如何增加两个并排图形的标题之间的距离？

Question

现在我用的是这个：

\begin{figure}
    \centerline{
        \begin{subfigure}{0.6\textwidth}
        \includegraphics[scale=0.5]{images/mesh12}
        \caption{The acoustic pressure field of a finely meshed 2D model according to equation~\ref{eq:numberofelements} (12 mesh elements per wavelength).}
        \label{fig:mesh1}
        \end{subfigure}
        \begin{subfigure}{0.6\textwidth}
            \includegraphics[scale=0.5]{images/mesh4}
            \caption{The acoustic pressure field of a 2D model with 4 mesh elements per wavelength. }
            \label{fig:mesh2}
        \end{subfigure}
    }
    \caption{Two 2D simulations of the acoustic pressure field with different mesh resolutions. The slit in the middle of the circle is the smartphone and the outer ring is the PML. A single speaker is used. The axes are in meters.}
    \label{fig:mesh4and12}
\end{figure}

得到如下图片：

我的问题在于图 (a) 和 (b) 的子标题彼此太近，看起来像长句子。如何在这两个标题之间添加空格？

谢谢！

Answer 1

减小环境尺寸subfigure，例如0.47\textwidth，将图形放置在\hfill与图像尺寸之间，并用以下方法确定with=\linewidth：

\documentclass{article}
\usepackage[demo]{graphicx}
\usepackage{subcaption}
\usepackage[font={it,footnotesize}]{caption}

\begin{document}
\begin{figure}
    \centerline{
        \begin{subfigure}[t]{0.47\textwidth}
        \includegraphics[width=\linewidth]{images/mesh12}
        \caption{The acoustic pressure field of a finely meshed 2D model according to equation~\ref{eq:numberofelements} (12 mesh elements per wavelength).}
        \label{fig:mesh1}
        \end{subfigure}
        \hfill
        \begin{subfigure}[t]{0.47\textwidth}
            \includegraphics[width=\linewidth]{images/mesh4}
            \caption{The acoustic pressure field of a 2D model with 4 mesh elements per wavelength. }
            \label{fig:mesh2}
        \end{subfigure}
    }
    \caption{Two 2D simulations of the acoustic pressure field with different mesh resolutions. The slit in the middle of the circle is the smartphone and the outer ring is the PML. A single speaker is used. The axes are in meters.}
    \label{fig:mesh4and12}
\end{figure}
\end{document}

Answer 2

使用该floatrow包，您可以选择包含（子）图形及其（子）标题的框的宽度。下面是一个例子，我选择了图形对象的自然宽度：

\documentclass{article}
\usepackage{caption, subcaption}
\usepackage{floatrow}
\usepackage[demo]{graphicx}
\usepackage[showframe]{geometry}
\DeclareFloatSeparators{qqquad}{\hspace{3em}}

\begin{document}

\begin{figure}
\floatsetup{subfloatrowsep =qqquad}
    \ffigbox[\FBwidth]{\begin{subfloatrow}
    \ffigbox[\FBwidth]{\includegraphics[width=0.4\textwidth]{images/mesh12}}
    {\caption{The acoustic pressure field of a finely meshed 2D model according to equation~\ref{eq:numberofelements} (12 mesh elements per wavelength).}
    \label{fig:mesh1}}
       \ffigbox[\FBwidth]{ \includegraphics[width=0.4\textwidth]{images/mesh4}}
        {\caption{The acoustic pressure field of a 2D model with 4 mesh elements per wavelength. }
        \label{fig:mesh2}}
    \end{subfloatrow}} {\caption{Two 2D simulations of the acoustic pressure field with different mesh resolutions. The slit in the middle of the circle is the smartphone and the outer ring is the PML. A single speaker is used. The axes are in meters.}
\label{fig:mesh4and12}}
\end{figure}

\end{document}