An interactive demo using HTML5 canvas

You'll need a modern browser like Safari, Chrome, Firefox, Opera, or Internet Explorer 9+.
Keys: (or click below)
a: anim on/of <,>: speed TAB: time dir
t,T: trace mode (0-6) [,]: trace length x: add markers X: free markers
w: binary vorticity g: (picked) partic referential {,},= change partic (,),= partic size
+: add vortex -: del vortex s: change w sign -: saturate w
l,L: tune all/vortices/markers/cur f: sky color F: bg field
NB: resize window + reload page to change the playfield size.     Pick to set current particle.