Hi Gregory,
I can't think of an obvious way to approach this kind of setup that excludes all forms of scripting. You could try it just by manipulating colliders and local forces, so as the floating particle approaches the particles on the bed they get pulled off by it and the nature of the repulsive forces between the particles spreads them out around the floating particle...but then getting them to re-join the next bed of particles and doing it all in such a controlled manner will be very difficult without the precise control that scripting offers.
I can't think of an obvious way to approach this kind of setup that excludes all forms of scripting. You could try it just by manipulating colliders and local forces, so as the floating particle approaches the particles on the bed they get pulled off by it and the nature of the repulsive forces between the particles spreads them out around the floating particle...but then getting them to re-join the next bed of particles and doing it all in such a controlled manner will be very difficult without the precise control that scripting offers.