recurrence tutorial: laminar vortex shedding

This 2D case of vortex shedding in laminar cross-flow demonstrates the
concept of recurrence.

This is a bit work-in-progress: please check whether this tutorial runs with
the recurrence model and tools of CFDEMcoupling, namely rStatAnalysis.

The simulation roughly goes through three stages:
  * The initial solution computed by potentialFoam
  * A period of symmetric, steady-state flow
  * Finally, periodic vortex shedding

These three stages are clearly visible in the recurrence plot.

  * We see how not one of the later velocity fields is similar to the initial one
  * We see the intermediate stage with a symmetric flow field
  * We see the periodic vortex shedding

tutorials/rStatAnalysis/laminarFlowOvercylinder/recMat/plotDistMat.gnu

@@ -0,0 +1,48 @@
+reset
+clear
+
+set terminal cairolatex pdf dash dl 1
+
+set pm3d map
+set contour surface
+set cntrparam levels discr 10 
+set samples 50
+set isosamples 50 
+
+set palette maxcolors 8
+set palette defined(\
+0 0.2314 0.2980 0.7529,\
+0.125000 0.384300 0.509800 0.917600,\
+0.250000 0.552900 0.690200 0.996100,\
+0.375000 0.721600 0.815700 0.976500,\
+0.500000 0.866700 0.866700 0.866700,\
+0.625000 0.960800 0.768600 0.678400,\
+0.750000 0.956900 0.603900 0.482400,\
+0.875000 0.870600 0.376500 0.302000,\
+1 0.7059 0.0157 0.1490\
+)
+
+set cbtics 0.6
+set mcbtics 8
+#set cblabel 'distance'
+#unset cbtics
+set cbrange [0:0.6]
+set format cb "%.1f"
+
+#set xrange[0:3]
+#set yrange[0:3]
+
+set xlabel 't [s]'
+set ylabel 't [s]'
+
+# evil manual meddling with axes tics
+set xtics ("0" 0, "500" 50, "1000" 100, "1500" 150, "2000" 199)
+set ytics ("0" 0, "500" 50, "1000" 100, "1500" 150, "2000" 199)
+#set mxtics 2
+#set mytics 2
+
+set size square
+
+
+set out 'myDistMatrix.tex'
+splot 'myMatrix.txt' matrix using ($1):($2):(1-$3) with image notitle