This is extremely cool! Amazing work @flockaroo

The implementation very different from other fluid simulations I've seen, copying the comments from the source:

    // single pass CFD - with some self consistency fixes

    // ...the actual fluid simulation

    // this is some "computational flockarooid dynamics" ;)
    // the self-advection is done purely rotational on all scales. 
    // therefore i dont need any divergence-free velocity field. 
    // with stochastic sampling i get the proper "mean values" of rotations 
    // over time for higher order scales.
    //
    // try changing "RotNum" for different accuracies of rotation calculation
    // for even RotNum uncomment the line #define SUPPORT_EVEN_ROTNUM