Rotate an arrow around its center

Question

I want to draw this with tikz,

I have been trying to do it with tikz for awhile but didnt get far, with suggestion I moved to PsTricks. This is what I have so far

\documentclass[pstricks,border=15pt]{standalone}
\usepackage{pstricks-add}
\definecolor{DarkOceanSky}{RGB}{133,163,229}
\definecolor{DarkNavyBlue}{RGB}{0,25,63}
\definecolor{Reu}{RGB}{102,173,76}
\definecolor{Crimson}{RGB}{220, 20, 60}
%second part
\def\block{%
        \foreach \x in {1,3,5,...,7}
        {
            \foreach \y in {1,3,5,...,7}
             {%
                \foreach \angle in {0,45,...,315}
                 {
                    \psrline{->}(\x,\y)(!0.10 Rand 1.4 mul add sqrt \angle\space PtoC)
                 }
             }
        }
    \foreach \counter in {0,2,4,6,...,8}
    {
        \psline{-, linecolor=DarkNavyBlue,linewidth=1.8pt}(\counter,0)(\counter,8)
        \psline{-, linecolor=DarkNavyBlue,linewidth=1.8pt}(0,\counter)(8,\counter)            
    }

    \pscircle*[linecolor=Crimson](4,4){0.2}

}
\begin{document}
\begin{pspicture}showgrid
        %\rput(12,0){\block}
        \rput(11.0,0){\block}
    \foreach \counter in {0,2,4,6,...,8}
    {
        \psline{-, linecolor=DarkNavyBlue,linewidth=1.8pt}(\counter,0)(\counter,8)
        \psline{-, linecolor=DarkNavyBlue,linewidth=1.8pt}(0,\counter)(8,\counter)            
    }

    \foreach \counter in {1,3,5,...,7}
    {
        \psline{-, linecolor=DarkNavyBlue,linewidth=1.0pt}(\counter,0)(\counter,8)
        \psline{-, linecolor=DarkNavyBlue,linewidth=1.0pt}(0, \counter)(8,\counter)
    }

    \foreach \counter in {0.5,1.5,2.5,3.5,4.5,5.5,6.5,...,7.5}
    {
        \psline{-, linecolor=DarkNavyBlue,linewidth=1.0pt}(\counter,0)(\counter,8)
        \psline{-, linecolor=DarkNavyBlue,linewidth=1.0pt}(0, \counter)(8, \counter)
    }


    \pscircle[linecolor=Reu](4,4){4.5}
    \pscircle*[linecolor=Crimson](4,4){0.2}


    %I need to draw those small arrows
    \psrline{->}(1.6, 0.1)(!0.10 Rand 0.3 mul add sqrt 45 PtoC)    

\end{pspicture}

\end{document}

What I need to do now is to create those small arrows on the left figure. They are tiny arrows. I am willing to settle for same size arrows. So basically, fixed-size arrows with different orientations. I think the way to do it is to draw an arrow horizontally and rotate it around the center with random degree. I dont know how to do this and not sure if it is the right way. Can you help me?

Answer 1

The placement of the tiny arrows should be optimized (as it is better to be dependent on the grid size and not TikZ’ coordinate system) but here is a two-nested-loops-randomized approach.

Code

\documentclass[tikz,convert=false]{standalone}
\usetikzlibrary{arrows} 
\definecolor{DarkOceanSky}{RGB}{133,163,229}
\definecolor{DarkNavyBlue}{RGB}{0,25,63}
\definecolor{Reu}{RGB}{102,173,76}
\definecolor{Crimson}{RGB}{220, 20, 60}
\begin{document}
\begin{tikzpicture}[
  declare function={
    minorGridStep=.125cm;
    majorGridStep=.5cm;
  },
  major grid/.style={
    line width=+.018cm,
    draw=DarkNavyBlue,
    step=majorGridStep,
  },
  minor grid/.style={
    line width=+.008cm,
    draw=DarkNavyBlue,
    step=minorGridStep
  },
  green circle/.style={
    draw=Reu,
    radius=1.1,
    line width=+.008cm
  },
  red dot/.style={
    fill=Crimson,
    radius=.05
  }
]
  \begin{scope}
     \path[minor grid] (-1,-1) grid (1,1);
     \path[major grid] (-1,-1) grid (1,1);

     \path[green circle] circle [];
     \path[red dot] circle [];

     \foreach \cRight in {0,...,15}
       \foreach \cDown[
         evaluate={\length=max(rnd*.9*minorGridStep,1.5\pgflinewidth)},
         evaluate={\angle=rnd*360}
       ] in {0,...,15}
         \draw[triangle 90 cap reversed-triangle 90 cap] ([shift=(\angle:-\length/2 pt)] \cRight/16*2-1+.0625,\cDown/16*2-1+.0625) -- ++ (\angle:\length pt);
  \end{scope}
\end{tikzpicture} 
\end{document}

Output

Answer 2

\documentclass[pstricks,border=15pt]{standalone}
\usepackage{pstricks-add}

\definecolor{DarkOceanSky}{RGB}{133,163,229}
\definecolor{DarkNavyBlue}{RGB}{0,25,63}
\definecolor{Reu}{RGB}{102,173,76}
\definecolor{Crimson}{RGB}{220,20,60}

\pstVerb{realtime srand}

\def\Grid{%
    \foreach \counter in {0,2,...,8}{%
        \psset{linecolor=DarkNavyBlue,linewidth=2\pslinewidth,linecap=2}
        \psline(\counter,0)(\counter,8)
        \psline(0,\counter)(8,\counter)          
  }%
}

\def\SubGrid{%
    \foreach \counter in {0,.5,...,8}{%
        \psset{linecolor=DarkOceanSky,linewidth=.5\pslinewidth,linecap=2}
        \psline(\counter,0)(\counter,8)
        \psline(0,\counter)(8,\counter)          
  }%
}

\def\Left{%
    \SubGrid
    \Grid
    \foreach \x in {.25,.75,...,7.75}{%
        \foreach \y in {.25,.75,...,7.75}{%
            \rput{!rand 3601 mod 10 div}(\x,\y){\psline{->}(-4pt,0)(4pt,0)}
        }%
    }%
    \pscircle[linecolor=Reu,linewidth=2\pslinewidth](4,4){4.5}
    \pscircle*[linecolor=Crimson](4,4){0.2}
}

\def\Right{%
    \Grid
    \foreach \x in {1,3,5,...,7}{%
        \foreach \y in {1,3,5,...,7}{%
            \foreach \angle in {0,45,...,315}{%
                \psrline{->}(\x,\y)(!0.10 Rand 1.4 mul add sqrt \angle\space PtoC)
            }%
        }%
    }%
    \pscircle*[linecolor=Crimson](4,4){0.2}
}

\begin{document}
\begin{pspicture}[showgrid=false](18,9)
    \rput(.5,.5){\Left}
    \rput(10,.5){\Right}
\end{pspicture}
\end{document}