

All integrable Hamiltonian systems are alike, while each nonintegrable one is nonintegrable in its own way
vortex shedding (POV-Ray)
Vortex shedding around a half-cylinder rendered by POV-Ray (pdf, high resolution png).
Here the POV-Ray arrow layer is produced from Gerris (gfs) output with the command
vfplot -v -w4i -m2/2/0.2 -s0.0002 -i250/4 -l0/1in \
-d bvk.dom --cache 1024 -e0.1p --glyph triangle \
--output-format povray -o vfplot.inc \
--format gfs frame-2.0.gfs
producing vfplot.inc.
As in the PostScript version of this image, the vorticity is extracted from the gfs file to make a GMT grd file vort.grd but now this is used to make a png of the vorticity:
grdimage vort.grd -R-0.3/0.7/-0.3/0.3 -JX4i/2.4i \
-Cpolar > vort.eps
convert -density 300 -trim vort.eps -rotate 90 vort.png
in the file vort.png. Then the following POV-Ray script uses this to colour the cone glyphs in the image.
#include "colors.inc"
#include "shapes.inc"
#declare CD = 130;
#declare MX = 144;
#declare MY = 86;
camera {
location <1.3*MX, MY, -CD>
look_at <MX, MY, 0>
}
light_source {
<0, 0, -CD>
color rgb 0.5
parallel
point_at <0, 0, 0>
}
light_source { < 0, MY, -CD> color rgb 0.3 }
light_source { <2*MX, MY, -CD> color rgb 0.3 }
light_source { < MX, 2*MY, -CD> color rgb 0.4 }
background { color rgb 0.9 }
#declare vfplot_arrow_texture =
texture {
pigment {
image_map {png "vort.png" once}
scale <288, 173, 1>
}
finish {
phong 0.5
}
};
#include "vfplot.inc"
object {
intersection {
Round_Cone_Merge(<85, 85, -10>, 35, <85, 85, 10>, 35, 1)
plane { x, 85 }
}
pigment { color rgb 0.8 transmit 0.45 }
finish {
phong 0.5
}
}
Details on vfplot POV-Ray output can be found here.
