Differences in flow velocities promote mixing. Some blenders include mechanisms designed to produce different flow velocities in the material during operation. For example, the gravity mass-flow cone-in-cone blender promotes a faster velocity in the center of the vessel than on the side. This flow blending velocity profile extends up from the cone-in-cone kitchenaid immersion blender hopper about one hopper diameter high, typically resulting in a short, squat, low-volume blender. Using a cylinder-in-cylinder retrofit inside the blender's vertical portion above the cone-in-cone hopper section extends the blending profile far up into the vertical section. This can maintain a 5-to-1 height-to-diameter velocity profile ratio. Thereby allowing larger blender volumes.

Differences in flow velocities alone are not enough to pro- mote effective mixing. For example, a ribbon blender lifts and transports only a small quantity of material during one revolution, and it tends to lift material more efficiently than it transports material from side to side. The blender's action produces differences in flow velocities, but it also causes poor blender operation: It blends well vertically but mixes slowly end to end. Some ribbon blender users have discovered that optimal blending is possible only when individual ingredients are layered in the blender, because layering, in effect, does some of the mixing job, thereby decreasing reliance on flow velocity differences.