Granular jump

Figure 8. Photograph of a transition in a chute flow, termed a granular jump from a dilute, high-speed flow upstream to a dense, low-speed flow downstream. From Johnson [37].

Granular jump in low velocity pneumatic conveying of solid particles in a horizontal pipeline... 

On the analogy of hydraulic jump in open channel flow, the granular jump can occur in a horizontal pneumatic conveying, provided that for a given U the particle flow pattern belongs to the suspension flow accompanied with the settled layer and that the particles are introduced into the pipe with velocity hi er than the equilibrium particle velocity for U. Since the deceleration of particle is not observed in the upstream side of the jump, it is infared that the particle is discontinuously decelerated at the jump. 

An incorrect jump to the same BB is an issue that cannot be solved purely by software-based techniques. The main problem is that the granularity required for that is at instmction level, while jumps to different BB require BB granularity. In order to detect errors inside the same BB, software-based technique would have to duplicate every instmction, which would lead to huge performance losses. From the related software-based techniques, none could detect such kind of error. 

An e q)eriment is presented that shows a discontinuous change of flow pattern like hydraulic jumps in avity flow of granular materials. In the upstream of jump the flow pattern is heterogeneous suspension flow where the particles mainly travel near the pipe bottom and suddenly changes to suspension flow accompanied with the particle settled layer of definite hei t where the particle velocity is decreased. The position of jump can be adjusted by changing the gas velocity. The e)q eriment is carried out in a horizontal strai t pipe of 30 mm m diameter and 5 m in length. Poly styrene beads are used, the diameter and the material density being 1.65 mm and 1034 kg/ m, respectively. 

C.E. Brennen, K.Sieck and J. Paslaski, Hydraulic jumps in granular material flow. Powder 7ec/ no/ogy35, pp.31-37 (1983). 

---