Rotation properties in a sea of particles, will produce spiral structures, similarly to how an O-ring, in a sea of particles, will start to produce patterns.
Sphere-like particles within a pressurised environment, can rotate synchronous with each other when they rotate in opposite directions, or in the same direction, when they are behind each other and closely aligned. They need to be in even numbers to keep the flow going. The most basic formation they can form is in a square, made up of 4 particles. If you have one particle that is the driving force (8) than two squared formations can be formed, one on the right and one on the left side. This setting leaves a gap at the bottom and top, where there is are particles that can not fit in, because in-between spacing is to large, and when it wants to join in, a triplet is formed causing friction so the particles (red) bounce loosely in-between without having the chance to attach itself. This is a Basic law out of which vertex spirals are born, because new particle-formations can attach themselves on, or slipstream behind, the exterior particles of the formation (green) while the red ones keeps pushing the stream outwards.