\partial 				z^{*}}\tau_{\theta z^{*}}^{*},
\label{3}
\end{multline}
%
\begin{equation} 
\rho\left[u^{*}\frac{\partial w^{*}}{\partial r^{*}}+\frac{v^{*}}{r^{*}}\frac{\partial w^{*}}{\partial\theta}+w^{*}\frac{\partial w^{*}}{\partial z^{*}}\right]=-\frac{\partial p^{*}}{\partial z^{*}}+\frac{1}{r^{*}}\frac{\partial}{\partial r^{*}}\left(r^{*}\tau_{z^{*}r^{*}}^{*}\right)+\frac{1}{r^{*}}\frac{\partial}{\partial \theta}\tau_{z^{*}\theta}^{*}+\frac{\partial}{\partial z^{*}} \tau_{z^{*}z^{*}}^{*}.
\label{4}
\end{equation}

Can anyone help? Why are the equations so poorly spaced here? Is it because I am using equation then multline? I'm am required to us 12pt font and double spaced lines.
Any help would be great, thanks.

[cgnieder]

If I open your example in writelatex (with the button above from the code box) the only thing I can see is that the fourth equation apparently is too long for the textwidth (at least with standard settings, fonts, ...)

My guess is that you have this as a series of equations following each other with no text in between? If that is right you probably want one of amsmath's multi-line equation environments, e.g., gather:

Code: Select all

\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}

\begin{gather} 
\frac{1}{r^{*}}\frac{\partial}{\partial r^{*}}(r^{*}u^{*})+\frac{1}{r^{*}}\frac{\partial v^{*}}{\partial\theta}+\frac{\partial w^{*}}{\partial z^{*}}=0,
\label{1}
 \\
 \begin{split}
\rho\left[u^{*}\frac{\partial u^{*}}{\partial r^{*}}+\frac{v^{*}}{r^{*}}\frac{\partial u^{*}}{\partial\theta}+w^{*}\frac{\partial u^{*}}{\partial z^{*}}-\frac{\left(v^{*}+r^{*}\Omega\right)^2}{r^{*}}\right]=-\frac{\partial p^{*}}{\partial r^{*}}+\frac{1} {r^{*}}\frac{\partial}{\partial r^{*}}\left(r^{*}\tau_{r^{*}r^{*}}^{*}\right)
\\
+\frac{1}{r^{*}}\frac{\partial}{\partial\theta}\tau_{r^{*}\theta}^{*}-\frac{\tau_{\theta\theta}^{*}}{r^{*}}+\frac{\partial}{\partial z^{*}}\tau_{r^{*}z^{*}}^{*},
\label{2}
 \end{split}
 \\
 \begin{split} 
\rho\left[u^{*}\frac{\partial v^{*}}{\partial r^{*}}+\frac{v^{*}}{r^{*}}\frac{\partial v^{*}}{\partial\theta}+w^{*}\frac{\partial v^{*}}{\partial z^{*}}+\frac{u^{*}v^{*}}{r^{*}}+2u^{*}\Omega\right]=-\frac{1}{r^{*}}\frac{\partial p^{*}}{\partial\theta}+\frac{1}{r^{*^{2}}}\frac{\partial}{\partial r^{*}}\left(r^{*^{2}}\tau_{\theta r^{*}}^{*}\right)
\\
+\frac{1}{r^{*}}\frac{\partial}{\partial\theta}\tau_{\theta\theta}^{*}+\frac{\partial}{\partial                                 z^{*}}\tau_{\theta z^{*}}^{*},
\label{3}
 \end{split}
 \\
\rho\left[u^{*}\frac{\partial w^{*}}{\partial r^{*}}+\frac{v^{*}}{r^{*}}\frac{\partial w^{*}}{\partial\theta}+w^{*}\frac{\partial w^{*}}{\partial z^{*}}\right]=-\frac{\partial p^{*}}{\partial z^{*}}+\frac{1}{r^{*}}\frac{\partial}{\partial r^{*}}\left(r^{*}\tau_{z^{*}r^{*}}^{*}\right)+\frac{1}{r^{*}}\frac{\partial}{\partial \theta}\tau_{z^{*}\theta}^{*}+\frac{\partial}{\partial z^{*}} \tau_{z^{*}z^{*}}^{*}.
\label{4}
\end{gather}
\end{document}

You can read more on such environments in mathmode.

Regards