Splitting a group of long equations in LaTeX

Question

I have 3 equations which are long. These equations should be subequations and should be split and aligned. They should be given labels as well. I am attaching the code below.

\begin{subequations} \label{e33}
\begin{align}
\begin{split}
      q^{*}& = \Bigg(\dfrac{\alpha^{*}W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)}\Bigg)\  \overline{C}_1\overline{C}_3 - \Bigg(G_1^{*} +\overline{C}_2(T_p^{*}+T_1^{*})\cos\theta+G_2^{*}\overline{C}_1+G_3^{*}\overline{C}_1\overline{C}_3+ \overline{C}_1\overline{C}_4(T_p^{*}+T_2^{*})\cos\theta\Bigg)\  (\dfrac{W_{(i-1)}-2W_i+W_{(i+1)}}{(\Delta X)^{2}}) \label{e33a} 

        %\frac{\partial T_1^{*}}{\partial X}& = -\Bigg(q^{*}+G_1^{*}\frac{\partial^{2}W}{\partial X^{2}}\Bigg)\  \overline{D}_1 - \Bigg(\overline{C}_3\dfrac{\alpha^{*}W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)} - \Big(G_2^{*}+G_3^{*} \overline{C}_3+\overline{C}_4(T_p^{*}+T_2^{*})\cos\theta \Big) \frac{\partial^{2}W}{\partial X^{2}}\Bigg)\  \overline{D}_2 \label{e33b} \\
        %\frac{\partial T_2^{*}}{\partial X}& = -\Bigg(\frac{1}{\overline{C}_1} \Big(q^{*}+\bigg(G_1^{*}+\overline{C}_2(T_p^{*}+T_1^{*})\cos\theta \bigg)\frac{\partial^{2}W}{\partial X^{2}} \Big) +G_2^{*}\frac{\partial^{2}W}{\partial X^{2}} \Bigg)\ \overline{D}_3 - \Bigg(\dfrac{\alpha^{*} W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)} - G_3^{*}\frac{\partial^{2}W}{\partial X^{2}} \Bigg)\ \overline{D}_4       \label{e33c}
%\end{split}
%\end{align}
%\end{subequations}

Please provide me suggestions for the same.

Answer 1

Here's a first attempt:

\begin{subequations}
\begin{equation}\label{e33a}
\begin{split}
  q^{*} = & \Bigg(\dfrac{\alpha^{*}W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)}\Bigg)\  \overline{C}_1\overline{C}_3
  - \left(\dfrac{W_{(i-1)}-2W_i+W_{(i+1)}}{(\Delta X)^{2}}\right) \times \\
  & \Bigg(G_1^{*} +\overline{C}_2(T_p^{*}+T_1^{*})\cos\theta+G_2^{*}\overline{C}_1+G_3^{*}\overline{C}_1\overline{C}_3
  + \overline{C}_1\overline{C}_4(T_p^{*}+T_2^{*})\cos\theta\Bigg)
\end{split}
\end{equation}
\begin{equation}\label{e33b}
\begin{split}
  \frac{\partial T_1^{*}}{\partial X} = & -\Bigg(q^{*}+G_1^{*}\frac{\partial^{2}W}{\partial X^{2}}\Bigg)\  \overline{D}_1
    - \overline{D}_2 \Bigg(\overline{C}_3\dfrac{\alpha^{*}W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)} \\
   & - \Big(G_2^{*}+G_3^{*} \overline{C}_3+\overline{C}_4(T_p^{*}+T_2^{*})\cos\theta \Big) \frac{\partial^{2}W}{\partial X^{2}}\Bigg)
\end{split}
\end{equation}
\begin{equation}\label{e33c}
\begin{split}
  \frac{\partial T_2^{*}}{\partial X} = & -\Bigg(\frac{1}{\overline{C}_1} \Big(q^{*}+\bigg(G_1^{*}
  + \overline{C}_2(T_p^{*}+T_1^{*})\cos\theta \bigg)\frac{\partial^{2}W}{\partial X^{2}} \Big)
    +G_2^{*}\frac{\partial^{2}W}{\partial X^{2}} \Bigg)\ \overline{D}_3 \\
  & - \Bigg(\dfrac{\alpha^{*} W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)}
  - G_3^{*}\frac{\partial^{2}W}{\partial X^{2}} \Bigg)\ \overline{D}_4
\end{split}
\end{equation}
\end{subequations}

I think it's still way too cluttered. I would probably put some text in between and put each equation in a multline rather than a split.

---

Update: OK, I think the following is much nicer:

\begin{subequations}
Introductory text.
\begin{align}
  q^{*} = & \Bigg(\dfrac{\alpha^{*}W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)}\Bigg)\  \overline{C}_1\overline{C}_3
    - \left(\dfrac{W_{(i-1)}-2W_i+W_{(i+1)}}{(\Delta X)^{2}}\right) \times \label{e33a}\\
  & \Bigg(G_1^{*} +\overline{C}_2(T_p^{*}+T_1^{*})\cos\theta+G_2^{*}\overline{C}_1+G_3^{*}\overline{C}_1\overline{C}_3
    + \overline{C}_1\overline{C}_4(T_p^{*}+T_2^{*})\cos\theta\Bigg) \nonumber \\
\intertext{First intermissive text.}
  \frac{\partial T_1^{*}}{\partial X} = & -\Bigg(q^{*}+G_1^{*}\frac{\partial^{2}W}{\partial X^{2}}\Bigg) \; \overline{D}_1 \label{e33b} \\
  & - \Bigg(\overline{C}_3\dfrac{\alpha^{*}W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)}
    - \Big(G_2^{*}+G_3^{*} \overline{C}_3+\overline{C}_4(T_p^{*}+T_2^{*})\cos\theta \Big)
    \frac{\partial^{2}W}{\partial X^{2}}\Bigg) \; \overline{D}_2 \nonumber
\intertext{Second segway.}
  \frac{\partial T_2^{*}}{\partial X} = & -\Bigg(\frac{1}{\overline{C}_1} \Big(q^{*}+\bigg(G_1^{*}
    + \overline{C}_2(T_p^{*}+T_1^{*})\cos\theta \bigg)\frac{\partial^{2}W}{\partial X^{2}} \Big)
    + G_2^{*}\frac{\partial^{2}W}{\partial X^{2}} \Bigg)\ \overline{D}_3 \label{e33c} \\
  & - \Bigg(\dfrac{\alpha^{*} W}{U\big(1+\alpha^{*}(\frac{W}{q_u^{*}})\big)}
    - G_3^{*}\frac{\partial^{2}W}{\partial X^{2}} \Bigg)\ \overline{D}_4 \nonumber
\end{align}
\end{subequations}