The scaling of cluster velocity at the wall of circulating fluidized bed risers

When the cluster velocity is seemingly unstirred by the over flow conditions, it is likely that is set by local force balance at the wall. Its apparent insensitivity to the properties and velocity of the gas further proposes that interactions in the particle phase dominate the balance. In this case the only parameters significant to the velocity scaling would include the material density and mean diameter of the particles, the gravitational acceleration and if the particles are engaged in collisional interactions, the parameters characterizing the impacts.